,transcriber's ,notes3 ,text enclosed by underscores is in italics 7italics71 and text enclosed by equal signs is in bold 7bold74 ,additional ,transcriber's ,notes are at the end4 99 99 99 99 99 ,,books ,,on ,,popular ,,science ,,by ,,charles ,r4 ,,gibson1 ,f4,r4,s4,e4 8,mr4 ,gibson has a fine gift of exposition40--,birmingham ,post4 8,mr4 ,gibson has fairly made his mark as a populariser of scientific knowledge40--,guardian4 ,,in ,,the ,,science ,,for ,,children ,,series4 ,illustrated4 #ds4 #f;d4 nett each4 ,,our ,,good ,,slave ,,electricity4 ,,the ,,great ,,ball ,,on ,,which ,,we ,,live4 ,,the ,,stars ,,their ,,mysteries4 ,,war ,,inventions ,,how ,,they ,,were ,,invented4 ,,chemistry ,,its ,,mysteries4 ,,in ,,the ,,science ,,of ,,to-,,day ,,series4 ,illustrated4 #gs4 #f;d4 nett each4 ,,scientific ,,ideas ,,of ,,to-,,day4 ,a ,popular ,account of the ,nature of ,matter1 ,electricity1 ,light1 ,heat1 c4 c4 8,explained without big words1 with many interesting pictures1 and with an ease in exposition40--,scotsman4 ,,electricity ,,of ,,to-,,day2 ,its ,work and ,mysteries described in ,non-technical ,language4 ,with #cj ,illustrations4 8,a masterly work40--,globe4 ,,in ,,the ,,romance ,,library4 ,illustrated4 #fs4 nett each4 ,,the ,,romance ,,of ,,modern ,,electricity4 ,what is known about ,electricity and many of its interesting applications4 8,clear and concise40--,graphic4 ,,the ,,romance ,,of ,,modern ,,photography4 8,there is not a dry or uninteresting page throughout40--,country ,life4 8,the narration is everywhere remarkable for its fluency and clear style40--,bystander4 ,,the ,,romance ,,of ,,modern ,,manufacture4 8,a popular and practical account of all kinds of manufacture40--,scotsman4 ,,the ,,romance ,,of ,,scientific ,,discovery4 ,,heroes ,,of ,,the ,,scientific ,,world4 ,the ,lives1 ,sacrifices1 ,successes1 and ,failures of some of the greatest ,scientists4 ,with #ai ,illustrations4 8,the whole field of science is well covered4444 ,every one of the #cjj and odd pages contains some interesting piece of information40--,athenum4 ,,what ,,is ,,electricity4 ,long #hvo4 ,with #h ,illustrations4 #fs4 nett4 8,a brilliant study40--,daily ,mail4 8,quite a unique book in its way1 at once attractive and illuminating40--,record4 ,,the ,,marvels ,,of ,,photography4 ,illustrated4 #es4 nett4 ,,in ,,the ,,wonder ,,library4 ,illustrated4 #cs4 nett each4 ,,the ,,wonders ,,of ,,modern ,,manufacture4 ,,the ,,wonders ,,of ,,war ,,inventions4 ,,the ,,wonders ,,of ,,modern ,,electricity4 ,with #ag ,illustrations and ,diagrams4 ,,wireless ,,telegraphy4 ,a ,popular ,description of ,wireless ,telegraphy and ,telephony in which no technical terms are used1 and no previous knowledge of the subject assumed4 #cs4 #f;d4 nett4 99 99 99 99 99 ,,the ,,science ,,of ,,to-,,day ,,series ,with many ,illustrations4 ,extra ,crown #hvo4 #gs4 #f;d4 nett ,,new ,,volume ,,submarine ,,warfare ,,of ,,to-,,day4 ,telling how the ,submarine ,menace was met vanquished4 ,by ,c4 ,w4 ,,domville-,,fife1 ,staff of ,h4,m4 ,school of ,submarine ,mining4 ,with #ec ,illustrations4 8,a very striking book1 revelation follows revelation1 and magnificent stories of fighting heroism at sea come practically on every page4 ,one of the few war books which will survive the next #aj years40--,liverpool ,courier4 ,,aircraft ,,of ,,to-,,day4 ,a ,popular ,account of the ,conquest of the ,air4 ,by ,,maj4 ,,charles ,c4 ,,turner1 ,r4,a4,f4 ,with #fb ,illustrations4 8,maj4 ,turner is well known as an authority on aeronautics4 ,of real value40--,aberdeen ,journal4 ,,geology ,,of ,,to-,,day4 ,a ,popular ,introduction in ,simple ,language4 ,by ,j4 ,w4 ,,gregory1 ,f4,r4,s41 ,d4,sc41 ,professor of ,geology at the ,university of ,glasgow4 ,with #ee ,illustrations4 ,extra ,crown #hvo4 8,an ideal introduction to a fascinating science4 ,the romance and reality of the earth most brilliantly and soundly presented40--,globe4 ,,submarine ,,engineering ,,of ,,to-,,day4 ,by ,c4 ,w4 ,,domville-,,fife1 ,author of 8,submarines of the ,world's ,navies10 c4 ,,botany ,,of ,,to-,,day4 ,a ,popular ,account of the ,evolution of ,modern ,botany4 ,by ,prof4 ,g4 ,f4 ,,scott-,,elliot1 ,m4,a41 ,b4,sc41 ,f4,l4,s4 8,this most entertaining and instructive book4 ,it is the fruit of wide reading and much patient industry40--,globe4 ,,scientific ,,ideas ,,of ,,to-,,day4 ,a ,popular ,account1 in ,non-technical ,language1 of the ,nature of ,matter1 ,electricity1 ,light1 ,heat1 ,electrons1 c4 c4 ,by ,c4 ,r4 ,,gibson1 ,f4,r4,s4,e4 ,extra ,crown #hvo4 8,as a knowledgeable writer1 gifted with the power of imparting what he knows in a manner intelligible to all1 ,mr4 ,c4 ,r4 ,gibson has established a well-deserved reputation40--,field4 ,,astronomy ,,of ,,to-,,day4 ,a ,popular ,introduction in ,non-technical ,language4 ,by ,,cecil ,g4 ,,dolmage1 ,,ll4,d41 ,f4,r4,a4,s4 #df ,illustrations4 ,extra ,crown #hvo4 8,a lucid exposition much helped by abundant illustrations40--,the ,times4 ,,electricity ,,of ,,to-,,day4 ,its ,work and ,mysteries ,explained4 ,by ,,charles ,r4 ,,gibson1 ,f4,r4,s4,e4 ,extra ,crown #hvo4 8,one of the best examples of popular scientific exposition that we remember seeing40--,the ,tribune4 ,,engineering ,,of ,,to-,,day4 ,a ,popular ,account of the ,present ,state of the ,science4 ,by ,t4 ,w4 ,,corbin4 #ci ,illustrations4 ,ex4 ,cr4 #hvo4 8,most attractive and instructive40--,record4 ,,medical ,,science ,,of ,,to-,,day4 ,a ,popular ,account of recent ,developments4 ,by ,,willmott-,,evans1 ,m4,d41 ,b4,sc41 ,f4,r4,c4,s4 8,a very ,golconda of gems of knowledge40--,manchester ,guardian4 ,,mechanical ,,inventions ,,of ,,to-,,day4 ,an ,interesting ,description of ,modern ,mechanical ,inventions4 ,by ,,thomas ,w4 ,,corbin4 8,in knowledge and clearness of exposition it is far better than most works of a similar character and aim40--,academy4 ,,photography ,,of ,,to-,,day4 ,a ,popular ,account of the ,origin1 ,progress1 and ,latest ,discoveries4 ,by ,h4 ,,chapman ,,jones1 ,f4,i4,c41 ,f4,c4,s41 ,pres4 ,r4,p4,s42 ,lecturer on ,photography at ,imperial ,college of ,science4 8,an admirable statement of the development of photography from its very beginning to the present time40--,journal of ,photography4 ,,seeley1 ,,service ,,co41 ,,limited 99 99 99 99 99 ,,the ,,romance ,,of ,,the ,,microscope 99 99 99 99 99 ,illustration3 ,by the courtesy of ,messrs4 ,f4 ,davidson ,co4 ,,an ,,example ,,of ,a ,,micro-,,telescopic ,,photograph 8,nanda ,kot40 ,height1 #bb1eaj feet2 distance1 #fj miles4 ,the trees at the lower right-hand corner are only #bj yards from the photographer4 ,a remarkable photograph1 showing the great depth of focus of the micro-telescope4 99 99 99 99 99 ,,the ,,romance ,,of ,,the ,,microscope ,,an ,,interesting ,,description ,,of ,,its ,,uses ,,in ,,all ,,branches ,,of ,,science1 ,,industry1 ,,agriculture1 ,,and ,,in ,,the ,,detection ,,of ,,crime1 ,,with ,a ,,short ,,account ,,of ,,its ,,origin1 ,,history ,,development4 ,,by ,c4 ,a4 ,,ealand1 ,m4,a4 ,,author ,,of 8,,animal ,,ingenuity ,,of ,,to-,,day10 8,,insects ,,and ,,man10 ,c41 ,c4 ,,with #ci ,,illustrations ,,numerous ,,diagrams ,,london ,,seeley1 ,,service ,,co4 ,,limited #ch ,,great ,,russell ,,street #aiba 99 99 99 99 99 ,,uniform ,,with ,,this ,,volume ,,the ,,library ,,of ,,romance ,extra ,crown #hvo4 ,with many illustrations4 #fs4 nett4 8,splendid ,volumes40--,the ,outlook4 8,the ,library of ,romance offers a splendid choice40--,globe4 8,gift ,books whose value it would be difficult to over-estimate40--,the ,standard4 8,this series has now won a considerable well deserved reputation40--,the ,guardian4 8,each ,volume treats its allotted theme with accuracy1 but at the same time with a charm that will commend itself to readers of all ages4 ,the root idea is excellent1 and it is excellently carried out1 with full illustrations and very prettily designed covers40--,the ,daily ,telegraph4 ,by ,prof4 ,g4 ,f4 ,,scott ,,elliot1 ,m4,a41 ,b4,sc4 ,the ,romance of ,savage ,life ,the ,romance of ,plant ,life ,the ,romance of ,early ,british ,life ,by ,,edward ,,gilliat1 ,m4,a4 ,the ,romance of ,modern ,sieges ,by ,,john ,,lea1 ,m4,a4 ,the ,romance of ,bird ,life ,by ,,john ,,lea1 ,m4,a4 ,h4 ,,coupin1 ,d4,sc4 ,the ,romance of ,animal ,arts and ,crafts ,by ,,sidney ,,wright ,the ,romance of the ,world's ,fisheries ,by the ,rev4 ,j4 ,c4 ,,lambert1 ,m4,a41 ,d4,d4 ,the ,romance of ,missionary ,heroism ,by ,g4 ,,firth ,,scott ,the ,romance of ,polar ,exploration ,by ,,charles ,r4 ,,gibson1 ,f4,r4,s4,e4 ,the ,romance of ,modern ,photography ,the ,romance of ,modern ,electricity ,the ,romance of ,modern ,manufacture ,the ,romance of ,scientific ,discovery ,by ,,charles ,c4 ,,turner ,the ,romance of ,aeronautics ,by ,,hector ,,macpherson1 ,junr4 ,the ,romance of ,modern ,astronomy ,by ,,edward ,,bennett ,the ,romance of the ,post ,office4 ,by ,,archibald ,,williams1 ,b4,a4 7,oxon471 ,f4,r4,g4,s4 ,the ,romance of ,early ,exploration ,the ,romance of ,modern ,exploration ,the ,romance of ,modern ,mechanism ,the ,romance of ,modern ,invention ,the ,romance of ,modern ,engineering ,the ,romance of ,modern ,locomotion ,the ,romance of ,modern ,mining ,by ,,edmund ,,selous ,the ,romance of the ,animal ,world ,the ,romance of ,insect ,life ,by ,,agnes ,,giberne ,the ,romance of the ,mighty ,deep ,by ,e4 ,s4 ,,grew1 ,m4,a4 ,the ,romance of ,modern ,geology ,by ,j4 ,c4 ,,philip1 ,d4,sc41 ,ph4,d4 ,the ,romance of ,modern ,chemistry ,by ,e4 ,,keble ,,chatterton1 ,b4,a4 ,the ,romance of the ,ship ,the ,romance of ,piracy ,by ,t4 ,w4 ,,corbin ,the ,romance of ,submarine ,engineering ,the ,romance of ,war ,inventions ,by ,,norman ,j4 ,,davidson1 ,b4,a4 7,oxon47 ,the ,romance of the ,spanish ,main ,by ,h4 ,o4 ,,newland1 ,f4,r4,hist4,s4 ,the ,romance of ,modern ,commerce4 ,,seeley1 ,,service ,,co41 ,,limited4 99 99 99 99 99 ,,contents ,,chapter ,i ,,page ,,early ,,days ,,of ,,the ,,microscope #ag ,,chapter ,,ii ,,some ,,early ,,microscopists #bi ,,chapter ,,iii ,,the ,,action ,,of ,,light #dj ,,chapter ,,iv ,,the ,,compound ,,microscope #ej ,,chapter ,v ,,animal ,,life ,,in ,,ponds ,,and ,,streams #ff ,,chapter ,,vi ,,plant ,,life ,,in ,,ponds ,,and ,,streams #hc ,,chapter ,,vii ,,the ,,microscope ,,and ,,plant ,,life #ig ,,chapter ,,viii ,,animal ,,life ,,and ,,the ,,microscope #aab ,,chapter ,,ix ,,the ,,study ,,of ,,the ,,rocks #abe ,,chapter ,x ,,the ,,microscope ,,as ,,detective #acg ,,chapter ,,xi ,,bacteria #aeb ,,chapter ,,xii ,,medical ,,work ,,with ,,the ,,microscope #afg ,,chapter ,,xiii ,,the ,,microscope ,,and ,,agriculture #agh ,,chapter ,,xiv ,,the ,,microscope ,,and ,,insect ,,life #aib ,,chapter ,,xv ,,the ,,microscope ,,by ,,the ,,seaside--,,animal ,,life #bjh ,,chapter ,,xvi ,,the ,,microscope ,,by ,,the ,,seaside--,,plant ,,life #bbe ,,chapter ,,xvii ,,micro-,,telescope ,,and ,,super ,,microscope #bci ,,chapter ,,xviii ,,chemistry ,,and ,,the ,,microscope #bdh ,,chapter ,,xix ,,use ,,of ,,the ,,microscope ,,in ,,manufactures #bfj ,,chapter ,,xx ,,the ,,microscope ,,and ,,camera ,,allied #bgd ,,chapter ,,xxi ,,how ,,the ,,glass ,,used ,,in ,,microscopes ,,is ,,made #bhb ,,chapter ,,xxii ,,the ,,choice ,,and ,,use ,,of ,,apparatus #bia ,,list ,,of ,,illustrations ,,page ,,nanda ,,kot--,,an ,,example ,,of ,,tele-,,photography ,frontispiece ,,head ,,of ,,dog ,,flea #ef ,,starch ,,grains ,,of ,,potato #gb ,,phosphorescence ,,animalcul #gb ,,proteus ,,animalcule #gb ,,cyclops #gb ,,bladderwort #hh ,,spores ,,of ,,horse-,,tail #hh ,,hairs ,,on ,a ,,potato ,,leaf #hh ,,spirogyra #hh ,,thorn ,,insect #abj ,,head ,,of ,,palm ,,weevil #abj ,,leaf ,,insect #abj ,,head ,,of ,,stick ,,insect #abj ,,foraminifera #abh ,,diatoms #abh ,,stinging ,,hairs ,,of ,,nettle #add ,,butterfly ,,wing ,,scales #add ,,crystals ,,from ,,human ,,blood #afh ,,crystals ,,from ,,the ,,blood ,,of ,,the ,,baboon #afh ,,cluster ,,cups #ahd ,,rust ,,of ,,wheat #ahd ,,pollen ,,grains ,,on ,a ,,grass ,,flower #ahd ,,lower ,,side ,,of ,a ,,fern ,,frond #ahd ,,head ,,of ,a ,,beetle #bjj ,,head ,,of ,,hercules ,,beetle #bjj ,a ,,cicada #bjj ,,head ,,of ,,mantis #bjj ,,face ,,of ,a ,,fly #baf ,,section ,,of ,,human ,,skin #baf ,,feeler ,,of ,,cockchafer #bcb ,,view ,,with ,,ordinary ,,camera #bdj ,,view ,,with ,,micro-,,telescope #bdj ,,eye ,,of ,a ,,cockchafer #bef ,,hooks ,,on ,a ,,bee',s ,,wing #bef ,,spider',s ,,foot #bfd ,,fly',s ,,foot #bfd ,,fly',s ,,eye #bif ,,images ,,seen ,,by ,a ,,fly #bif 99 99 99 99 99 ,the ,romance of the ,microscope ,,chapter ,i ,,the ,,early ,,days ,,of ,,the ,,microscope ,it is certain that lenses were used as early as the thirteenth century1 and it is probable that they date back to far earlier times4 ,the ancient gem cutters probably used spheres of glass filled with water as magnifiers1 their work could hardly have been accomplished without some artificial aid4 ,we know1 from early writings1 that burning glasses were used by physicians in their work1 and ,seneca1 the author1 who wrote in ,a4,d4 #fc1 says3 8,letters1 however small and dim1 are comparatively large and distinct when seen through a glass globe filled with water40 ,euclid1 whose name at least is familiar to everyone1 was1 as shown by his writings1 perfectly well acquainted with the fact that curved mirrors may be used to magnify objects1 and that was so long ago as the third century ,b4,c4 ,convex glasses1 used as spectacles1 were first mentioned by ,bernard de ,gordon1 about #acjg1 but1 as far as we know1 they were never used for the purpose of studying minute living objects4 ,to ,leonardo da ,vinci belongs the honour of seriously investigating1 for the first time1 the properties of concave and convex lenses1 and several alchemists1 as the early chemists were called1 used flasks filled with water1 concave mirrors or glass balls to gather together the rays of the sun4 8,long before the dawn of the seventeenth century1 the principle of the lens was both comprehended and applied to scientific matters by the ,englishmen1 ,leonard ,digges and his son ,thomas1 and by the ,italian1 ,giambattista ,porta40 ,towards the end of the sixteenth century and the early part of the seventeenth century1 interest in the minute structure of natural objects appears to have developed4 ,as early as #aeij1 ,thomas ,mouffet used magnifying glasses in studying small mites1 and in #afcg ,descartes invented a single lens microscope in which the rays of light were reflected on to the object by means of a concave mirror4 ,this method of illumination1 it is interesting to note1 is still used in some forms of pocket magnifiers4 ,most of the early discoveries were made with single lenses1 for in the compound microscopes which were first made1 it was only possible to view such a small portion of an object at one time that the advantage lay with the less complicated instrument4 ,the earliest microscopes were simply short tubes of any material which would not admit light2 at one end there was a lens1 at the other a glass plate on which the object to be examined was placed4 ,because these crude instruments were chiefly used for the examination of insects they were known as 8,vitrea pulicaria0 or 8,vitrea muscaria40 ,later they were called 8,engyoscopes10 and1 after the invention of compound microscopes1 they were described as 8,microscopia ludicra10 as opposed to the latter instruments1 known as 8,microscopia seria40 ,the next stage in the development of the microscope consisted in the introduction of lenses of very short focal length1 and1 in #affe1 ,robert ,hooke used small glass balls1 formed by fusing threads of drawn glass1 for this purpose4 ,it was ,antony van ,leeuwenhoek1 however1 who perfected these instruments4 ,he brought an extraordinary skill and industry to bear on the grinding and polishing of minute lenses of short focal length4 ,already in #afgc ,regnier de ,graaf wrote to the ,royal ,society in ,london that ,leeuwenhoek was making glasses far superior to those of the great ,italian lens maker1 ,eustachio ,divini4 ,leeuwenhoek's success was largely due not only to his method of grinding1 but also to the skill with which he mounted his lenses1 which were accurately fitted into a minute hole in a metal plate4 ,the object to be examined was firmly held in a stand and adjusted by means of a screw movement4 ,by this means1 and by the use of hollow metal reflectors1 he succeeded in availing himself of transmitted light in the case of transparent objects4 ,leeuwenhoek was able to make immense advances with these instruments1 the minute pond animals he could see with ease1 and by #afhc he had even attained a sight of the bacteria4 ,his researches represented the high-water mark of work done with the simple microscope1 most of the later work was carried out with the compound instrument4 ,the earliest history of the compound microscope is difficult to separate from that of the telescope and1 in any complete account1 the two instruments must be considered together4 ,it appears that the first scientist that conceived the idea of using a series of lenses1 rather than a single lens1 was ,leonard ,digges1 whom we have already mentioned4 ,in a book by ,porta1 a writer who though not himself original1 was gifted with great curiosity and industry in the collection of the ideas of others1 we read3 8,how to make plain a letter held far away by means of a lens of crystal10 and also that 8with a concave lens you see things afar smaller but plainer1 with a convex lens you see them larger but less distinct4 ,if1 however1 you know how to combine the two sorts properly you will see near and far both large and clear40 ,shortly after the publication of ,porta's book the method of combining two lenses into a microscope or telescope was discovered1 quite accidentally1 by a ,dutch boy named ,zacharias1 who worked in the shop of his father1 a spectacle maker4 ,the event was described by ,willem ,boreel1 ,dutch ,ambassador to ,france1 in a letter written in #afee4 ,he wrote3 8,i am a native of ,middleburg1 the capital of ,zeeland1 and close to the house where ,i was born1 there lived in the year #aeia a certain spectacle maker1 ,hans by name4 ,his wife1 ,maria1 had a son1 ,zacharias1 whom ,i knew very well1 because ,i constantly as a neighbour and from a tender age went in and out playing with him4 ,this ,hans or ,johannes with his son ,zacharias1 as ,i have often heard1 were the first to invent microscopes1 which they presented to ,prince ,maurice1 the governor and supreme commander of the ,united ,dutch forces1 and were rewarded with some honorarium4 ,similarly they afterwards offered a microscope to the ,austrian ,archduke ,albert1 supreme governor of ,holland4 ,when ,i was ,ambassador to ,england in the year #afai1 the ,dutchman ,cornelius ,drebbel of ,alkomar1 a man familiar with many secrets of nature1 who was serving there as a mathematician to ,king ,james1 and was well known to me1 showed me that very instrument which the ,archduke had presented as a gift to ,drebbel1 namely1 the microscope of ,zacharias himself4 ,nor was it 7as they are most seen7 with a short tube1 but nearly two and a half feet long1 and the tube was of gilded brass two fingers' breadth in diameter1 and supported on three dolphins formed also of brass4 ,at its base was an ebony disc1 containing shreds or some minute objects which we inspected from above1 and their forms were so magnified as to seem almost miraculous40 ,so this was the first compound microscope6 ,although ,zacharias invented the microscope1 it was ,galileo who introduced it to the scientific world4 ,he published a book in #afaj in which he wrote3 8,about ten months ago a rumour reached me of an ocular instrument made by a certain ,dutchman1 by means of which an object could be made to appear distinct and near to an eye that looked through it1 although it was really far away4 ,and so ,i considered the desirability of investigating the method1 and reflected on the means by which ,i might come to the invention of a similar instrument4 ,i first prepared a leather tube at the ends of which one placed two lenses each of them flat on one side1 and as to the other side ,i fashioned one concave and the other convex4 ,then holding the eye to the concave one1 ,i saw the objects fairly large and nearer1 for they appeared three times nearer and nine times larger than when they were observed by the naked eye4 ,soon after ,i made another more exactly1 representing objects more than sixty times larger4 ,at length1 sparing no labour and no expense1 ,i got to the point that ,i could construct an excellent instrument so that things seen through it appeared a thousand times greater and more than thirty-fold nearer than if observed by the naked eye40 ,galileo had his enemies1 who accused him of having picked ,zacharias's brains2 he admitted that he had taken his idea from the ,dutchman's invention1 but further than that he would not go2 in fact1 he replied that the invention of ,zacharias was a mere accident but that his own instrument was discovered by a process of reasoning4 ,it would serve no good purpose to tell the story of all the scientists who have helped to bring the microscope to its present state of perfection1 although many of their descriptions of objects and apparatus are as quaint as the latter4 ,scheiner1 for example1 who wrote in #afcj1 mentions 8that wonderful instrument the microscope1 by means of which a fly is magnified into an elephant1 and a flea into a camel40 ,to ,kircher belongs the credit of being the first worker to construct an instrument with coarse and fine adjustment and with a substage condenser1 which could be used either for concentrating the sun's rays or those from a lamp4 ,with an instrument of this pattern ,malpighi saw the circulation of blood in a frog's lung4 ,by #afhe1 when instruments with four and six lenses were being used1 the compound microscope was firmly established as a help to scientists1 and the simple lens was used thereafter as an adjunct but not a rival to the newer instrument4 ,history makes a strong appeal to many people1 and those who are fascinated thereby will find endless amusement in reading old books on the microscope and its objects4 ,in the preface to ,mouffet's ,insectorum ,theatrum1 one of the earliest books on insects1 we read the following quaint lines3 8,if you will take lenticular object glasses of ,crystal 7for though you have ,lynx his eyes1 they are necessary in searching for atoms7 you will admire to see the ,fleas that are curasheers1 and their hollow trunk to torture men1 which is a bitter plague to maids1 you shall see the eyes of ,lice sticking forth1 and their horns1 their bodies crammed all over1 their whole substance diaphanous1 and through that1 the motion of their heart and blood4 ,also little ,handworms1 which are indivisible1 they are so small1 being with a needle prickt forth from their trenches near the pool of water which they have made in the skin1 and being laid upon one's nail1 will discover by the sunlight their red heads and feet they creep withal40 ,the creatures called ,handworms are itch mites1 which tunnel in the human skin4 ,in our chapter on ,nature ,study and the ,microscope we refer to the brown patches to be found on the backs of fern fronds2 it is interesting to note that so long ago as #afdf ,sir ,thomas ,browne had quite a good idea of their structure4 ,describing them1 he said3 8,whether these little dusty particles1 upon the lower side of the leaves be seeds we have not yet been able to determine by any germination4 ,but1 by the help of magnifying glasses we find these dusty atoms to be round at first and fully representing seeds out of which at last proceed little mites1 almost invisible1 so that such as are old stand open1 as being emptied of some bodies firstly included1 which though discernible in ,hartstongue1 is more notoriously discoverable1 in some differences1 of ,brake or ,fern40 ,two years earlier a noted scientist1 ,hodierna1 had made a special study of the eyes of insects and1 considering the crude instruments with which he must have worked1 his descriptions are wonderfully accurate4 ,of the house fly he wrote3 8,the head is all eyes1 prominent and without lids1 lashes or brows4 ,it is plumed with hairs like that of an ostrich and has two little pear shaped bodies hanging from the middle of the forehead4 ,the proboscis which arises from the snout can be extended freely and stretched forth to suck up humours and can afterwards be directed back through the mouth and taken into the gullet4 ,this instinct nature has given the creature according to its need1 for it is without a neck and cannot stretch forth its head to obtain its food1 as is also the case with the elephant40 ,the author's knowledge of the house fly was evidently greater than his knowledge of the ostrich1 for the bird has anything but a plumed head4 ,the eye of the insect he compares to a white mulberry4 ,another of these early workers1 writing about the same time1 gives a concise account of cheese mites1 heading his description 8,on the creatures which arise in powdery cheese10 he wrote3 8,the powder examined by means of this instrument 7the ,compound ,microscope7 does not present the aspect of dirt1 but teems with animalcula4 ,it can be seen that these creatures have claws and talons and are furnished with eyes4 ,the whole surface of their body is beautifully and distinctly coloured in such sort as ,i have never seen before1 and which indeed1 cannot be seen without wonder4 ,they may be observed to crawl1 eat and work and are equal in apparent size to a man's nail4 ,their backs are all spiny and pricked out with various starlike markings and surrounded by a rampart of hairs1 all of such marvellous kind that you would say they are a work of art rather than of nature40 ,at about this period the microscope was used for the first time for medical work and1 as far as can be ascertained1 ,pierre ,borel was the first to use it for this purpose1 and he learned a great deal about the structure of flesh and the appearance of blood4 ,of all the early writers on microscopy the man who spread abroad his knowledge of the instrument and its capabilities1 more than anyone else1 was ,kircher1 who died in #afhj4 ,he was an energetic writer1 and wrote on a large number of subjects4 ,his books dealt with magnetism1 designs for a calculating machine1 light1 sound1 history of plague1 the philosopher's stone1 ,egyptian antiquities1 a history of ,china and a grammar4 ,to all who read his book on the plague1 it is clear that he had a good idea of infection2 he was1 in fact1 the first writer who suspected it1 though the microscope he used could not show him bacteria4 ,in his book he wrote3 8,everyone knows that decomposing bodies breed worms1 but only since the wonderful discovery of the microscope has it been known that every putrid body swarms with innumerable vermicules1 a statement which ,i should not have believed had ,i not tested its truth by experiments during many years40 ,the experiments he performed to prove his statement are so quaint that we give them in his own words4 ,experiment ,i4--8,take a piece of meat which you have exposed by night until the following dawn to the lunar moisture4 ,then examine it carefully with the smicroscope and you will find the contracted putridity to have been altered by the moon into innumerable wormlets of diverse size1 which1 however1 would escape the sharpness of vision without a good smicroscope4 ,the same is true of cheese1 milk1 vinegar and similar bodies of a putrifiable nature4 ,the smicroscope1 however1 must be no ordinary one1 but constructed with no less skill than diligence1 as is mine which represents objects one thousand times greater than their true size40 ,experiment ,,ii4--8,if you cut up a snake into small parts and macerate with rain water1 and then expose it for several days to the sun and again bury it under the earth for a whole day and night and lastly examine the parts1 separated and softened by putridity1 by means of a smicroscope you will find the whole mass swarm with innumerable little multiplying serpents so that even the sharpest eyes cannot count them40 ,experiment ,,iii4--8,many authors claim that unwashed sage is injurious1 but ,i have discovered the cause of this4 ,for when1 by means of the sun1 ,i minutely examined the nature of the plant1 ,i found the back of the leaves completely covered by raised work as with the figure of a spider's web1 and within the water appeared infinitesimal animalcules1 which moving constantly came out of little buds or eggs40 ,experiment ,,iv4--8,if you examine a particle of rotten wood under the sun1 you will see an immense progeny of tiny worms1 some with horns1 some with wings1 others with many feet4 ,they have little black dots of eyes4 ,what must their little livers and stomachs be like80 ,in the light of modern discovery much of the writing of these early microscopists seems absurd4 ,kircher's experiments1 for example1 prove nothing1 and he is often hopelessly vague and sometimes incorrect in his statements4 ,we must not be too critical1 however1 for some of this early work was excellent1 the microscopes in use would not be tolerated at the present day1 and without these pioneers microscopy would not have reached the stage it has4 ,rather than laugh at their efforts1 we should marvel that they did so well4 ,,chapter ,,ii ,,some ,,early ,,microscopists ,of the early ,british microscopists1 ,robert ,hooke must not pass unnoticed4 ,he was appointed ,curator of the ,royal ,society two years after its formation1 and the terms of his appointment were somewhat one-sided4 ,he was required to 8furnish the ,society every day they meet with three or four experiments02 for this no pay was to be his till the ,society accumulated sufficient funds to reward him4 ,although compound microscopes had been invented in ,hooke's day1 it is noteworthy that he remained faithful to the single lens1 in fact it was not till very many years later that the simple lens was supplanted1 in general use by the more complicated1 if more perfect instrument4 ,in his book on ,microscopy1 entitled ,micrographia1 ,hooke gives a quaint account of the making of a microscope4 8,could we make a microscope10 he writes1 8to have only one refraction1 it would cteris paribus1 far excel any other that had a greater number4 ,and hence it is1 that if you take a very clear piece of a broken ,venice glass1 and in a ,lamp draw it out into very small hairs or threads1 then holding the ends of these threads in the flame1 till they melt and run into a small round ,globul1 or drop1 which will hang at the end of the thread2 and if further you stick several of these upon the end of a stick with a little sealing wax1 so that the threads stand upwards1 and then on a whetstone first grind off a good part of them1 and afterward on a smooth ,metal plate1 with a little ,tripoly1 rub them till they come to be very smooth2 if one of these be fixt with a little soft wax against a small needle hole1 prick'd through a thin ,plate of ,brass1 ,lead1 ,pewter1 or any other ,metal1 and an ,object1 plac'd very near1 be look'd at through it1 it will both magnifie and make some ,objects more distinct than any of the great ,microscopes40 ,this early worker was noted for the variety of his investigations rather than for the depths of his learning4 ,amongst the so-called ,observations1 in his book are many that are not connected with microscopic work4 ,the following are interesting and1 in the curious old book ,micrographia1 there are an extraordinary number of well executed illustrations4 ,early in his book ,hooke compares various man-made objects1 such as a razor edge1 the point of a needle and a piece of cloth1 with various natural objects1 and always to the detriment of the former4 ,he examined ,foraminifera with his microscope1 and was probably the first man to draw these beautiful little creatures4 ,petrified wood and charcoal also came under his notice4 ,when he studied cork1 he observed that it was made up of 8little boxes or cells10 and the name cell has survived to this day despite the fact that it is by no means an appropriate term4 ,that ,hooke's knowledge was not very deep is shown by the fact that he presumed cork to be a fungus growing on the bark of trees4 ,many of the objects we have described in our pages were described and illustrated by ,hooke more than two hundred years ago4 ,the sea mat1 despite his accurate observations1 he mistook for a seaweed1 as many later naturalists have done4 ,the stinging hairs of nettle he made out in every detail4 ,fish scales1 bee stings and birds' feathers all came under his notice4 ,the foot of a fly he described with wonderful accuracy2 the scales of a butterfly's wing and the head of a fly were all studied and described in detail4 ,on the life history of the gnat he made many blunders1 but he saved his reputation by remarkable observations upon the ,chelifer1 a curious parasite of the fly which we mention in our pages1 and upon the silver fish1 a little creature which frequents sugar and starch4 ,neither of these organisms had been described before4 ,fleas1 lice1 vinegar-eels and spiders were also studied by this indefatigable worker1 a worthy collection indeed1 but ,hooke1 like others of his time1 was an observer first and foremost4 ,as a methodical1 scientific worker he was of little account4 ,living about the same time as ,hooke1 the celebrated ,italian1 ,malpighi1 laid the foundations of much of our present-day knowledge of plant structure4 ,various romantic stories have been told concerning certain imaginary events which led ,malpighi to take up the study of plant structure1 but the scientist himself refuted these picturesque stories4 ,suffice it to say that his book on the subject1 ,anatome ,plantarum1 though imperfect in many respects and1 as might be conjectured in so early a work1 often inaccurate1 contains a large number of astonishingly good drawings2 many of the original drawings1 by the way1 executed in red chalk1 are in the possession of the ,royal ,society4 ,it is interesting to note that this botanist compared the falling of leaves to the shedding of an insect's skin1 in this respect at any rate he had advanced no further than ,aristotle1 who compared leaf-fall to the moulting of a bird4 ,on the other hand1 the ,italian was the first scientist to describe the pores 7stomata7 of leaves1 though he never discovered that they occurred on all leaves4 ,he1 first of all men1 showed that nectar was formed by the flower and not transferred thence from other sources as had previously been believed2 he too explained accurately for the first time the process of germination in the seed4 ,it was not alone as a botanist1 however1 that ,malpighi was celebrated4 ,he elucidated the various changes which take place during the hatching of an egg2 he was the first man to give an accurate account of the structure of an insect1 and this he did in his work on the ,anatomy of the ,silkworm4 ,using a simple microscope for his investigations1 he contracted an eye affliction during this period from which he suffered more or less severely all the rest of his life4 ,he discovered the breathing tubes of insects and that when they are covered with grease the insect will die 8in the time that one can say the ,lord's ,prayer02 the heart1 the silk glands1 the development of wings and legs were all discovered for the first time by this untiring worker1 aided by his simple microscope4 ,pages could be filled with accounts of ,malpighi's other scientific work on the structure of the lung1 the liver and kidney1 the life of the liver fluke and a hundred and one other subjects4 ,though undoubtedly a great and clever microscopist1 the general estimate seems to be that his work had little influence upon the scientific world4 ,the main reason is that he was ahead of his time2 men of the day concluded1 for instance1 that in his ,anatomy of ,plants he had said the last word on the subject1 that there was no more to be learned4 ,an ,english worker1 ,nehemiah ,grew1 carried the ,italian scientist's studies of plant structure a little further and his ,anatomy of ,plants contains many new and often accurate observations4 ,his studies also led him to discover the structure of the ridges and sweat pores of the human hand1 in fact ,grew may be looked upon as the originator of the study of finger prints4 ,a ,dutchman1 ,jan ,jacobz ,swammerdam by name1 and a contemporary of ,grew1 was undoubtedly the most accurate observer amongst these old-time microscopists4 ,despite ill health1 his enthusiasm was unbounded1 and a friend wrote concerning him3 8,swammerdam's labours were superhuman4 ,through the day he observed incessantly1 and at night described and drew what he had seen4 ,by six o'clock in the morning in summer he began to find enough light to enable him to trace the minuti of natural objects4 ,he was hard at work till noon1 in full sunlight1 and bareheaded1 so as not to obstruct the light1 and his head steamed with profuse sweat4 ,his eyes1 by reason of the blaze of light1 became so weakened that he could not observe minute objects in the afternoon1 for his eyes were weary40 ,if only for the fact that the ,dutchman made clear the processes involved in the transformations of insects1 his name would be famous4 ,he described the structure and habits of the hive bees1 male1 female and drone with wonderful accuracy1 and illustrated his work with plates which 8would do credit to the most skilful anatomists of any age40 ,swammerdam was sarcastic at times2 he had shown that the facets of a bee's eye are six-sided and1 as so commonly happened in those days1 some naturalists jumped to a conclusion1 in this case that the fact explained the six-sidedness of the cells in the honey comb4 ,by the same reasoning ,swammerdam remarked that men1 having round pupils1 should build round houses4 ,it is not only for his study of the minute structure of insects that this microscopist is noted1 he worked upon the tadpole and the snail4 ,he it was who discovered the red blood corpuscles of the frog1 and he described his discovery in the following terms3 8,in the blood ,i perceived the serum in which floated an immense number of rounded particles1 possessing the shape of1 as it were1 a flat oval1 but nevertheless wholly regular4 ,these particles seemed1 however1 to contain within themselves the humour#a of other particles4 ,when they were looked at sideways1 they resembled transparent rods1 as it were1 and many other figures1 according1 no doubt1 to the different ways in which they were rolled about in the serum of the blood4 ,i remarked besides that the colour of the objects was the paler the more highly they were magnified by means of the microscope40 ,of the snail he made a number of strikingly accurate studies1 in all of which he was aided by his lenses1 so that it is the more remarkable that he considered snails to be insects4 ,leeuwenhoek1 another ,dutchman1 we have already mentioned in our previous chapter4 ,he of all men brought the simple microscope to its highest state of development4 ,his instruments were one of the sights of ,holland1 and many eminent personages made a point of seeing them4 ,though he had not the advantage of any scientific training and spoke no other language than his own1 he made some remarkable additions to the scientific knowledge of the time4 ,like ,hooke1 he was not a methodical worker1 he was impelled by an unbounded curiosity4 8,when we are inclined to disparage ,leeuwenhoek's hasty methods it is well to recollect that he initiated biological inquiries of the greatest interest1 e4g41 the parthenogenesis of aphids and the revivification of dried microscopic organisms1 while he gave the first notices1 or the first worth mention1 of rotifers1 ,hydra1 infusorians1 yeast cells and bacteria40 ,we may here explain the meaning of the term 8parthenogenesis of aphids40 ,the female aphids or green flies are able to bring forth generation after generation during the first two-thirds or so of each year without the assistance of males4 ,this form of increase1 which by the way accounts for the extraordinary numbers of green fly1 is known as parthenogenesis4 ,leeuwenhoek thought that no one but himself could use his lenses properly1 in consequence1 when he sent any interesting object to a friend for him to examine1 a lens was always affixed in place so that the object could be seen to the best advantage4 ,he gave a set of his lenses and objects to the ,royal ,society1 and described his gift as 8a small black cabinet1 lackered and gilded1 which has five little drawers in it1 wherein are contained thirteen long and square tin boxes1 covered with black leather4 ,in each of these boxes are two ground microscopes1 in all six and twenty2 which ,i did grind myself1 and set in silver2 and most of the silver was what ,i had extracted from minerals1 and separated from the gold that was mixed with it2 and an account of each glass goes along with them40 ,kircher1 whose work we mentioned in our last chapter1 was overwhelmed with the notion that various living creatures are generated from non-living matter4 ,fleas1 for example1 he was certain1 came from dirt1 and it remained for ,leeuwenhoek to prove that they arise from eggs and grubs1 in the manner now so well understood4 ,he carefully studied the structure of a garden spider1 and for the first time explained its wonderful feet1 its jaws and poison gland1 its spinnerets and silk4 ,he studied ,hydra first of all men1 and said that1 under the microscope1 its tentacles appeared to be several fathoms long4 ,although sadly at sea over the correct position of his snails in the animal world1 he was clever enough to include ,volvox amongst the plants and fortunate enough to see the young forms escape from the parent colony4 ,concerning this microscopist's early studies in bacteriology we may quote from ,professor ,miall's ,the ,early ,naturalists1 a book by the way of the greatest interest to those who would learn something of the struggles of the men who laid the foundations of our present-day biological knowledge4 ,professor ,miall says3 8,in #afhc ,leeuwenhoek wrote a letter to the ,royal ,society which contains the first mention of bacteria4 ,he had been writing and speculating upon saliva1 and had searched the saliva of the human mouth for animalcules without finding any4 ,it then occurred to him to ask whether the teeth might lodge animalcules discharged from the salivary ducts4 ,he tells us that1 though his own teeth were scrupulously clean and particularly sound for his age 7about fifty71 the lens revealed a white deposit upon them4 ,this deposit was found to contain minute rods1 some of which showed either a steady or gyratory movement4 ,others were very minute1 of rounded form1 and moved with remarkable velocity4 ,the largest of all1 which were either straight or bent were motionless4 ,the teeth of an old man1 which were never cleansed1 contained among others large rods which exhibited snake-like undulations4 ,rubbing the teeth with strong vinegar did not kill the moving bodies1 but they became quiescent when detached and placed in a mixture of vinegar and saliva1 or vinegar and water4 ,nine years later ,leeuwenhoek returned to the subject4 ,living particles were no longer met with in his teeth1 and he was at a loss to explain why1 until it occurred to him that he was accustomed to drink hot coffee every morning4 ,this1 he thought might have killed the animalcules1 and his conclusion was confirmed by finding that on the back teeth1 which were less exposed to the hot drink1 plenty of them were still to be found4 ,in #afig he tells how he pulled out a decayed tooth1 and found that the cavity abounded in moving particles40 ,nearly a hundred years elapsed before anyone else took up the study of bacteria4 ,from the time of ,leeuwenhoek onwards1 scientific discoveries were announced in rapid succession1 so that in one short chapter it is impossible to keep pace with the progress that was made4 ,among the great men who owe much of their success to the microscope we may mention the ,frenchman ,raumur1 whose memory is kept green for all time by his thermometer2 as a worker upon problems of insect life he was indefatigable2 the ,swede1 ,linnus1 to whose early efforts we owe the orderly arrangement of living creatures and plants1 known as classification4 ,this arrangement has been considerably modified1 more modern ideas have upset much that he initiated1 yet he remains the parent of orderly arrangement4 ,buffon1 a great naturalist1 was followed by ,cuvier1 the first serious student of fossils2 by ,humboldt1 naturalist and traveller2 by ,robert ,brown1 the founder of modern ,botany2 by ,darwin and by ,pasteur in turn4 ,how much these men owe to the microscope can never be known2 certain it is that without its assistance our world1 the world we know and can see1 would have been smaller than it is to-day4 ,,footnote3 #a ,humour is here used in its original sense1 meaning moisture or a liquid4 ,,chapter ,,iii ,,the ,,action ,,of ,,light ,it is hardly necessary to remark that the wonderful properties of the microscope depend upon light4 ,without light1 lenses would be useless1 objects could not be illuminated and we could not see them4 ,in this short chapter we propose to give a brief outline of the action of light2 if our words appear to savour of the school-book1 we shall try to avoid it1 but1 we repeat1 if they do so we would remind our readers that the more one knows of the action of light the better use one can make of one's instrument4 ,as a well-known microscopist has remarked we may be able to afford a costly harp or a costly microscope1 but although we may be able to strike a few notes on the former and examine a few objects with the latter1 we can only make the best use of either by thoroughly understanding and practising upon it4 ,the first thing we learn when we study light is that it travels in straight lines4 ,the chief source of light to the inhabitants of this earth is the sun4 ,now the sun is so far away that1 for all practical purposes1 the rays of light coming from it may be looked upon as being parallel to one another4 ,that we must always remember1 when dealing with the sun1 though1 of course1 it does not apply when we are dealing with lights near at hand1 unless they are specially constructed to throw parallel beams or rays1 whichever we elect to call them4 ,to prove that light travels in straight lines is not difficult1 and we may devise a number of experiments for the purpose4 ,the doors and ventilators of many dark rooms1 in which photographic operations are carried on1 are constructed on the assumption that light cannot travel round corners4 ,an arrangement as shown in the diagram will allow air1 but no light1 to pass4 ,if light were capable of going round corners1 some other arrangement would have to be devised for the ventilation of dark rooms4 ,illustration ,having learned so much about light1 we come to the most important fact of all1 as far as the action of light concerns microscopic work4 ,when rays of light travel1 from a substance like air into a substance like water1 they are bent out of their straight course4 ,without any desire to introduce a number of unfamiliar words1 we may venture to remark that1 any substance through which light passes is called a medium4 ,some media are clearly more dense1 more compact or solid--dense is the proper word--than others4 ,water is more dense than air and glass than either4 ,the bending of light rays is known as refraction4 ,so now we may state our second law a little more concisely1 thus3--,when light passes from a medium into one more dense1 or vice versa1 it is refracted1 and the more dense the medium into which or from which the light passes the greater the refraction4 ,illustration ,a diagram and an experiment should make matters clear4 ,suppose ,,ab is a ray of light traveling in air and that it falls on a sheet of water1 ,,wxyz1 the ray will be bent along ,,bc and its course from air to water may be represented by ,,abc4 ,suppose again1 ,,wxyz represents1 not water but glass2 as glass is more dense than water the course of the ray ,,ab is represented by ,,abd1 it is refracted or bent to a greater extent than the ray which passed from air into water4 ,for our experiment we need only plunge a stick into water and notice that1 owing to this property of light1 the stick appears bent1 from the point where it comes into contact with the surface of the water4 ,illustration ,some of us may be old enough to remember that once1 on either corner of nearly every mantlepiece1 there stood an ornament of doubtful utility from which there hung a dozen or more glass prisms4 ,now the only beauty about these otherwise hideous contraptions was to be seen when light played upon them4 ,then patches of violet1 green1 yellow and red were thrown upon neighbouring objects4 ,white light1 ordinary sunlight that is to say1 is really composed of various colours--violet1 indigo1 blue1 green1 yellow1 orange and red--which1 when combined together1 make light as we know it4 ,when white light passes through a prism of glass1 it is not only bent out of its course1 but broken up into all these colours4 ,a prism1 as we all know1 when examined at either end1 is seen to be triangular in shape4 ,putting aside for a moment the question of the breaking up of light into its component parts1 the path of a ray of light through a prism is shown in the diagram4 ,as the ray passes from air into glass it is bent1 because glass is more dense than air2 it is bent once more on leaving the prism because air is less dense than glass4 ,illustration ,now lenses are made of various shapes1 and those with two outwardly curved surfaces are known as double convex lenses4 ,a double convex lens is usually made with both its surfaces equally curved and in the finer optical work great care is taken to ensure that this is the case4 ,for certain purposes1 however1 as we shall learn in a moment1 one or other of the faces only may be much more curved than its companion and this may be carried to such an extreme that one face is flat1 the lens is then known as plano-convex4 ,lenses may also have inwardly curved faces1 if both are of this design they are called double concave2 if one face is flat and the other inwardly curved they are known as plano-concave4 ,there are other combinations1 for example1 one face may be inwardly curved and the other outwardly curved1 but the four kinds we have described are all that need trouble us4 ,illustration ,it does not require a great amount of imagination to recognise that the double convex lens1 that is the lens with two outwardly curved faces is little more than a pair of prisms placed base to base1 or more accurately1 a number of prisms so arranged as shown in the diagram4 ,parallel rays of light falling upon such an arrangement of prisms would be bent from their course1 as shown by the arrows1 and this is just what happens with a double convex lens4 ,now rays of light from an object1 passing through a lens of this shape may follow any one of three courses1 according to the position of the object with regard to the lens4 ,in one position and one only the rays after passing through the lens will be parallel to one another1 as shown in the diagram4 ,the only position of the object for the above to take place is when it coincides with a point known as the principal focus of the lens1 conversely the parallel rays of light from the sun1 after passing through a double convex lens1 will come to a point at its principal focus4 ,suppose now that the object be placed at a point beyond the principal focus of the lens1 the light rays therefrom will1 after passing through the lens1 converge to a point thus3-- ,illustration ,in the diagram ,o is the object and ,p the principal focus of the lens4 ,the third case occurs where the object is nearer to the lens than its principal focus1 then the rays after passing through the lens1 diverge and never meet4 ,illustration ,we have already stated that when white light passes through a prism it is broken up into different coloured rays varying from violet to red4 ,the reason for this is that all the light rays composing white light are not bent equally as they pass from one medium to another4 ,the violet rays are bent the most1 the indigo next1 blue next1 down to red1 which is least bent4 ,once more1 considering the double convex lens as made up of a number of prisms1 let us represent1 by a diagram1 the course of parallel rays of white light through it4 ,illustration ,a ,a represent the parallel rays of white light falling on the lens1 ,l ,l4 ,the blue rays are bent more than the red1 so the principal focus of the former is at ,c and of the latter at ,d4 ,the consequence of this difference in bending of the various coloured light rays would be most serious in microscopic work were not means devised to overcome it4 ,objects for instance at ,c in our diagram would appear blue1 at ,d they would appear red1 whilst at ,e ,e though no single colour would predominate they would be illumined with many coloured rays1 though less strongly than at ,c or ,d4 ,this chromatic aberration1 as it is called1 depends amongst other things on the nature of the glass used in lens construction4 ,it has been found1 however1 that a combination of flint and of crown glass will overcome the difficulty4 ,in a later chapter we shall explain the difference between these two kinds of glass4 ,in practice1 a plano-concave lens of flint glass is combined with a double convex lens of crown glass and1 if the nature of the glass is satisfactory1 as also the shapes of the lenses1 there is full correction for chromatic aberration1 and objects viewed through such a lens will not appear with coloured margins4 ,there is one further trouble likely to occur in such1 or any lens4 ,we write of the rays meeting at a point4 ,in our diagrams we represent the rays by straight lines1 really they are much more complicated than they appear in a diagram4 ,it is quite easy to take a ruler and make our imaginary light rays meet at a point1 as a matter of fact1 where real lenses and real light rays are concerned1 it is very difficult1 if not impossible1 to make the latter meet at a single point4 ,one more diagram may make the matter clear4 ,illustration ,parallel rays ,a pass through our lens and1 as we know1 they should all meet at a point ,p1 the principal focus of the lens2 the majority do so1 but some meet at other points1 such as ,p4 ,in consequence of this it is difficult to obtain a clear image of an object at ,p1 and the lens is said to suffer from spherical aberration4 ,the perfect simple lens would be one fully corrected for chromatic and spherical aberration4 ,,chapter ,,iv ,,the ,,compound ,,microscope ,in our chapters1 dealing with1 the history of the ,microscope1 we attempted to trace the gradual development of the compound instrument from the simple lens2 we stated that the latter1 in a crude form1 had been known and used from very early times and that the former developed side by side with the telescope4 ,we have also said a few words in ,chapter ,,iii4 concerning light for the reason that the microscope can be better understood and used more efficiently when we are acquainted with the phenomena due to light4 ,the simple lens1 sold under the name of pocket magnifier1 in its cheapest form consists of a double convex lens1 that is to say1 a lens with two outwardly curved surfaces4 ,better quality pocket magnifiers consist of two or more lenses1 which may be either double convex2 plano-convex1 i4e41 with one surface perfectly flat and the other outwardly curved1 or they may be constructed of a combination of double convex and plano-concave lenses1 such as were described on p4 4 ,the object of both the simple and compound microscope is to make objects appear larger than they do to the naked eye4 ,when we buy our pocket lens we shall find that these little instruments are constructed to give different degrees of enlargement1 some make objects appear five times larger than they do to the naked eye1 some ten1 some fifteen and some twenty times larger4 ,twenty times is about the limit of magnification for the ordinary pocket lens4 ,if we are observant we shall notice something else--the greater the magnification the nearer we must hold the lens to our object4 ,within certain limits1 this is not a very serious matter1 but a point is reached where we must hold our lens so near to the object that we cannot see it1 and that is why we cannot obtain very great enlargement with a pocket lens4 ,despite this fact1 as we read in our opening chapter1 some very wonderful discoveries have been made with these simple microscopes4 ,now we wish to show how a compound microscope works and1 having done so1 to explain the uses of its various parts4 ,we shall consider the lenses of the instrument to be double convex2 we do this for the sake of simplicity4 ,even in the cheapest compound microscopes of to-day simple convex lenses are never used1 for the reason we explained in our last chapter4 ,to understand the course of the light rays passing through our microscope1 however1 we may look upon the lenses as being merely double convex4 ,let us try a simple experiment first of all4 ,for the purpose we require two double convex lenses1 one capable of magnifying more than the other1 a sheet of paper and a candle4 ,we must darken the room in which we make the experiment and1 having lighted the candle1 we may proceed to make a compound microscope1 for that is really what we are about to do4 ,taking the lens which gives the greatest magnification1 we look through it till we can see a clearly defined image of the lighted candle1 then we fix the lens at that spot1 so that1 during the rest of our experiment1 the candle and lens remain at the same distance from one another4 ,now we put the piece of paper as nearly as we can in the position of our eye1 moving it nearer or further from the lens till we have a perfectly clear image of the candle thrown upon it4 ,the first thing to strike us is that the image is upside down2 it is known as a real1 inverted image4 ,real because it can be thrown upon a screen and inverted--well because it is upside down4 ,there are some images1 as we shall learn in a moment1 which can be seen but which cannot be thrown upon a screen3 they are called virtual images4 ,having fixed our sheet of paper in position1 we take our second lens1 focus it sharply upon the back of the sheet of paper1 being careful to keep the centres of the two lenses as far as possible in a straight line with one another4 ,having obtained a sharp image we remove the paper and gradually advance our second lens towards the first4 ,we soon reach a point where we have a very much larger image of the candle than the first lens gave us2 we must fix our second lens at this point for we now have a compound microscope1 a very crude one certainly and without the trimmings which make the microscope so useful4 ,before we proceed to explain what has happened to the light rays we must take our paper screen once more and place it as near as possible to the spot where our eye was situated when we saw the second image4 ,we shall find that1 however much we may move our screen to or from the second lens we can never manage to obtain an image upon it for the reason that this second image is virtual1 but unlike the first image it is not inverted4 ,illustration ,one or two diagrams will help to explain our experiment and1 instead of the lighted candle1 we will suppose that our object is an arrow--it is easier to draw and serves just as well4 ,the magnification of the object by our first lens may be represented by the diagram below1 where ,,aa is the lens1 ,,cd the object and ,d,c its image4 ,the arrow ,c,d shows the point at which we placed our screen1 and as our diagram shows1 the image is magnified and inverted4 ,our second lens1 we remember1 was focussed on the back of the paper1 placed at ,c,d2 for practical purposes we may ignore the thickness of the paper and say that it was focussed on the image ,c,d4 ,had we left it at that1 the further course of the rays through the second lens would be represented by a replica of the diagram we have just given4 ,but1 in our experiment1 we moved the second lens nearer and nearer to ,c,d till we obtained a clear much magnified erect image of ,c,d1 let us call this second image ,c,d1 and represent the course of the light rays by a diagram4 ,illustration ,we may well ask1 why did the lens ,,aa1 our first lens1 form a real image whilst the second lens ,,bb1 which is precisely similar to ,,aa1 except that its magnifying power is not so great1 form a virtual image8 ,the formation of a real or a virtual image is nothing to do with magnification1 so we repeat--why do two similar lenses form different kinds of images8 ,let us refresh our memories with the remarks concerning the principal focus of lenses in the last chapter1 then we may try another experiment4 ,the principle focus of a double convex lens1 we remember1 is the point to which parallel rays of light converge1 after passing through the lens4 ,if now our object is further away from the lens than its principal focus1 a state of affairs that existed in the case of our lens ,,aa and the object ,,cd1 we obtain a magnified1 real but inverted image2 if1 on the other hand1 using the same lens if we wish1 the object is nearer to the lens than its principal focus1 we obtain a magnified virtual and erect image4 ,the form of image then depends on the relative positions of lens and object and not on the magnifying powers of the former4 ,after this digression1 we will see what happens when we combine the diagram showing the real1 inverted image1 formed by the lens ,,aa with the virtual erect image1 formed by the lens ,,bb4 ,in reality we will draw a diagram showing the path of the light rays through our compound microscope4 ,illustration ,we have used the same lettering as in our previous diagrams and we see that1 also as before1 a real1 inverted image ,c,d of the object ,,cd is formed by the lens ,,aa and a virtual1 erect image ,c,d of the image ,c,d is formed by the lens ,,bb1 the object ,,cd being further from the lens ,,aa than its principal focus and the image ,c,d being nearer to the lens ,,bb than its principal focus4 ,one very important point we must notice before we leave the diagram4 ,we have mentioned several times that the image formed by ,,bb is erect and so it is1 but it is an erect image of an already inverted image1 so that the final image of ,,cd1 as seen by the eye ,e is inverted4 ,the fact that objects viewed through the microscope appear upside down is puzzling at first4 ,to all intents our two double convex lenses represent a compound microscope2 actually1 they should be fixed at either end of a tube1 blackened on the inside4 ,the lens ,,aa1 nearest to the object1 would then be known as the objective and the lens ,,bb nearest to the observer's eye would be known as the ocular or1 more commonly the eyepiece4 ,there are1 of course1 very many refinements1 designed to make the instrument capable of performing the most accurate work1 and needless to say these simple lenses would neither give very great magnification nor any clear images4 ,let us describe a more refined compound microscope than the one we constructed in our darkened room4 ,the optical parts1 that is to say the lenses1 are the most important parts of every microscope1 upon their qualities depend the degree of efficiency of the instrument2 the metal portions1 known collectively as the stand1 contribute to the easier1 smoother working of the microscope4 ,illustration3 ,by the courtesy of ,messrs4 ,f4 ,davidson ,co4 ,,the ,,head ,,of ,a ,,dog ,,flea ,no wonder the flea is an annoying creature4 ,as the plate shows1 it is armed with knives1 lances and saws1 all designed to injure the skin of its victim4 ,the stand must claim our attention first4 ,the base of the instrument1 called the foot1 is usually either three-legged or horse-shoe shaped2 whatever its form it should be heavy1 for only thus can the microscope be steady1 and steadiness is essential in all microscopic work4 ,at the top of the foot there is a joint1 in order that all the other parts of the stand may be inclined at any angle1 from the vertical to the horizontal4 ,just above the joint is a bent arm of brass1 to the forward end of which a brass tube is affixed4 ,this tube is designed to hold the lenses1 the objective at its lower end1 the eyepiece at its upper end4 ,the tube is always blackened inside2 were this not the case1 light passing through the objective would be reflected in all directions from the sides of the tube and a clear image of the object could never be obtained4 ,the tubes of microscopes vary in length according to their country of origin2 ,english and ,american tubes are ten inches long1 those of continental make vary from a little more than six inches to rather more than seven inches in length4 ,affixed to the lower end of the bent arm of brass1 mentioned above1 is a flat metal plate1 known as the stage2 at its centre1 there is a circular hole through which rays of light pass to illuminate objects placed upon it4 ,below the stage1 at the edge nearest to the foot1 there is a metal peg1 over which fits a tube to which a mirror is attached by a moveable joint4 ,the mirror reflects light rays through the opening in the stage4 ,the tube1 holding it1 can be slipped up and down the peg under the stage1 thereby bringing it nearer to or further from the object and so altering the intensity of the reflected light1 as we shall explain in a moment4 ,owing to its moveable joint1 it is possible to swing the mirror to the right or left1 so that the reflected light rays do not pass directly through the object on the stage1 but strike it on one side or the other1 thereby giving what is known as oblique illumination4 ,the cheapest forms of compound microscopes have all the parts we have mentioned1 and focussing is carried out by sliding the tube1 with its objective and eyepiece1 up and down within its holder1 in order to bring the objective further from or nearer to the object4 ,in more expensive instruments there are further refinements1 in fact1 on some of the very costly present-day instruments1 there are so many appendages and appurtenances that it is doubtful whether some of them are not more of a hindrance than a help1 at any rate they increase the possibility of trouble by their liability to get out of order4 ,such microscopes are only of use to very expert workers2 there are1 however1 a good many additional features to be found on quite moderate-priced instruments1 features which are a great help to the microscopist4 ,it is obvious that we cannot attain any degree of accuracy in focussing1 especially with high magnifications1 when we must perforce raise or lower the tube by hand4 ,to obviate this difficulty1 most microscopes are provided with mechanism known as a coarse adjustment2 it consists of milled screws at either end of a metal rod2 in the centre of the rod there is a little cog-wheel which engages with a row of notches on the tube4 ,by turning the milled screws slightly in either direction1 we can impart a considerable upward or downward movement to the tube carrying the objective and focussing at once becomes a more simple matter4 ,the coarse adjustment is only useful for examining objects with a low magnification2 if we use it when objects are being highly magnified we run the risk of screwing our objective down upon our object1 to the certain destruction of the latter and the probable injury of the former4 ,to obviate such a catastrophe1 most of the better class microscopes are also provided with a fine adjustment4 ,by means of this adjustment1 which externally takes the form of a single milled screw1 a considerable turn of the screw in either direction only imparts a very slight upward or downward movement to the microscope tube4 ,in the best instruments1 movements of as little as one hundredth part of a millimetre may be imparted to the tube by the fine adjustment and1 seeing that there are about twenty-five and a half millimetres to the inch1 it is obvious that a good fine adjustment is very delicate and1 being so1 must be treated with care4 ,the fine adjustment is used to supplement coarse adjustment in the final focussing1 when using high magnifications4 ,a few words may be devoted to the mirror1 for on its intelligent use much depends4 ,usually we shall find that it is plano-concave1 that is to say1 flat on one side and hollowed out on the other4 ,the use of the mirror1 as we have mentioned already1 is to reflect rays of light through the opening of the stage on to the object we desire to examine4 ,both mirrors will reflect parallel rays of light to a point1 just as a double convex lens will so direct them from their course that they meet at a point4 ,the concave mirror gives the more powerful illumination1 because it reflects more light rays than a flat mirror of the same diameter4 ,we have mentioned that1 to obtain full advantage from the mirror it should be capable of movement to and from the stage4 ,when we desire strong illumination we arrange the mirror so that its reflected rays meet at a point coinciding with our object4 ,should less intense illumination be required1 we slide the mirror nearer to the stage1 and of course nearer to our object1 so that the reflected rays meet at a point above the object4 ,illustration ,the two diagrams1 given below1 show the path of the rays of light1 where ,o is the object1 and a trial with our microscope will soon show which position gives the more powerful illumination4 ,for high-power work1 such as bacteriology or even the examination of sections of plants1 etc41 even the best concave mirror will not give a sufficiently powerful illumination2 accordingly an instrument1 known as the condenser1 is fixed below the stage1 between the mirror and the object4 ,the condenser1 as its name implies1 condenses the rays of light reflected to it by the mirror4 ,it consists of a series of lenses so arranged that they will throw a very powerful cone of light4 ,provision is made for focussing the rays from the condenser on to the object4 ,sometimes1 for special forms of illumination1 it is necessary to cut off some of the rays of light passing through the condenser4 ,it may be that we desire to dispense with the outer rays of the cone of light or1 when delicate details are being studied1 we may wish to impede the central rays4 ,in either case diaphragms1 popularly called 8stops0 are used4 ,our diagrams show ,a the outer rays of a cone of light cut off and ,b the central rays similarly treated4 ,illustration ,in old pattern microscopes and in many instruments not provided with condensers1 the diaphragm used for the purpose of cutting off the outer rays of the cone of light1 consists of a blackened circular metal plate1 perforated with a number of different sized circular holes4 ,this plate is fixed below the stage in such a manner that1 as it is revolved1 holes of various diameters are brought one by one within the cone of light4 ,it need hardy be remarked that the smaller the hole in the diaphragm the more light is cut off and the less reaches the object4 ,in more modern instruments and in practically all which are fitted with a condenser1 an ,iris diaphragm is fitted4 ,a diaphragm of this nature consists of a number of thin1 blackened1 metal leaves1 fastened to a metal ring in such a manner that1 when the ring is revolved1 the leaves close together1 making the opening in the centre smaller and smaller4 ,the ,iris diaphragm has many advantages over the old perforated metal plate4 ,at will1 we can have any opening from full to the merest pin-point or we can cut off the light rays altogether1 should we wish to do so2 we are not confined to a definite number of stops4 ,as we cut off these outer rays of light we shall find that1 up to a certain point1 though the illumination becomes less and less the object becomes more and more clear1 or1 to use the correct expression1 its definition is improved4 ,when it is necessary to cut off some of the central rays of the light cone1 either a circle of glass with an opaque centre is dropped into a metal holder below the stage1 or a circular metal plate1 held in the centre of a metal ring by three arms1 is used in the same manner4 ,the effect of cutting off the central rays of the light cone is1 of course1 to reduce the illumination and to show up delicate detail to advantage4 ,no direct rays of light reach the objective1 such as do pass into the microscope are all diffused from the edges of the object4 ,we have already mentioned that the optical parts of the compound microscope are of greater importance than what may be termed the mechanical portions and the objectives are more important than the eyepieces4 ,better results can always be obtained with a good1 high-power objective and a low-power eyepiece1 than with an inferior objective and a good quality eyepiece4 ,the merits of the eyepiece1 however great1 will not be adequate compensation for the failings of the objective4 ,modern objectives are composed of several lenses and of a combination of flint and crown glass1 as we explained in our last chapter4 ,they are so designed that they can be screwed into the lower part of the microscope tube4 ,the focal length of each objective is1 or should be1 marked upon it2 as a general rule1 however1 it may be taken that the smaller the lower lens1 the shorter its focal length and therefore the greater its magnifying power4 ,the form of eyepiece most usually met with is known as ,huyghen's4 ,it consists of two plano-convex lenses1 with their flat or plane surfaces directed away from the objective4 ,the smaller of the two lenses is situated nearer to the eye of the observer and is known as the eyeglass2 its function is to magnify the image formed by the objective4 ,the larger1 lower lens is known as the field or collecting glass2 it renders the image clearer though1 in so doing1 it reduces the magnification of the eyeglass4 ,in instruments provided with more than one eyepiece we shall wish to know which gives the greater magnification2 this is or should be marked upon the metal rim surrounding the eyeglass but1 in general1 it may be stated that the shorter the eyepiece the greater its magnification4 ,we repeat again1 increase your magnification always1 when possible1 by using higher power objectives rather than eyepieces with greater magnifying powers4 ,sometimes it is necessary to use a greater magnification than our most powerful objective will give us2 then we must fit our most powerful eyepiece and draw out the upper part of the microscope tube--in the best instruments they are made to pull out1 after the manner of the telescope4 ,the effect of so doing will be to increase the magnification considerably but1 at the same time1 the definition or clearness is seriously impaired4 ,for the examination of practically all our microscopic objects we require a number of slides1 little glass slips of good1 thin1 clear glass4 ,they may be used over and over again unless we make permanent preparations1 but we are hardly likely to do so in our early days4 ,the slides are held in place on the microscope stage1 either by a pair of clips attached thereto or by resting against a bar running across the stage4 ,we may here remark that it is essential always to keep one's microscope slides absolutely clean4 ,dirty slides denote the careless worker2 moreover1 dirt when magnified is misleading4 ,objects which are being examined in water or any other liquid should be covered with a cover-slip1 an exceedingly thin circle or square of glass4 ,the cover-slip is as much a protection for the objective as for the object and its cleanliness also1 is all important4 ,we have not mentioned any refinements such as the mechanical stage1 by means of which slides on the stage may be rotated1 moved to the front and to the back of the stage or from side to side4 ,we have omitted these because they are not essential even for the very best work2 they lend additional comfort to the use of the microscope but1 again1 they are not essential4 ,the microscopist who requires such luxuries may learn about them in the larger text-books on the microscope4 ,,chapter ,v ,,animal ,,life ,,in ,,the ,,ponds ,,and ,,streams ,the enthusiastic microscopist will probably never lack material for his instrument1 whatever branch of microscopical work he may decide to make his own4 ,to the student of ,pond ,life1 either animal or vegetable1 there is granted a never-ending store of beautiful and interesting objects4 ,because one pond has been thoroughly searched and all that it can offer has been carefully examined1 we must not conclude that no other pond will be worth our attention4 ,though indeed many little animals occur over and over again in practically every pond1 there are other equally interesting animals which only occur in certain localities and for these we must keep a sharp look-out4 ,the apparatus needed for the collection of the denizens of ponds and streams1 need consist of no more than a net with a very fine mesh and a jar in which to bring our captures home2 for1 of course1 animals which dwell in water need not be dried on the journey home4 ,various useful accessories for the student of pond life are sold at very reasonable rates by most scientific instrument makers4 ,we shall find many representatives of the animal world in our pond and exceedingly interesting most of them will prove4 ,from the mud we may obtain the 8protean animalcule10 known to scientists as ,amba ,proteus1 the most lowly of all animals4 ,though this creature is plentiful and just visible to the naked eye1 he is not easy to separate from his surroundings4 ,he is almost colourless and therefore paler than the mud4 ,having secured him on the end of a glass rod1 let us examine him in a drop of water on a slide4 ,at first he will remain motionless1 as a protest against being disturbed2 we shall not have to wait long1 however1 for soon one part of his body will be seen to protrude and then grow larger and larger till it forms a false foot2 other parts may follow suit1 till he is more elongate than oval1 and he moves in the direction of his false foot with a curious gliding motion4 ,his pace is not great and has been calculated at a twenty-fifth of an inch in an hour4 ,really the 8protean animalcule0 is little more than an animated drop of jelly1 a fact we can substantiate by watching him feed4 ,his food consists of minute water plants such as diatoms1 and when one of these plants comes within his line of march he simply surrounds it with his false feet and1 as it were1 flows around it4 ,when he has digested all he can he flows away from the undigested portions2 he has no mouth or any of the organs usually associated with animal anatomy4 ,while hunting for our ,amba1 it is highly probable that a very active little slipper-shaped organism may have forced himself upon our attention4 ,from his shape he has earned the popular name of the slipper animalcule4 ,he is rather more highly organised than the ,amba for he possesses a mouth1 as we shall see when we are able to examine him4 ,so rapidly does he swim1 however1 that something must be done to curb his activity2 he may either be killed with a drop of weak acid or we may put a little tuft of cotton wool on our drop of water and a coverslip lightly over that4 ,the threads of cotton wool will form a network1 in the meshes of which the active little animalcule will be confined4 ,careful observation will show that he is1 like a slipper1 more pointed at one end than at the other2 that there is a funnel-shaped orifice1 his mouth1 at one side of his body2 and that he is covered with little threads which lash the water with rhythmic movement and propel him with considerable rapidity4 ,these little threads also send currents of water to his mouth1 and in the water is his food4 ,having examined these two free swimming denizens of the pond1 we may advantageously turn our attention to some of the weeds growing therein4 ,careful examination with our pocket lens will almost certainly reveal a number of minute living creatures attached to the submerged stems and leaves4 ,it is impossible to describe all the interesting creatures we might find3 we must content ourselves with two1 because they are common inhabitants of many ponds4 ,one interesting little creature we are almost certain to find1 the ,hydra4 ,he may be green or he may be brown but in structure he will remind us of a small sea anemone4 ,when we put him under the microscope he has the appearance of a mass of jelly attached to the water plant on which we found him4 ,he will soon open himself out1 however1 and we shall see that his free end is provided with a number of tentacles2 these he waves about in the water to draw small swimming creatures to his mouth which is situated in the centre of the group of tentacles4 ,any luckless creature1 coming within reach of the ,hydra1 is at once stung with one of the barb-shaped stings which stud his tentacles and then passed to his mouth4 ,the ,hydra is wonderfully tenacious of life2 it is said that he has been turned inside out1 like a glove finger1 without suffering any inconvenience4 ,probably the specimen we are examining will have a swelling on the side of its body1 which might be mistaken for the result of some injury2 it is nothing of the kind2 it is merely a bud which will grow into a young ,hydra and1 when old enough1 become detached from its parent and float away to another plant4 ,under a fairly high magnification1 we shall almost certainly see something gliding rapidly over the body of the ,hydra2 its movements are too quick to allow of careful examination2 the creature which is almost as elusive as the slipper animalcule is a parasite of the ,hydra4 ,not quite so common as our last object but still common enough to be mentioned here is the beautiful 8bell animalcule40 ,like the ,hydra1 this creature1 except in its very young stages1 remains affixed to a water plant4 ,in shape the 8bell animalcule0 resembles a wineglass on a long delicate stem2 round the part corresponding to the rim of the glass1 there is a fringe of the hair-like1 water-lashing structures with which so many of these lowly creatures are provided1 and these structures also surround the entrance to the funnel-shaped mouth4 ,when undisturbed1 the bell animalcule has its slender stalk fully extended and its little threads lash the water vigorously1 causing currents1 containing food material1 to travel towards its mouth4 ,a sharp tap on the microscope slide will cause the creature to contract1 the threads cease their lashing and the stalk contracts spirally1 so that the body of the animalcule is drawn close to the object to which it is attached4 ,by degrees the spiral uncoils and the little threads resume their lashing4 ,sometimes1 as we examine our bell animalcule1 we may be fortunate enough to see it splitting into two parts to form two separate individuals4 ,this curious process should be watched carefully4 ,the upper part of the bell splits first and1 by degrees the whole bell divides into two equal parts so that we have a pair of bells on a single stalk4 ,the next stage consists of the formation of a ring of whip-like structures round the base of one of the bells2 both bells1 by the way1 have the circlet of whips round their upper edges4 ,soon after these additional little whips are formed1 the owner of them breaks away from the stalk and swims about in the water for a time1 finally coming to rest on a suitable water weed4 ,then the lower ring of whips has served its purpose and in its place a long stalk grows2 from this time forward the new bell animalcule will never move from the position it has chosen4 ,this form of increase1 this simple splitting takes place over and over again but by degrees the little animal appears to become exhausted and the process slows down or stops4 ,the partially exhausted ,vorticella may gain increased vitality by fusion with another individual and this process also we may have the luck to see though it is less frequent than the simple splitting4 ,sometimes a bell may be observed to divide1 not into halves1 but into two unequal parts4 ,the smaller of these parts may divide again into from two to eight parts1 each one of which1 having developed a fringe of little whips1 swims off on its own account4 ,these little barrel-shaped swimming forms1 instead of settling down and forming stalked bells1 seek an exhausted creature1 fuse with it near the base of its bell and finally become absorbed by it4 ,the result of this fusion is that the bell animalcule takes on a new lease of life and once more begins to divide actively4 ,in our search for specimens for our microscope we may come across a very common pond dweller1 closely related to the bell animalcule1 known by the name of ,carchesium ,spectabile4 ,we cannot fail to recognise its family likeness to the form we have already studied1 for it consists of a large number of stalked bells growing on a single parent stem4 ,it is really a little colony of bells4 ,when one of the young individuals of ,carchesium settles down in the spot it has selected for its dwelling-place1 it grows a stalk just as ,vorticella did1 and it divides later into two individuals4 ,now in ,vorticella only the bell divides1 in ,carchesium part of the stalk divides also and1 instead of swimming away to find a new home it remains attached to the parent stalk4 ,when this has happened several times a goodly colony is formed4 ,there are few fresh-water animals more commonplace and apparently uninteresting when observed casually than the pond sponge and the river sponge4 ,yet1 if we take either of them home and examine them with the aid of our microscope1 we shall be delighted with our specimens4 ,in reality they are of absorbing interest and1 at certain times of the year we may easily obtain young sponges1 and capital objects they make for the microscope4 ,illustration3 ,photos by ,flatters ,garnett #a4 ,,starch ,,grains ,,of ,,potato ,starch is largely used as an adulterant of various foods4 ,the ,potato starch grain resembles a miniature oyster shell4 #b4 ,,phosphorescence ,,animalculae ,these minute animals1 occurring in millions1 render sea water beautifully phosphorescent4 #c4 ,,proteus ,,animalcule ,the lowliest of all animals4 ,it is a jelly-like animal which changes its shape from hour to hour4 #d4 ,,cyclops ,a common one-eyed water animal4 ,the female1 illustrated1 carries her eggs in a pair of relatively large bladder-like sacs4 ,before we describe our two specimens let us try to explain what manner of creature a sponge really is4 ,if we examine any bath sponge1 we notice that it is perforated with many small holes and some larger ones4 ,some sponges show this better than others4 ,the small holes are pores1 the large ones mouths1 but1 as we shall see in a moment we must not run away with the idea that they in any way resemble our familiar idea of a mouth4 ,these large holes are called oscula by scientists1 but we wish to avoid scientific words as much as possible4 ,the simplest sponge of all1 consists of a little bag1 which remains affixed by its base to a seaweed4 ,all over its sides there are many pores and at its tip there is a single osculum2 it is known as the ,purse ,sponge and is common round our coasts4 ,the inside of the purse sponge is lined with cells1 each one of which is tipped with a little whip which waves about unceasingly4 ,the waving of the whip causes water to flow through all the pores into the hollow bag and out again by way of the osculum4 ,although most sponges1 including our fresh-water forms1 are much more complicated than the purse sponge1 the same thing happens in them all1 water is drawn in by way of the pores and forced out by way of the oscula4 ,the best place to seek for the fresh water sponges is on the under sides of floating wood1 broken tree branches and the like4 ,their appearance depends upon whether they have been growing in a well-lighted spot or in darkness2 they contain chlorophyl as do the higher plants1 and sponges grown in the light are green1 those which the light has not reached are buff-coloured or corn-yellow4 ,the pond sponge is brighter green than its river frequenting relative and is a coarser creature altogether4 ,it often forms little finger-like outgrowths1 whereas the river sponge is more leaflike4 ,if we examine one of these sponges in a watch glass of water to which we have added a very little carmine powder1 we can easily see the water currents entering the pores and coming from the oscula4 ,towards autumn1 if we open a river sponge we shall see little yellow bodies about the size of a pin's head2 they are the buds from which the young sponges arise4 ,one of these must be removed very carefully and placed in a watch glass of water2 if our specimen be placed in the sun1 we shall not have many days to wait before we find that it has given rise to an active transparent little creature1 to a young sponge in fact4 ,by repeating our experiment with carmine1 by the aid of the microscope1 we can see the water currents passing through its body4 ,wherever we collect our pond water we are certain to find some of the wheel animalcul or rotifers4 ,there are such a number of different kinds that we might describe several1 and yet not mention the one that any of our readers had happened upon4 ,they may be recognised1 because they are always so transparent that all their internal organs may be plainly seen and they always have two or more discs or lobes1 at their forward end1 fringed with fine whip-like threads4 ,these little threads are constantly in motion1 so that they appear like little revolving wheels hence the name1 wheel animalcule4 ,nearly all these creatures have a sucker or false foot at their tail end by means of which they attach themselves to some support or they may swim freely in the water4 ,the study of rotifers has been the life-work of some scientists and they will afford any microscopist1 who is interested in them with abundant occupation4 ,amongst the water weeds we shall probably find another small but striking creature1 known as the sun animalcule1 ,actinophrys ,sol4 ,why exactly it is called the sun animalcule we cannot say1 probably it has earned its title from the fact that it resembles the conventional idea of the sun1 with light rays radiating all round its circumference4 ,the creature is whitish-grey in colour1 spherical in shape and just visible to the naked eye4 ,all over the surface of its body there are a number of apparently empty spaces1 known as vacuoles--they probably account for its peculiar colour4 ,everywhere1 it is studded with long1 slender-pointed rod-like outgrowths4 ,but rarely1 the sun animalcule exhibits any movement and for long periods the only signs that it is living occur at feeding time4 ,its food consists of water animals and plants1 of varying size4 ,when a small animal comes into contact with one of the pointed rods1 which radiate from the animalcule1 it appears to be held there in some unaccountable manner and1 after a pause1 it begins a fateful journey by sliding down the rod to the spherical body of its captor4 ,then it is passed into one of the vacuoles and digestion very soon takes place4 ,that it does not do so immediately is shown by the fact that the wheels of a wheel animalcule1 which has been passed to the vacuole of our subject1 continue their movements for a considerable period4 ,when larger animal food is partaken of1 a different method is pursued by the sun animalcule4 ,a water-flea1 for instance1 coming into contact with one of the rods will struggle violently in its efforts to escape4 ,then the sun animalcule shows real signs of life1 for some of the other rods bend over and hold the captive so that it1 eventually1 is passed to a vacuole4 ,in our chapter on agriculture we mention a peculiar flat worm known as the liver fluke4 ,this unpleasant creature has one or two relatives who make their home in ponds and1 though they are not more beautiful than the liver fluke to look upon1 they are quite harmless4 ,one of these flat worms is about #c_/d-;inch long and not unlike an indian club in shape4 ,it moves about1 with some speed either by the aid of a sucker on its head or by a curious gliding movement4 ,the other pond-frequenting flatworm is more like the liver fluke1 its leaflike oval body1 about #a_/b-;inch long1 is pointed fore and aft4 ,it is a common sight to see it gliding here and there in search of still smaller animals off which it may make a meal4 ,the sea mat and bird's head1 two common animal colonies of the sea-shore1 possess pond-dwelling relatives of the greatest interest to the microscopist4 ,like the seaside forms they dwell in colonies4 ,one of the commonest is known as ,lophopus ,crystallinus and it may be found attached to duckweed1 the curious little plant whose tiny leaves float upon the surface of the water4 ,lophopus1 when at rest1 resembles a little piece of jelly4 ,if we are patient and watch it under our microscope we shall see it expand1 sending forth a number of stalks1 each one tipped with a horse-shoe shaped feathery tentacle4 ,each of these tentacles belongs to a separate animal which with its fellows forms a colony4 ,not so interesting are the branched1 threadlike colonies of ,plumatella ,repens which may be sought upon the leaves of water plants4 ,our ponds can furnish no more extraordinary object for our microscope than a colony of ,cristatella ,mucedo2 it is curious in appearance and still more curious from the fact that though a colony of animals it acts like a single individual in crawling over the weeds and stones in shallow1 sun-kissed water4 ,the ,cristatella colony is jelly-like and greenish in colour1 in length it may grow to a couple of inches4 ,its under surface is flat1 whilst from its upper1 convex surface the little animals forming the colony wave their brush-like tentacles in the water4 ,in searching the various pond weeds for specimens we are sure to meet with various jelly-like masses2 these must always be examined carefully4 ,they may be the egg-masses of interesting water creatures2 various water-snails1 for instance1 protect their eggs with a jelly-like covering4 ,if we meet with any large fresh-water mussels1 sometimes called swan mussels1 we shall probably find the fleshy parts of the molluscs swarming with minute creatures1 which we may conclude are parasites4 ,mussels1 like nearly all living creatures1 have their parasites it is true1 but what we have discovered will almost certainly prove to be young mussels4 ,we must examine them under the microscope to make sure4 ,then we shall see1 if young mussels they be1 very minute and very thin-shelled little creatures2 the edges of their shells are armed with teeth and are quite unlike the highly polished and smooth shells of the parent mussel4 ,we shall also see a long thread issuing from the animal within the shell4 ,if we are examining the young mussel in water we shall notice that it is constantly snapping its two shells together4 ,had we left these young mussels undisturbed1 a very curious life they would have led4 ,they would have remained attached to their parent for some little time probably1 or some of them might have fallen to the muddy bed of the pond4 ,their behaviour in either case would be the same4 ,the long threads that we have already examined would have floated in the water and1 directly they were touched by a passing fish1 the little shells would begin to snap violently4 ,the lucky ones would not snap in vain for they would close upon the fin or tail of the fish and then their snapping would cease4 ,like the bulldog1 these little mussels may take a long time in getting hold but when once they have managed to fasten their teeth into anything it is well-nigh impossible to make them let go4 ,usually they never let go1 but are carried away by the fish4 ,in most cases1 the irritation they set up in the flesh of their new-found foster parent causes a swelling to occur with the result that the little mussels are engulfed4 ,within the flesh of the fish they go through a series of changes2 they lose their teeth and their tell-tale thread1 they become in fact miniatures of the adult mussels1 then they manage to escape from the fish1 settle down in the mud and fend for themselves4 ,the crabs and lobsters which we know so well have fresh water relatives in nearly every pond4 ,many of the creatures we have examined have needed careful search to discover their whereabouts2 not so the fresh water crustacea1 as they are called4 ,their activity1 their curious movements in the water compel attention4 ,the fresh water shrimp is a curious little creature1 sometimes he paddles his three pairs of hind legs and sometimes he jerks his body in a ludicrous manner1 in either case he manages to propel himself rapidly through the water4 ,he is about half an inch long1 brown in colour and with a curved body not unlike a shrimp4 ,if we examine him under the microscope we notice that his front legs are bent forwards1 whilst his hind legs are bent backwards4 ,the male water flea is much larger than the female1 a fact which probably accounts for the fact that these little animals often carry their wives about with them by seizing them with their fore legs4 ,the water louse we may also encounter1 he is not nearly so interesting as the fresh water shrimp4 ,he is closely related to the wood louse which we all know1 and has a similar flattened body4 ,very much smaller though even more interesting is the common water flea4 ,by day these animals retire to the mud at the bottom of the pond but1 morning and evening1 they swim actively with a curious jerky motion4 ,we must examine our specimen carefully for he is of more than ordinary interest4 ,we cannot fail to observe how transparent he is1 so much so that all his internal organs can be plainly seen1 but let us deal with his exterior first of all4 ,his large eyes are plainly visible1 but his most conspicuous feature is the pair of large branched feelers1 by means of which he swims4 ,if we examine several specimens1 one or more is certain to be a female1 then we may probably observe an egg in process of formation in the brood pouch1 a large1 elongated cavity1 just below the back of the animal4 ,immediately above the brood pouch1 the heart is situated and1 if we can induce its owner to keep still for a moment or two1 the heart-beats may be plainly seen4 ,not unlike the water flea as it swims about in the water of our collecting jar is the curious1 transparent little creature known as ,cypris4 ,although so transparent its body is contained in a pair of shells1 very similar to those of the mussel2 a fact which formerly led to its being classed with the shell-fish4 ,we may well examine this little fellow under the microscope for much of his structure may be made out through his shell4 ,his very conspicuous eye is sure to attract our attention2 he possesses but a single eye and seems to make up for the lack of a second by having a very large one4 ,two pairs of feelers project beyond the shell in front4 ,of his two pairs of legs the foremost1 or at least their tips1 hang down below the shell1 but the last pair1 as we can see through the shell1 are turned upwards4 ,at the hinder end of the body1 there are two long bristles1 they may best be seen when ,cypris is swimming4 ,of what use exactly these bristles may be to their owner is not definitely known1 but it is thought that they are of service in keeping his shell clean4 ,another active little animal1 quite as common as the water flea1 is sure to attract our attention4 ,it is no larger than the water flea but much more elongated2 some specimens are bigger than others1 and the bigger ones are the females4 ,its name is ,cyclops and1 though so common1 it has no popular name4 ,cyclops is so named on account of the fact that it possesses but a single eye2 it is1 however1 rather an interesting creature in other respects1 so we will study it more closely4 ,looking down upon the creature1 we see that the front part of its body is composed of an undivided shield1 behind which there are four plates and behind these again there are in the male five and in the female four segments or rings1 at the extreme tip there is a forked tail1 each fork being furnished with a number of bristles4 ,on the head are two pairs of organs1 one pair long the other pair short and1 if we observe ,cyclops in the act of swimming1 we shall see that the long pair of organs play the chief part4 ,in the centre of the front of the head there is a black or red patch--the eye4 ,very frequently we may meet with a specimen carrying a relatively large bladder-like body on each side of its abdomen4 ,these bladders which are each about one-third as long as the creature which carries them1 are egg-sacs4 ,if we are able to secure one or two specimens with egg-sacs attached1 we can study the young ,cyclops without much difficulty4 ,take a small glass tube--a test-tube as used by chemists will serve admirably--partly fill it with pond water and add a little water weed1 then introduce the egg-bearing females and place in the light4 ,we must watch the tube from day to day1 and before long it will be evident that the young ones have arrived in the world1 for we shall have no difficulty in seeing dozens of little white specks swimming about in the water and settling on the sides of the tube4 ,we must remove one carefully on the end of a glass rod or on a paint brush and examine it in a drop of water under the microscope4 ,this young creature is totally unlike its parent1 it is oval and possesses three pairs of stiff bristles1 of which the first pair are simple and the other two pairs are branched4 ,although the bristles are used solely for swimming at this stage1 it may be of interest to mention that in the adult ,cyclops they become transformed into jaws and the two pairs of organs we have already examined4 ,at the front end of the oval body we can closely distinguish the single eye1 which persists throughout life4 ,,chapter ,,vi ,,plant ,,life ,,in ,,ponds ,,and ,,streams ,in this chapter we shall confine ourselves to the true water-dwelling plants1 as distinct from those1 such as the water lilies1 which though never found growing on dry land1 appear undecided whether they will be water plants or land plants4 ,looking at the matter from a more scientific point of view1 all our pond plants will be much lower in the scale of development than the water lilies and other flowering plants4 ,pond life is rich in subjects for the microscopist4 ,any stagnant pool may contain organisms which will delight the naturalist who has always depended upon his unaided vision4 ,curiously enough1 amongst the most wonderful of all these pond-dwelling plants are the ,diatoms1 which consist of but a single cell4 ,they are so numerous1 they exist in so many different forms and in so many different situations that were we able to describe them all1 we should require the whole of a large volume1 much larger than this4 ,in colour1 ,diatoms are usually brown or brownish1 although they contain chlorophyll1 the green colouring matter of higher plants4 ,in shape they may be rod-shaped1 crescent-shaped1 circular1 wedge-shaped1 oblong or oval4 ,some float about freely in the water1 some are attached to supports by means of stalks4 ,some lead a solitary life and others dwell together in colonies4 ,one feature they have in common1 a curious flinty cell wall1 and this is their most interesting point to the microscopist4 ,this natural armour is in two parts which fit one within the other like the two halves of a ,japanese basket4 ,all manner of beautiful sculpturing marks these beautiful frustules as they are called2 in some cases they are perforated and the living matter from within passes through the pores and forms a jelly-like covering for the little plant4 ,we must make a point of collecting all the ,diatoms we can find1 for they are always interesting2 moreover1 they are easily preserved and made into permanent slides1 for the little plants may be boiled in acid to destroy their living parts and the frustules will survive the boiling undamaged4 ,one might wonder how such humble plants1 surrounded as they are with flinty walls1 could increase4 ,they frequently do so in a simple manner4 ,the living matter of which the plant is composed pushes the frustules apart and divides across the middle4 ,the result of this event is the formation of two plants1 each with a single frustule4 ,in a very short time each plant grows a new frustule1 but it is always much smaller than the one with which it started4 ,the movements of some of the free swimming1 that is to say non-attached ,diatoms1 are worthy of study4 ,the scientific name of one kind1 translated into everyday language1 means little boats1 and indeed they are well named for their beautiful aquatic manuvres rival those of any ship4 ,somewhat similar in habit to the brown ,diatoms are the green ,desmids1 but1 whereas1 the former also occur in the sea1 the latter are all confined to fresh water4 ,sometimes ,desmids are so numerous that they make the pond water as green as green-pea soup4 ,it would be as impossible to describe all these plants as was the case with the ,diatoms1 but generally they may be recognised by the fact that they are composed of two similar halves1 separated by more or less of a waist4 ,although some of the ,desmids exhibit a certain amount of movement they are not active like the ,diatoms4 ,late spring and autumn are the best seasons to hunt the ponds for our next object1 which rejoices in the name ,chlamydomonas ,angulosa1 a good example of the extraordinary fact that some of the smallest animals and plants have the longest names4 ,this little plant is interesting in itself and doubly so1 because it was for long thought to be an animal2 it is wonderfully animal-like in its movements4 ,chlamydomonas is very minute1 so we must use our highest magnification when we examine it4 ,it is an oval1 one-celled plant enclosed in a clear membrane4 ,the green colouring matter is arranged in the form of a cup1 within the hollow of which is a mass of granular living substance4 ,at the forward end of the plant1 there is a clear space and near the tip a brownish dot1 known as the eye spot2 which1 though incapable of seeing as we understand it1 is sensitive to light1 as shown by the fact that the little plant will swim towards moderately intense light and away from strong light4 ,if we stain the plant with iodine we can plainly see a pair of little whips arising from the clear portion at the forward end2 it is by the lashing of these that the plant is enabled to swim4 ,in the mud of our pond we may find a little colony of plants which might forgivably be mistaken for a collection of the individuals we have just studied4 ,each member of the colony is very much smaller than ,chlamydomonas to be sure1 but each one has the outer membrane1 the brownish eye spot and the pair of little whips4 ,on the other hand the chlorophyll fills the whole of each cell and is not arranged in the form of a cup4 ,sixteen cells form a colony1 and the whole mass is a flat plate2 the little whips move in unison and the whole colony revolves after the manner of a wheel4 ,another little colony we may encounter also1 consists likewise of sixteen cells very like the ones we have described1 but somewhat wedge-shaped instead of oval4 ,a jelly-like mantle encloses the colony and1 in outline1 it is spherical1 so that when the little whips1 which project through the mantle1 lash the water the whole colony revolves4 ,the most remarkable of these colonies of cells is known as ,volvox ,globator1 it may be recognised by its perfectly spherical shape and its characteristic movements in water4 ,volvox is about #a_/be inch in diameter1 and although to the uninitiated it appears to be a single minute plant1 in reality it is a colony of upwards of twenty thousand cells4 ,the colony may be considered as being made up of thousands upon thousands of cells1 very similar to those of ,chlamydomonas1 and each one arranged with its pair of little whips directed outwards4 ,within the ,volvox sphere we may observe a number1 usually one to eight1 of smaller spheres4 ,these are so-called daughter colonies which have arisen from the continued division of special cells4 ,they develop1 fairly rapidly1 into young ,volvox colonies1 then they burst through the cells of the parent colony1 swim out into the water and quickly grow to the size of the ,volvox from which they were formed4 ,there is another kind of ,volvox of a yellowish colour and much smaller than ,globator1 the big one is the one we must procure2 it is much more easily studied4 ,certain of the plants we shall find in our pond are so animal-like in their movements1 that the microscopist who sees them for the first time may wonder whether we are not mistaken in calling them plants4 ,we have already described the common ,chlamydomonas1 with its curious jerky method of propelling itself through the water4 ,there is1 however1 an equally common one-celled1 pond-frequenting plant which has puzzled naturalists even more1 for it certainly possesses many very animal-like characteristics4 ,its name is ,euglena ,viridis and we require our highest magnification to examine it for it does not exceed one-two hundred and fiftieth part of an inch in length4 ,usually1 ,euglena is cigar-shaped but1 as it possesses the very unplant-like characteristic of not having a firm cell wall it can change its shape to a considerable extent and it often assumes curious forms4 ,at the forward end of this minute plant there is a single whip-like thread1 by means of which it swims2 a little below the base of the whip1 there is a red eye spot4 ,elsewhere we have described how the protean animalcule feeds by flowing round its food-material1 ,euglena feeds in a similar manner1 but it also feeds after the manner of a plant4 ,when this active little plant is about to increase it either divides into two lengthways or becomes surrounded with a firm wall within which it breaks up into a number of young forms which are released later by the bursting of the wall4 ,illustration3 ,photos by ,flatters ,garnett #a4 ,,bladderwort ,a ,british water plant which entraps small animals in its bladders and digests its captives4 #b4 ,,spores ,,of ,,horse ,,tail ,these spores with their thread-like outgrowths vary in appearance according to the moisture in the air4 #c4 ,,hairs ,,on ,a ,,potato ,,leaf ,the star-shaped hairs on a potato leaf make beautiful objects for the microscope4 ,leaves of many plants are clothed with curious hairs4 #d4 ,,spirogyra ,a green thread-like water weed4 ,two threads are shown fusing together2 from each part of these fused threads a new plant will arise4 ,small wonder that scientists were in doubt concerning the true nature of ,euglena1 its non-walled cell and peculiar mode of feeding are indeed puzzling4 ,there are many similar cases amongst these lowly organisms1 in fact there are some creatures which may best be described as partly plant and partly animal4 ,those of our readers who are interested in such problems may read an excellent account given much more fully than we could give it here1 in ,professor ,f4 ,w4 ,keeble's ,plant ,animals1 one of the excellent ,cambridge ,manuals of ,science4 ,the fact is that the demarcation between plants and animals1 low in the scale of development1 is not nearly so pronounced as it is amongst the higher forms of life4 ,amongst the plants of our pond we shall find that1 like the land plants1 most of them are green1 and many of them are thread-like1 so that the task of distinguishing one from another may appear difficult4 ,examined with the naked eye1 many of them appear remarkably similar to one another2 under the microscope the differences are obvious4 ,one of the most remarkable of the commoner pond plants is known as ,oscillatoria2 it does not boast of a popular name but its scientific name is not very difficult to remember after we have witnessed its oscillations4 ,oscillatoria is a plant with particularly animal-like movements4 ,it is merely a thread1 usually green-blue in colour1 but sometimes red or violet4 ,the threads are never branched and1 except when in motion1 are straight4 ,under a moderately high magnification we can see that this thread-like plant is not composed of a single cell but that it consists of a number of cells1 placed end to end4 ,sometimes a few of these cells will break away and start life on their own account4 ,whatever interest the structure of ,oscillatoria may have for us1 we cannot help being struck with its movements1 and we must make a point of observing them4 ,the movement is peculiar and not easy to describe nor1 so far as we know1 has it ever been explained4 ,a thread will be seen to glide backwards and forwards1 becoming somewhat curved and1 at the same time1 revolving on its axis4 ,eel-like is perhaps a good description of the movement4 ,it is possible to distinguish this plant from other pond dwellers by its slimy 8feel0 which arises from the fact that each thread is enclosed in a jelly-like sheath4 ,the silk weeds1 ,cladophora ,glomerata are somewhat similar in appearance to the plant we have just described1 but they are denizens of running streams rather than of ponds4 ,they are the green thread-like plants we so often see attached by one end to rocks and stones beneath running water4 ,each plant consists of a long1 cylindrical structure composed of several cells4 ,we mention the silk weeds here1 because they are best of all plants for showing cell growth4 ,this growth takes place at or near the unattached end of the plant and is easily observed4 ,the end cell may be watched for the process4 ,its green contents will be observed to contract in the middle so that it assumes an hour-glass shape4 ,then1 where the contraction has taken place1 we can watch the formation of a wall right across the cell1 so that when the process is completed we have two cells where formerly there was one4 ,more rarely1 the contents of a cell will be observed to bulge out a side wall1 then a new wall is formed to divide it off from the main cell and thus the beginning of a branch is formed4 ,the silk weeds exhibit no movements1 except such as are imparted to them by the running water4 ,a very beautiful little pond plant is known to science as ,draparnalda ,glomerata4 ,we shall probably forget its name1 but we can never forget the plant itself when once we have been fortunate enough to see it4 ,a single row of large1 transparent cells1 containing very little green colouring matter1 forms the main part of the plant4 ,at regular intervals from these transparent cells1 there arise rings of deep green branches1 each one tipped with an extraordinarily long1 colourless hair4 ,draparnalda is indeed a plant worth looking for4 ,two common little green plants grow so near to the edges of ponds that they may well be included amongst our pond plants4 ,the simpler of the two1 known as ,vaucheria ,sessilis thrives on almost any damp soil and may even form a covering on soil in pots4 ,in structure1 ,vaucheria is very simple for it consists of a single1 frequently branched1 tubular cell4 ,the little attaching organ1 by means of which the plant fixes itself to some firm support1 is colourless1 so too is the tip of the cell where growth takes place4 ,we must examine this little plant when we come across it and we must not fail to notice that it is composed of but one cell4 ,the only time at which we can find any cross walls1 is when ,vaucheria is about to increase4 ,then the tip of the cell swells1 like a little club1 and a cross wall separates it from the rest of the plant4 ,the contents of this cell rounds itself off1 becomes fringed with innumerable little lashing whips and escapes from a pore at the tip of the cell in which it was formed4 ,this little organism swims about for a time in the water1 for ,vaucheria only increases in this manner when it is under water1 at length it comes to rest and forms a new plant4 ,closely related to ,vaucheria1 but not quite so common1 is the curious little plant known as ,botrydium ,granulatum4 ,like our previous example1 it is a one-celled plant and herein lies its interest4 ,when find a specimen growing by a pond1 we shall notice a green bladderlike portion1 not more than #a_/f inch in diameter1 which projects above the ground4 ,below ground1 if we pick the soil away carefully we may observe a number of colourless1 branched structures which do duty for roots4 ,the bladder and underground portions are hollow1 being lined in the case of the former1 with a network of chlorophyll beautiful to observe under the microscope4 ,botrydium usually increases by buds which form on the green bladder1 break away and grow into new plants4 ,should the level of the water in the pond rise1 and the little plant become submerged1 it splits up into a number of small bodies1 each provided with a minute whip-like organ1 with which they swim rapidly ashore where they develop into new plants4 ,in dry weather the plant forms a number of little cells each one surrounded by a firm cell wall4 ,when moisture comes again these little cells give rise to structures which will grow into new plants4 ,surpassing even ,drapernalda ,glomerata in point of beauty1 is the 8water-net10 ,hydrodictyon ,reticulatum1 but it is not nearly so common1 being confined to ponds in the ,south and ,midlands4 ,when full grown it hardly comes under the heading of a microscopic object1 for it may measure as much as six inches in length4 ,this remarkable pond plant consists of an open network of green filaments4 ,apart from its striking appearance the most remarkable thing about the 8water net0 is its rapid growth4 ,carpenter1 a noted microscopist says3--8,the original cells of which the net is composed measure one-two thousand five hundredth part of an inch in length but in a few hours they grow to one-twelfth of an inch or #a_/c of an inch in length4 ,we often hear people remark that they can see plants grow1 but their statements are not literally true2 in the case of the #8water net' it is actually possible to see the growth40 ,by the side of our pond we shall probably observe some masses of a bluish-green jelly-like substance4 ,it is uninteresting-looking material for the microscope1 but we must not pass it by4 ,the blue-green jelly encloses a plant called ,nostoc1 which resembles nothing so much as a necklace of beads2 this we can plainly see under a low magnification4 ,we shall observe that the plant is twisted spirally within its covering and also that most of the cells1 which we have compared to beads1 are similar to one another in size4 ,at intervals there are larger cells and as the plant increases in length they are emptied periodically1 so they are evidently used as food stores4 ,from time to time portions of the plant break away1 worm their way out of the jelly and move about1 rather after the manner of a worm4 ,eventually1 these wanderers come to rest and become surrounded with more of the blue-green jelly1 thus forming a new ,nostoc colony4 ,these plants sometimes appear1 apparently from nowhere1 on garden paths1 walls and similar situations1 during damp autumn weather4 ,on this account the plants have been called 8fallen stars40 ,their appearance is not so mysterious as it might seem for the ,nostoc colony has probably been where it is found1 all through the summer1 in a dried up1 contracted state4 ,only when rain comes1 does the jelly envelope absorb water1 swell up and assume its normal appearance4 ,the blue-green scum which floats on stagnant water is a closely related plant4 ,another plant which looks like scum on the water is known as ,spirogyra and a very beautiful object it makes for the microscope4 ,it is bright green1 without a bluish tinge1 so it need not be confused with the plant we have just mentioned4 ,there are seventy or so different kinds of ,spirogyra1 therefore our description must be the one that will apply to all4 ,the plant is thread-like and1 even in the larger kinds1 the threads are not more than one-hundredth part of an inch in diameter4 ,like ,oscillatoria the plants are not attached to any support4 ,each thread is composed of many cells1 arranged end to end2 we can distinguish the cell walls clearly1 but what will chiefly attract our attention are the beautiful bands of green colouring matter1 running spirally1 round each cell4 ,if we are fortunate1 we shall see the plant in the act of increasing2 this is not the simple operation we witnessed in the silk weeds4 ,from two threads lying parallel to one another1 we shall see swellings arise on the adjacent cell walls2 the beautiful spiral bands will begin to break up at the same time and to collect in a mass towards the centre of each cell4 ,the swellings of adjacent cells touch1 their end walls break down so that the two cells become connected1 our figure shows the fusion taking place1 then the contents of one cell passes into the adjacent cell and fuses with the contents of the latter4 ,the new cell1 which now contains not only its original contents but that from a cell in another plant1 becomes detached from the thread1 assumes an oval shape and sinks to the bottom of the pond1 where it rests awhile4 ,at a later period the cell wall bursts and a new thread of ,spirogyra develops from it4 ,when we are examining ,spirogyra we may notice some very minute brick-red1 spherical bodies adhering to the green threads4 ,these are little pond animals1 known by the name of ,vampyrella ,spirogyr4 ,this little creature passes through an interesting and easily observed series of changes4 ,its life is very uneventful1 consisting of a good meal of ,spirogyra1 a period of rest followed by an increase1 and this is repeated over and over again4 ,if we watch our little sphere through the microscope1 we may be lucky enough to see the contents divide into four parts4 ,now we must watch carefully1 for very interesting events are about to take place4 ,each of the four parts into which the contents of the sphere has split1 escapes into the water and swims about for a time2 it then becomes spherical1 but instead of having a smooth outer surface1 as it had when we first observed it1 we can see that it is now studded all over with very fine threads4 ,it then wanders along a ,spirogyra plant1 attaches itself to one of the cells1 perforates its wall and sucks out the contents4 ,this performance it repeats several times then1 evidently satiated1 it loses its threads and resumes the appearance it had when first observed and thus it rests1 till division of its contents into four parts takes place once more and the little comedy is repeated4 ,now we must tear ourselves away from our pond2 there are very many interesting objects for our microscope on the sea shore and if we delay too long here1 we shall not be able to give them the attention they deserve4 ,,chapter ,,vii ,,the ,,microscope ,,and ,,plant ,,life ,the science of botany consists of many branches and1 in most of them1 the microscope is the scientist's constant aid4 ,the study of bacteria1 really a branch of botany1 we have dealt with in another chapter1 so here we will omit these interesting though lowly plants4 ,by far the number of botanical objects for the microscope consist of sections--exceedingly thin slices of whatever portion of the plant is being examined1 cut either with a sharp razor or a special instrument called a microtome4 ,section cutting1 though not a difficult accomplishment1 requires a considerable amount of practice and cannot be learned from a book2 all our descriptions1 therefore1 will be confined to objects from the plant world which may be studied without the assistance of razor or microtome4 ,one cannot help being struck with the fact that green is the prevailing colour among plants and the reason is not far to seek4 ,if we take a cabbage leaf and carefully tear off the skin1 we shall find green spongy matter below4 ,a little of this green material may be examined under the microscope and will show us rounded green bodies composed of a substance called chlorophyll4 ,now chlorophyll is absolutely necessary to all plants1 except the fungi and to one or two parasitic plants4 ,it is necessary because1 by its aid1 plants can build up raw food material into food which will be useful to them4 ,it is not formed in darkness2 that is why a board1 a roller or any similar object left on a lawn1 causes the grass below to turn yellow2 it is the reason also why certain parts of plants1 not usually green1 turn that colour when exposed to the light4 ,chlorophyll does not always occur in round globules1 sometimes it is found in bands4 ,one of the most interesting botanical studies for the microscope is furnished by the leaf of the ,american water-weed4 ,this plant1 which was introduced into the country from ,north ,america some years ago1 has now spread far and wide and is easily obtained4 ,a leaf which is slightly yellowed with age is the best to take for the experiment4 ,it should be cut from the plant1 placed at once in a small bottle of water and kept warm for a few hours2 this may be accomplished by keeping the bottle in one's pocket4 ,after a sufficient interval1 put a drop of water in a clean slide1 put the portion of leaf in the drop of water1 cover with a coverslip and examine with a moderately high power4 ,if the experiment has been properly carried out a wonderful sight will reward us4 ,we shall see that the leaf is divided into a number of divisions called cells2 this name has been handed down from the very early days of the microscope1 because of a supposed resemblance to the cells in a bee's honey comb4 ,in each cell we shall see signs of activity1 the little round grains of chlorophyll are there1 but instead of being stationary1 as in the cabbage leaf1 they are slowly moving round the walls of each cell4 ,in reality they are carried along in the stream of living matter within the cell4 ,it is a wonderful sight and brings home to the observer very forcibly a fact which is liable to be forgotten1 that the plant is just as much a living being as an animal4 ,perhaps our experiment will not succeed at the first attempt1 then we must try again2 maybe we have been too rough in detaching the leaf or we have not kept it sufficiently warm4 ,sometimes the movement may be started by slightly warming the slide over a flame2 too much heat1 of course1 will kill the leaf4 ,we shall see this green colouring matter over and over again in our botanical studies1 in fact it is found in all manner of situations1 in leaf and stem4 ,very often its colour is hidden by sap of another colour1 as for instance in copper beech leaves or in the brown seaweeds4 ,chlorophyll dissolves in alcohol1 however1 and this affords us a ready means of detecting its presence though we cannot see its green colour4 ,if we boil any leaf1 suspected of containing chlorophyll1 in alcohol we shall obtain a solution with rather peculiar properties because1 when held up to the light it appears green1 but when light is reflected from it1 it appears reddish4 ,from the under side of the cabbage leaf whence we obtained our first specimen of chlorophyll1 we must now take another piece of skin4 ,if we perform the operation properly the skin will be colourless1 like a piece of thin parchment2 any green colour will show that we have torn off more than the skin and we must make another attempt4 ,having secured our piece of skin we place it in a drop of water on a clean slide and examine it under the microscope4 ,we first notice that the skin is divided up into a number of small areas called cells and dotted here and there amongst the cells are several oval bodies1 containing chlorophyll4 ,these oval bodies are the pores through which the leaf breathes1 amongst other things4 ,in the centre of each pore there is a hole1 at least there is if the pore is open1 for the two cells comprising the pore have the power of opening and closing4 ,it is interesting to try the same experiment with a fern leaf and to notice that there are pores1 very similar to those of the cabbage1 but that the walls bounding the cells of the leaf are irregular and that they contain chlorophyll4 ,we may try several other leaves and also the upper and lower surfaces of leaves1 then we shall soon learn that1 in leaves with distinct upper and lower surfaces1 there are far more pores on the lower than the upper surface2 leaves like those of the iris have almost the same number on each side1 and floating leaves1 like those of water lily have all their pores on the upper side4 ,there is a reason for this2 the pores are likely to become filled with dust1 being on the lower side they are protected somewhat2 flat leaves1 by their shape1 afford no protection and floating leaves must have their pores on the upper surface to obtain air4 ,there are many other interesting things we may learn about leaves1 with the help of our microscope4 ,the cabbage leaf is quite smooth1 but if we are observant we shall have noticed that sometimes each leaf appears as though it had been powdered1 it has a decided bloom4 ,the bloom does not appear on the leaf for ornament but for a purpose4 ,it is a waxy substance and it prevents the leaf from losing moisture too quickly in dry weather4 ,this is very important for the plant2 if the moisture taken up from the soil were lost in the air too quickly by the leaves1 the plants would wither and eventually die4 ,it is not all plants which can wear a protective covering when danger threatens1 most plants have either no protection or are permanently protected4 ,there is a large class of plants with folded or rolled leaves2 heather and marram grass belong to this class4 ,we must examine some of these leaves and we shall find that all the pores are on the inside of the leaf whether it be folded or rolled4 ,the reason for this is that moisture also escapes through the pores and1 when they are thus protected1 it is not carried off too quickly by drying winds4 ,many plants are protected1 as far as their leaves are concerned1 at anyrate1 by hairs4 ,they take the place of the bloom in such plants as the cabbage4 ,there are thousands of plants with hairy leaves and they will provide as many interesting objects for our microscope4 ,let us examine as many as we can for the hairy covering of each plant will be a little different to the one we examined previously4 ,there are simple hairs1 quite ordinary affairs1 forked hairs1 branched hairs1 ,t-shaped1 star-shaped and club-shaped hairs4 ,if we are clever with our microscope we shall notice that1 however complex each hair may be it is really nothing but one cell of the skin of the leaf which has assumed a peculiar shape4 ,the leaves of the nettle are armed with ordinary and stinging hairs2 the latter are worth examining and we shall notice that there is one great difference between all the other hairs we have examined and the stinging hairs of the nettle4 ,the former are of one cell only1 the latter of several cells4 ,a high magnification will show that the stinging hair of the nettle is not quite so simple as it appears at first sight4 ,there are plants whose leaves are protected by very thick skins and others whose leaves become armed with hard flinty matter1 so that they resemble stones rather than leaves4 ,if we can find some quite young seedlings we must manage to secure one or more for examination under our microscope4 ,we must take one up very carefully and wash the earth from its roots--if we pull the earth away our specimen will be ruined4 ,near the tips of the root branches we shall see something which might be mistaken for mould4 ,our microscope will show us that they belong to the root2 they are1 in fact1 root hairs4 ,we shall very likely be able to make out that1 like the leaf hairs1 each root hair is made up of a single cell4 ,the root hairs are interesting because it is through them that water is taken up by the plant from the soil4 ,in many plants a considerable space separates the root from the leaves4 ,when we have learned how to cut sections1 we can make slides for our microscope which will show us the whole course along which the water travels1 from its point of entry at a root hair to its exit at a leaf pore4 ,although we have not yet reached that stage1 it need not prevent us from seeing some of the minute tubes through which the water passes4 ,any fleshy stemmed plant will serve our purpose4 ,we must tear it to pieces lengthways with a needle and we shall find many threads--this is not their correct name but it expresses our meaning--running the whole length of the stem4 ,they run1 in fact1 from the tips of the root to the leaf1 and may be seen as leaf veins4 ,if we remove one of these threads and tease it with needles on a slide we shall reduce it to still finer threads4 ,by the way1 teasing in the sense we have used it here1 means separating the various parts4 ,let us examine some of these fine threads1 we shall see that some of them appear like coiled springs at first glance4 ,a more careful examination will show us long tubes with spiral thickenings4 ,we all know the garden hose-pipe with stout wire coiled round it as a protection2 these tubes may clearly be compared with the familiar hose-pipe1 where the rubber portion represents the cell wall and the stout wire the thickened parts of the wall4 ,there is1 however1 this great difference1 the wire is outside the hose-pipe1 the thickened portion of the plant tube is inside the wall4 ,these tubes are the ducts for water passing from root to leaf4 ,if the agricultural side of botany attracts us we shall not have much difficulty in finding many more objects from the fungus world than are mentioned in our chapter on ,agriculture1 whilst the study of bacteria may truthfully be termed never ending4 ,ponds and rivers teem with vegetation suitable for microscopic study4 ,the testing of foods for impurities is largely botanical work4 ,the botanist1 of all men1 need never allow his microscope to be idle4 ,our ,british insectivorous plants are of great interest and they will supply us with some objects for our microscope4 ,we only possess three different kinds of these curious plants in this country1 the ,bladderworts which live in water and the ,sundews and ,butterwort1 which frequent moist1 peaty land4 ,the pond-dwelling ,bladderworts are not rare1 indeed they occur in plenty in certain localities1 but they are not very evenly distributed over the country and in some districts one may search for them in vain4 ,it is worth while making a special effort to obtain a specimen4 ,each plant bears a number of hollow structures1 the bladders4 ,there is an entrance to each bladder1 edged with stiff hairs and closed by a trap door1 which opens inwards but will not open outwards4 ,all these parts may be seen under the microscope as may the interior of a bladder2 its walls are studded with short hairs4 ,when small water animals enter a bladder1 it is said that they do so to escape from their enemies2 they are entrapped forever1 they die and eventually decay4 ,the juices which arise from their decaying bodies are absorbed by the hairs lining the bladder4 ,the ,sundews are pretty plants1 with rosettes of reddish leaves and minute white flowers4 ,with the naked eye we can usually see many drops of clear liquid on the leaves1 a number of substantial-looking hairs and a few insects adhering thereto4 ,if we examine one of these hairs under the microscope1 we shall see that it is club-shaped2 it is1 in fact1 a hair which gives off a sticky liquid with the power of holding any luckless insect that settles thereon and absorbing its softer parts for the nourishment of the ,sundew4 ,an examination of a complete leaf with our pocket lens will show that where an insect has settled1 several of these hairs have curled over so that they touch their victim4 ,because the hairs possess this power of movement they are often wrongly called tentacles4 ,butterwort1 like ,sundew has a rosette of leaves but they are greasy looking and pale green4 ,their flowers are a pretty blue4 ,most probably we shall notice that the edges of the leaves are curled inwards1 and if we look below the curled portion we shall surely find some captured insects undergoing digestion4 ,the leaf of this plant makes an interesting object for the microscope4 ,there are two kinds of hairs on its surface1 short stout ones and longer knobbed ones2 the former give off a sticky liquid which holds any small insects that touch it1 the latter give off digestive juices4 ,while the hairs are used in digestion1 after the manner of those of ,sundew1 the leaf itself curls so that more of the hairs are brought into contact with the victim and thereby its digestion is hastened4 ,many small flowers may be examined with low magnifications4 ,when we examine them thus1 we shall probably realise for the first time how beautiful are many of these seemingly inconspicuous blossoms4 ,grass flowers are always interesting2 they are not ornamental it is true1 but that does not detract from their interest4 ,there is one part of each flower known as the stigma2 it is the part on which the pollen grain must be placed in order that seeds may be formed4 ,the pollen grains are taken to the stigmas in many ways1 but the most usual agencies are insects and wind4 ,in the case of grasses1 wind is the agency and for that reason the stigmas of grass flowers are feathery1 so that they can easily hold the pollen grains carried to them by the lightest breeze4 ,we shall probably see many pollen grains entangled in the feathery stigma of the flower we are examining4 ,in the flowers of other plants we shall find1 when we magnify them1 that there are all manner of contrivances on the stigmas1 all designed for holding the pollen grains2 hairs1 knobs1 hooks and the like4 ,an interesting collection could be made of various pollen grains1 which are easily obtained by merely dusting the anthers of flowers on to a clean1 dry slide4 ,they are varied in shape1 colour and size2 some are smooth1 some studded with spines1 others again1 those of the ,mallow for example1 have little lids which open when the pollen grain germinates4 ,the germination of pollen grains is easily observed under the microscope1 by putting a few of the grains in an exceedingly weak solution of sugar and water4 ,the vigil may be a long one1 but if the pollen grains are ripe and fresh1 and the sugary solution sufficiently weak1 the patience of the microscopist will be rewarded by the observance of the bursting of the pollen grain's coat and the outgrowth of the pollen tube4 ,other pollen grains worthy of examination1 are those of various lilies1 of ,eschscholtzia and of ,scotch ,fir2 the last named have curious little air-bladders1 for the purpose of rendering them more buoyant4 ,many lowly plants thrive in weak sugar solutions1 after the manner of pollen grains4 ,the yeast plant is one of them4 ,a very small portion of yeast1 in a drop of sugar solution1 will show us one of the simplest methods of vegetable reproduction4 ,yeast is a fungus and it is also a plant composed of only one cell4 ,under the microscope1 it appears as a colourless oval body4 ,the sugar solution causes it to multiply and1 after the lapse of a little time1 most of the yeast plants will be seen to bear outgrowths1 called buds1 which grow larger and larger till1 at length1 they break away from the parent plants and start a separate existence4 ,sometimes1 when these plants are increasing very rapidly1 the buds will bear smaller buds and these again still smaller ones till a fairly long chain of yeast plants is formed4 ,it is always interesting and also instructive to make comparisons as we progress with our work4 ,to illustrate our meaning let us compare the budding of the yeast plant with the budding of the hydra1 which is described in our chapter on pond life4 ,in the same chapter we described the division of a proteus animalcule into two separate organisms1 a process which is also undergone by bacteria when circumstances are favourable to their increase4 ,we shall find many points of similarity if we make careful comparisons1 and several important differences4 ,objects for the microscope we can find in plenty1 without going far afield4 ,the white mould which we can probably find in the larder1 on a pot of jam or other food that has been allowed to stand for some time1 will provide a good subject to start upon4 ,a little of this plant1 for such it is1 carefully lifted on to a dry slide will show the threads of the mould1 terminated by round black knobs4 ,breathe on the specimen and the moisture of your breath will cause these little balls to break and set free a quantity of fine dust-like bodies called spores4 ,the spores will be carried about in the air1 they are so light1 and if they settle on a suitable medium they will germinate and start another growth of mould4 ,the blue-green mould of cheese is constructed quite differently2 its spores are not contained in any hollow structures like those of our first object1 but grow in chains radiating from a central point1 like the outstretched fingers of the hand4 ,it is this fungus1 by the way1 which imparts the colour and flavour to gorgonzola cheese4 ,for some reason living organisms1 possessing the power of movement1 be it ever so slight1 are always more attractive than those which are apparently motionless4 ,let us study two common objects from the plant world which may easily be obtained by any nature student1 objects which owe their power of movement--not to be confused with locomotion1 by the way--to the presence or absence of moisture in the air4 ,on the under side of the fronds of many ferns there will be found more or less rounded reddish-brown spots4 ,these outgrowths1 for such they are1 vary in position and shape according to the species of fern4 ,an examination1 with a pocket lens1 will show that these brownish spots consist of minute tufts of knobbed structures1 growing from the tissues of the frond4 ,sometimes the structures are naked1 sometimes covered with a membrane4 ,in either case1 one or more of the knobbed structures is worth examining under the microscope2 we shall then see that it consists of a stalk terminated by a thin walled portion1 shaped like a bi-convex lens4 ,round the edge of the greater part of this lens-shaped portion there is a much more substantial-looking rim4 ,within the lens-shaped part we can easily see brown spores4 ,if we have chosen our object at an opportune moment1 any excessive moisture in the air will cause the thick-walled rim to straighten itself out1 tearing away the thin-walled1 lens-shaped part in so doing and setting free the spores4 ,closely related to the ferns1 the horsetails provide another interesting object for the microscope4 ,the fertile shoots of these plants1 somewhat resembling asparagus1 though in reality belonging to an entirely different family1 will1 when gently tapped on a clean dry microscope slide1 leave behind a pale yellow powder4 ,the powder consists of spores1 and most interesting they are4 ,when dry1 each spore will be seen to have four somewhat thread-like outgrowths1 flattened at the end2 breathe on the spores and each of the outgrowths will coil up so as to form a complete covering for the body of the spore4 ,as drying takes place1 these outgrowths gradually uncoil again4 ,we have mentioned spores several times in this and other chapters4 ,strictly speaking a spore cannot be compared with a seed1 but for our purpose it is sufficient to know that spores are more or less seedlike in appearance and that they give rise to new plants when they germinate4 ,they are found in all ferns1 on horsetails1 these odd plants with their creeping stems and rings of scale-like leaves1 on club mosses1 mosses proper and fungi but not on flowering plants4 ,should the student of plant life not yet be satiated with following the suggestions we have made1 he can turn his attention to fruits and seeds and the contrivances designed for their distribution4 ,the fruits of goosegrass1 popularly known as cleavers1 are studded with little hooks so that they may adhere to any passing animal4 ,the fruits of ,burdock are similarly armed and if we make a study of fruits and seeds we shall find that this is a very common method of ensuring distribution4 ,there are also a number of seeds covered with hairs which render them buoyant2 those of the willow herb are easily found1 so too are the fruits of dandelion1 thistle and groundsel4 ,these and many more will give us many an interesting hour1 towards autumn4 ,,chapter ,,viii ,,animal ,,life ,,and ,,the ,,microscope ,there are few more interesting animals than spiders and we may spend many an hour learning details of their structure1 which only the microscope can show1 and studying their habits1 for only by doing so is it brought home to us how astonishingly clever they are4 ,the spider1 of course1 is not an insect2 it has eight legs1 whereas the insect has only six1 its head and thorax are fused1 but in the case of insects head and thorax are separate4 ,there are many other1 less evident1 points of difference as we shall see4 ,for the microscope1 there are few better objects in animal land than the feet of spiders4 ,their study will give us plenty of occupation for they are modelled on various plans1 according to the different kinds of spider4 ,taking the common garden spider as our first example we shall find that its foot is a most ingenious contrivance4 ,our microscope will show us that the foot is armed with a pair of comb-like claws4 ,a little study of the habits of the spider will enlighten us concerning the uses of these combs4 ,at this point we may remark that the examination of living creatures beneath the microscope should1 whenever possible1 go hand in hand with a study of habits4 ,over and over again in our microscopical investigations we shall come across structures which appear to be useless as far as we can surmise4 ,a careful observation of the living owners of these puzzling structures will probably clear up the whole matter4 ,well1 let us watch a garden spider2 if we do so intelligently we shall see two uses of these combs and may guess the third4 ,the spider uses its combs as we do1 to straighten its hair2 they also clean its body4 ,it uses them to obtain a firm grasp of the threads of which its web is composed and1 though we cannot see this1 so quick are the movements of the creature1 the combs serve a very useful purpose in holding captured prey4 ,the garden spider and its relatives are distinguished by the fact that1 in addition to the two large comb-like claws1 they possess a third smaller claw and some toothed spines4 ,the small claw and toothed spines are movable and1 when pressed against very firm grasp4 ,with these cleverly contrived feet she--it is always the lady spider who makes the web and does all the work--hauls in the slack of the combs of the larger claws afford their owner a her web and owing to their firm grasp she can run readily over its meshes4 ,the house spider1 which spins a web seemingly in a disordered tangle and quite unlike the beautiful web of the garden spider1 has feet of a different pattern4 ,the most interesting feature about the legs of this creature is the wonderful double comb with which it teases out the threads of its web as they are formed4 ,this comb takes the form of a double row of minute1 curved spines on the last joint but one of the hind legs2 it must certainly be examined under our microscope and we should try to see the combs being used by the spider4 ,we must also make a point of examining the feet of a wolf spider for they are constructed on a different plan to those of the spiders we have mentioned4 ,wolf spiders are the creatures which spin no proper web but lurk in holes in walls or in the ground and dash out from their hiding places to seize their prey4 ,they usually line their lairs with silk4 ,we shall have more to say about wolf spiders in a moment4 ,the ,zebra spider1 which belongs to the family of jumping spiders1 has very curious feet1 not so much on account of its claws as because of the curious clubbed hairs which adorn them4 ,this little spider is black1 with white stripes on body and legs2 the peculiar habit1 for a spider1 of leaping upon its remarkable hairs on its feet render it exceedingly sure-footed and it has need to be1 for it exhibits prey4 ,there are many other spiders which we may examine with the certainty of finding some features of interest1 the ,drassid spiders which lurk beneath bark and stones2 the crab spiders usually brightly coloured little fellows with the habit of living in flowers2 the little money-spinners and the harvest-men2 these last are not true spiders but they are none the less interesting1 they are the small-bodied1 very long legged creatures which occasionally find their way into our houses4 ,having taken our fill of the spiders' feet we may well turn our attention to their heads4 ,if we have caught a spider in the act of killing a struggling fly1 it must have struck us that one bite from the spider is sufficient to kill its victim4 ,let us see if we can find the jaws which so quickly bring death even to large insects4 ,we shall require a steady hand and some little skill to examine them properly but the task is not beyond our powers4 ,having killed our spider we must snip off its head1 place it on a slide and examine it with a low magnification4 ,looking straight at the face1 we can plainly see the sharply pointed1 hinged jaws2 in nearly all spiders they work from side to side and they can be closed on their hinges like pocket knives4 ,with a pair of mounted needles and two steady hands1 let us dissect the head of our spider1 so that we obtain one of the jaws quite free from its surroundings4 ,at the base we shall find a little sac1 the poison gland1 and if we now magnify the jaw much more highly we shall observe a tiny hole very near the tip4 ,when the spider has grasped her prey in her jaws she causes the poison from the poison glands to pass into the body of her victim1 by way of the little hole in her jaw2 the poison causes paralysis and the victim struggles no more4 ,the only excuse we can make for spending so much time with the spiders is that they are of the greatest interest to the microscopist4 ,returning to our friend the garden spider we must examine the spinning organs1 known as spinnerets4 ,these are to be found near the tip of the abdomen on the under side4 ,there are six pairs in all in the garden spider but the middle pair are shorter than the others and1 in consequence1 not easily seen4 ,the tips of the fleshy little spinnerets should be highly magnified and we shall notice that the structure of the tips differs in each pair of spinnerets4 ,on the foremost pair1 there is a fairly large projection and numerous small ones2 on the middle pair three large projections and many smaller ones1 whilst on the hind pair1 in addition to the small projections there are five large ones4 ,the large projections are called spigots and the small ones are known as spools2 from the former is derived the strong silk of the web1 from the spools the fine threads issue4 ,on the underside of our garden spider there is a dark patch and1 just in front of this dark spot1 are a pair of slits4 ,these we must open up very carefully1 in a dead specimen of course1 and within1 if we have succeeded in our dissection1 we shall see from fifteen to twenty little flaps resembling the leaves of a book1 in fact they are known as lung books and1 by means of them1 the spider breathes4 ,one more word and we must leave the spiders4 ,the eyes must be examined in every specimen4 ,most spiders have eight eyes1 set like little gems in the front part of the head2 some have six eyes1 some only two and a few kinds are eyeless1 but these last spend all their lives in dark caves1 so eyes would be useless to them4 ,when we examine the eyes of wolf spiders we shall observe that they are placed on the tops of little projections so that their owners may better be enabled to see all around them4 ,the hairs and scales of many spiders make beautiful objects for the microscope4 ,we must make a point of examining the hairs of the water spider also the scales from the ,zebra spider4 ,the latter with their feathery form and iridescent colouring1 are particularly beautiful4 ,we may advantageously spend a moment or two in the examination of the spider's web and the threads of which it is made4 ,the strands radiating from the centre of the web differ from those which are arranged spirally4 ,the latter are covered with a sticky substance as may be seen under the microscope4 ,when these spiral threads are laid down by the spider1 the sticky substance covers their whole length in a thin film1 but the little architect adds a finishing touch1 by pulling the thread as a bowman pulls his bow and then releasing it suddenly4 ,the result of this performance is that the sticky substance forms a series of minute globules over the whole length of the thread4 ,in order to be in a position thoroughly to master the details of animal structure it is necessary to have acquired sufficient skill to cut sections4 ,they cannot1 however1 be cut so easily as is the case with plant sections4 ,the various parts of animals are either so hard1 e4g41 bones and teeth1 that they must be treated almost as pieces of rock and rubbed down till they are transparent1 or they are so soft that they require soaking in various chemicals to make them harder and even then it is usually necessary to imbed them1 i4e41 surround them with some easily melted substance which sets moderately hard1 such as paraffin wax4 ,cutting sections of animal parts is beyond the average amateur4 ,the feathers of birds make beautiful objects for the microscope4 ,for those microscopists who desire beauty of colour rather than details of structure it is hard to beat the glorious shades of certain feathers beneath the microscope4 ,to obtain the best effect a fairly low magnification should be used and all manner of lighting thrown upon the object1 for we have all seen the feather which appears drab at one angle is of the greatest brilliance at another4 ,various feathers and from various parts of birds should be examined1 if we desire to understand their structure4 ,each feather consists of a vast number of cells but it is improbable that we shall be able to prove this statement by the examination of any large feather4 ,we must take a down feather1 notice carefully the arrangement of its various parts1 for it will be interesting to compare this soft1 weak feather with a comparatively strong flight feather from a wing4 ,now1 under a higher magnification1 we can plainly see the little cells of which the down feather is built up4 ,one of the strong wing feathers of such a bird as a pigeon is of the greatest interest as a microscopic object4 ,we must take a few of the barbules1 the slender1 flattened portions of the feather which fringe either side of the barb4 ,a moderately high magnification will show how ingeniously they are contrived4 ,the hinder side of each barbule is a moderately thick upwardly curved edge whilst1 on the forward side1 there is a row of curved hooks4 ,when the feather is neat and tidy1 and its owner when in good health usually sees to it that its feathers are well kept1 the hooks of one barbule engage with the curved edge of the next barbule4 ,the feather1 by means of this ingenious locking device1 becomes much more nearly a solid structure than would be the case if the barbules did not hook on to one another4 ,the arrangement for hooking together the fore and hind wings of bees and wasps is very similar4 ,we may examine a number of flight feathers but we shall not find any very striking differences between those of various birds4 ,all1 apparently1 follow a common design4 ,from feathers to hair and from hair to horns and some scales is not a very far cry4 ,we have talked about the examination of hair in another chapter1 so we will not repeat ourselves here4 ,scales we shall most of us have opportunities of examining in plenty4 ,we have just mentioned that some scales are comparable to hairs and feathers4 ,such scales are to be found in snakes and lizards4 ,the scales of fish are of a different order but they are equally or even more interesting when examined under the microscope4 ,if we live in a district where many and various fish are caught we shall soon discover that their scales differ in a remarkable degree4 ,some are of the texture of horn1 some are gristly1 some bony and some covered with enamel1 after the manner of teeth4 ,not only do they differ in texture but in design as we shall see in a moment4 ,certain fishes1 the eel is one1 the mackerel another1 are said to be scaleless4 ,as a fact their scales are very thin and transparent and so arranged that they are less evident than those of other fish4 ,by taking a little of the skin of one of these fish we can easily detach a few scales for examination4 ,those of the eel we shall find are very thin and delicate and quite transparent4 ,these and all other fish-scales may be made into permanent slides by mounting in ,canada ,balsam1 as described in our last chapter4 ,the carp1 whiting1 salmon1 sprat1 herring and many other fish have scales called cycloid or circular2 the term is rather a misnomer because they are not truly circular1 but the name is used to distinguish them from other scales4 ,the structure is easily made out with a moderate magnification4 ,many of these scales1 however1 exhibit portions more dense than the rest2 these dense spots are caused by little particles of lime which may be seen under a higher magnification4 ,illustration3 #a4 ,a ,,thorn ,,insect4--,a striking example of protective resemblance4 ,when resting on a thorny twig this little insect is safe from all its enemies4 #b4 ,,the ,,head ,,of ,,palm ,,weevil4--,the long snout distinguishes the weavils from all other beetles4 ,its very long front legs are also worthy of notice4 #c4 ,a ,,leaf ,,insect4--,green in colour1 this insect bears a remarkable similarity to a leaf4 ,its sluggish habits heighten the illusion4 #d4 ,,the ,,head ,,of ,,stick ,,insect4--,there are few more curious insects than the stick insects4 ,the specimen illustrated has a very bird-like head4 ,perch1 pike1 sole and some other fish have much more peculiar scales1 known as ctenoid or combed for the reason that their unattached1 that is to say their hinder margins1 are toothed like a comb4 ,the scales of sharks1 dog-fish and rays are called placoid for they are toothed2 not only so but their arrangement is frequently quite dissimilar to the scales of ordinary fish4 ,taking the herring as our example1 but a salmon or any other fish would serve equally well1 and examining the arrangement of its scales with the help of our pocket lens1 we shall find that the scales are fixed to the fish by their forward edges and that each scale partly overlaps its neighbour1 as do tiles on a roof4 ,in the shark family1 however1 the scales are often relatively wide apart1 they do not overlap but are imbedded separately in the skin4 ,the scales of rays have each a hard spine projecting from the centre1 those of sharks and dog-fish have teeth1 and they are teeth not only in appearance but also in structure4 ,the ganoid scales of sturgeon we are hardly likely to meet with4 ,sometimes these fish are on sale in ,london and other large towns and a specimen of their scales may be procured4 ,they are bony in structure and1 though interesting1 require a considerable amount of preparation to render them sufficiently transparent to be examined under the microscope4 ,it is interesting to note that all the fossil fish which are discovered from time to time have either ganoid or placoid scales1 a fact which shows that the sharks1 rays and sturgeon are directly descended from creatures which swam the seas thousands of years ago4 ,the shells of shell-fish are not easy to examine microscopically1 but frequently their plates may be detached from the edges of such shells as oysters and mussels and these should be examined4 ,if the outer part of the shell be taken we can easily see its honeycomb structure and1 by adding a little acid and waiting till all action has ceased1 we shall have a structure remaining which is remarkably like a number of plant cells4 ,the inner layer of many of these shells is composed of beautifully iridescent mother-of-pearl4 ,now such iridescence is usually caused by surfaces furrowed with many very fine lines and mother-of-pearl is no exception4 ,under the microscope1 with a moderately high magnification1 we can see minute striations all practically parallel to one another4 ,the cuttlefish is peculiar in having a skeleton which is a moderately soft plate4 ,these plates can often be found washed up by the tide1 may be cut out from a dead cuttlefish or bought from a chemist's as cuttlefish bone4 ,however we secure the material we shall find that one side of the 8bone0 is hollow and that across this hollow1 delicate plates run parallel to one another at intervals4 ,between these parallel plates there appear to be a number of fibres but1 if we cut a thin slice of the structure and examine it under the microscope1 we shall see that the apparent fibres are really very thin plates of bone which wind and double upon themselves in a beautiful manner4 ,the structure of these plates gives strength to the bone without adding to its weight4 ,snails are sure to attract the microscopist sooner or later1 so too are slugs4 ,many of the latter have shells1 small flat or ear-shaped shells1 quite different to the portable homes of snails4 ,in many young snails1 which may be killed by dropping into boiling water1 we can find the shells so transparent that they form good objects for our microscope4 ,sometimes they are composed of six-sided cells1 sometimes of beautiful star-shaped cells4 ,from the microscopist's point of view the most interesting feature of the snail is its rasping organ1 often wrongly termed the tongue4 ,to find this organ it is necessary to open up the mouth of a dead snail1 and if we seek the assistance of our lens while doing so1 we shall have no difficulty in finding the rasp--it may be recognised by the minute teeth with which it is furnished4 ,the whole structure should be carefully removed and mounted upon a slide4 ,in some kinds of snails there are but a hundred teeth1 other kinds1 however1 possess as many as twenty-six thousand eight hundred4 ,the snail makes use of this remarkable organ to procure its food4 ,vegetation is pressed against a plate at the top of the creature's mouth and literally filed into small pieces by the rasping organ4 ,captive water snails may be watched while using their rasp upon the water plants or upon the green slime which soon accumulates in aquaria4 ,the eggs of snails are easily found and should be examined1 the queer little inmates may be studied through the transparent shells1 in all stages of development4 ,the naturalist whose inclinations lead him towards the study of animal life will find plenty to occupy his time and his microscope4 ,all kinds of eggs of small creatures may be watched as they develop4 ,frogs' eggs are of interest in this respect1 so too are tadpoles which hatch from them4 ,the whole blood circulation in a young tadpole may easily be studied under the microscope1 the structure of the external gills1 the gradual change to internal gills1 the development of legs1 the absorption of the tail4 ,the tadpole and its marvellous changes will afford sufficient microscopic material to last for many weeks4 ,,chapter ,,ix ,,the ,,study ,,of ,,the ,,rocks ,the study of rocks and minerals by means of the microscope is apt to be disappointing4 ,in the first place1 to study them seriously we require a special microscope1 the ordinary instrument1 with which we may poke into the deepest secrets of the animal and plant world cannot translate for us half the story of the rocks4 ,again1 to understand rocks and minerals we must study them somewhat deeply4 ,geology1 as the science of rocks is called1 is no more difficult than botany or zoology1 the sciences of plants and animals respectively4 ,botany and zoology1 however1 appeal in some degree to nearly all of us2 we may learn a good deal concerning the structure of the cockroach with the help of our microscope and be interested in the revelations of our instrument1 but to embark on a detailed course of the minute internal anatomy of insects would appeal to few of us4 ,animal or plant life may be studied piecemeal and enjoyed on account of its absorbing interest4 ,geology must be studied from its very beginnings if we are really to understand what we see beneath the microscope4 ,in the hand1 a lump of rock1 say of granite1 may be of exceeding beauty4 ,the body of the rock is1 perhaps1 a delicate pink1 scattered here and there are the flat glittering plates of mica and brilliant crystals of quartz4 ,other rocks1 less common1 vie with the rare gems for beauty of colouring and lustre4 ,as thin microscope sections these once gorgeous specimens are colourless1 dull and1 unless we understand them1 uninteresting4 ,there are1 however1 many mineral substances which we may study with advantage for1 if our investigations do not take us very far towards elucidating the story of the rocks1 we shall at any rate discover something that is new to us4 ,we may well commence our studies with the examination of ordinary sand4 ,this is not a rock1 you will probably exclaim4 ,you are right but one day it may be a rock1 it all depends upon circumstances4 ,before we take out our microscope let us have a short talk about rocks in general1 then we may understand better where we are4 ,rocks of one kind and another make up the crust of the earth1 that is pretty obvious anyway4 ,thousands and thousands of years ago1 how many we are not prepared to guess1 this old earth of ours was a sphere of molten rock4 ,needless to say it was far too hot for any plants or animals to dwell upon it4 ,very1 very gradually the outer crust cooled down and in time it became sufficiently cool to support animal and vegetable life4 ,then there were rivers and seas and then came1 from time to time1 rain and wind and frost and even earthquakes4 ,the earthquakes cracked the crust of the earth1 moisture entered the cracks and1 when the frosts came1 pieces of rock were broken away1 owing to the expansion of the moisture in the cracks as it became converted into ice4 ,the rain and wind helped to carry the broken pieces of rock1 ever downwards towards the sea1 but before the sea was reached the big boulders became broken up1 by their buffeting1 into shingle and sand and mud4 ,in the course of long ages1 longer than it is easy to imagine1 these broken pieces of rock1 gathered together as we have seen from various districts1 may have been left high and dry1 for the face of the earth has not always been as we know it now4 ,in time all the little particles became welded together to form a new kind of rock4 ,sometimes animals and plants were buried in the mud destined to become a rock and their parts were so well preserved that they may not only be recognised by present-day scientists1 but in many cases their structure may be made out so well with the aid of a microscope that no one would guess they had been buried thousands of years ago4 ,new rocks have been formed not only by the breaking up and welding together of the original earth's crust1 but by animal and plant remains4 ,in some places1 in past ages1 billions and billions of little shell-fish have lived in the waters1 died there and their shells have fallen to the bottom of their watery home4 ,now we know their shell remains as chalk or if it has undergone great pressure1 owing to changes in the earth's surface1 as limestone4 ,there are rock masses also formed of the remains of countless ,diatoms2 sponge spicules1 too1 have played their part in rock formation4 ,it is clear from what we have written that1 in the first place1 the rocks of the earth form two great divisions1 the rocks which formed the original crust of the earth1 ,primary rocks they are called1 and the later-formed ,secondary rocks4 ,the ,primary rocks are often glassy in appearance1 they show unmistakable signs of having once been molten and they never contain animal or plant remains1 fossils as they are called1 for the reason we have already explained4 ,the secondary rocks often betray their origin by occurring in layers1 or strata to speak more scientifically4 ,always when we think of the rocks we must think in thousands of years1 then it will be easier to understand the formation of these strata1 each one of which may represent the work of hundreds and hundreds of years4 ,now to return to our sand2 we have explained briefly that sand is really the remains of broken up rocks4 ,first we have the solid rock1 boulders are broken from it as the boulders are acted upon by rain1 frost and wind3 they become more and more broken up and at the same time they are carried towards the sea where they take the form of shingle4 ,the shingle1 in the course of time1 becomes broken up into sand1 and the sand again becomes so finely divided that it forms mud4 ,from this it is clear that the composition of the sand depends largely on the nature of the rocks in the neighbourhood4 ,illustration3 ,by the courtesy of ,messrs4 ,f4 ,davidson ,co4 #a4 ,,foraminifera ,small sea shells4 ,the inmates die and the shells1 falling to the bottom of the sea1 are gradually converted into chalk4 #b4 ,,diatoms ,small water plants which make beautiful objects for the microscope by reason of their remarkable shapes and sculpturing4 ,first of all1 we must place a little of our sand upon a piece of black paper and examine by reflected light4 ,we shall soon notice that sand is anything but the simple gritty looking substance it appears on the sea shore4 ,at least four different substances are certain to be seen2 if the sand be clean1 we shall see bright glassy crystals of quartz2 angular1 sharp-edged pieces of flint2 minute1 flat1 glistening plates of mica and the broken remains of shells4 ,should our sand be taken from a spot in the vicinity of volcanic rocks1 it will probably contain opaque pieces of magnetite2 we may not recognise these when we see them1 but they may be separated from the rest of the sand by means of a magnet1 to which they will adhere4 ,probably our sample of sand will be dirty or stained with iron1 in this event we may wash it with weak acid1 then after drying1 we may examine by transmitted light and the various crystals will show up well4 ,let us take some clay as our next example4 ,clay is the substance from which the rocks known as shale and slate have been formed4 ,we cannot see much of the structure of clay with our microscope so let us wash it and1 by so doing separate it into its components4 ,we must put a little clay into a tumbler of water and stir it vigorously for some little time1 then still stirring1 if we pour off the muddy liquid into another tumbler1 we shall find that our old friend sand has settled to the bottom4 ,clay then is merely mud and sand1 but we must not throw this sand away without examining it for1 very frequently1 beautiful minute fossils are to be found amongst it4 ,little creatures dwelling in the mud1 become buried in it and1 as more and more mud is formed above them1 and it becomes partly solidified in the form of clay1 they become fossilized4 ,if now we examine a piece of sandstone with our pocket lens we shall find that it very closely resembles the sand we have already studied4 ,it may be so soft that we can break it up in our fingers1 then if we examine the powdered sandstone beneath the microscope we shall need to be experts to tell whether we are examining sand or sandstone4 ,should our rock be too hard to break up in our fingers the addition of a little weak acid will reduce it to sand4 ,we see now that a large proportion of sand and a small proportion of mud result in the formation of sandstone1 whereas if the proportions are reversed and we have more mud than sand the resulting rock is known as shale or slate4 ,in shale we very frequently find fossils1 in sandstone rarely1 for the reason that structures buried in the mud1 destined to become shale1 are protected from the atmosphere and the action of water2 sandstone1 on the other hand1 is porous1 moisture trickles through it and any delicate structures which may have been buried in it are more likely to decompose than to become fossilized4 ,limestone is easy to obtain and may occupy us for a few moments4 ,we do not wish to go into technical details1 but we may say that the word limestone includes a number of rocks which differ largely in appearance and to a considerable extent in composition4 ,it would1 perhaps1 be more correct to say that there are several kinds of limestone4 ,some kinds are made up almost entirely of shells and very interesting they are as microscopic objects4 ,one may wonder how a geologist can state with certainty that some spot1 may be many miles from the sea1 was once covered by salt water4 ,one of these shell-formed limestones may give him the information2 he knows that certain shells comprising the rock must have belonged to marine animals1 he knows too that whole mountains1 which these rocks sometimes form1 are not carried bodily on to dry land1 so the obvious inference is that the rock was formed below the sea4 ,the softer limestones may easily be crumbled and powdered for examination under the microscope2 the harder kinds should be treated with acid4 ,when acid is added to limestone a considerable effervescence takes place1 for the acid decomposes a substance known as calcium carbonate1 which the limestone contains1 and bubbles of gas are given off4 ,when the limestone has ceased to effervesce the portions of the rock which remain1 may be carefully washed in water1 dried and examined under the microscope4 ,we shall find that the substance we examine consists of sand containing a goodly number of plates of mica and there may also be a number of sponge spicules4 ,we must bear in mind when we are examining the remnants of limestone after treatment with acid1 that shells are largely composed of calcium carbonate1 so it is useless to look for any shell remains1 for the acid will have dissolved them4 ,calcium carbonate1 in a nearly pure state1 will and does form rock-like structures2 we are most of us familiar with stalactites which are formed on the roofs of caves4 ,these structures are usually composed of calcium carbonate though sometimes1 notably in some of the ,derbyshire caves1 ,barium takes the place of ,calcium4 ,should we have the chance of examining a section of a stalactite we should certainly do so4 ,we can see the rings which are formed1 as layer after layer of calcium carbonate is deposited1 in fact the section of a stalactite bears a striking resemblance to a stem of a tree and has1 before now1 been mistaken for a fossil stem4 ,if the study of rocks appeals to us we should make a point of examining all the specimens we can lay hands upon4 ,many quite common specimens may easily be obtained2 rock-salt1 for example1 though in itself not of great interest as an object for the microscope1 will readily dissolve in water1 leaving behind an insoluble residue of iron which is well worth examination4 ,the majority of rocks1 however1 are not affected by water and but little by acids4 ,with such specimens the only course open to the microscopist is to prepare sections4 ,the making of rock sections is certainly different to the cutting of plant or animal sections4 ,it is a laborious business as the enthusiast will find to his cost4 ,the professional makers of rock sections have special grindstones or lathes for the purpose and1 even so1 the process is not rapid4 ,the amateur must needs do all his preparation by hand4 ,the requirements1 in addition to the piece of rock of which we require a section1 are a small square of plate glass1 some ,canada ,balsam1 emery powder of various grades and an unlimited stock of patience4 ,if possible we choose a piece of rock with one side as nearly as possible flat2 this is merely to save labour2 the piece of rock should be roughly about half-an-inch square4 ,as a start we rub the flattest side in a mixture1 practically a paste1 of coarse emery powder and water4 ,as a matter of fact1 we may keep the piece of rock in our pocket and grind it when occasion offers on a flat stone wall or on any surface that will assist in producing a flat surface4 ,when we have ground our surface flat and smooth1 we finish it off with fine emery powder and may then polish it with jeweller's rouge4 ,so much for the first side and1 if we do not cry enough at this period1 we may proceed to the grinding of the other side4 ,taking our slab of plate glass1 we fasten the polished side of our piece of rock to it by means of ,canada ,balsam1 then we may rest for a few days while the ,balsam sets4 ,as soon as the rock is firmly fixed to the glass we proceed as before1 but in this case the final grinding and polishing must be very carefully carried out4 ,towards the end of the operation our original lump of rock will be reduced to the thinness of a cover slip and to its fragility4 ,having given the finishing touches with jeweller's rouge1 we put the glass1 with its attached rock section into a bottle of xylol 7to be obtained from any chemist74 ,the xylol dissolves the ,canada ,balsam and the rock section falls from its support4 ,a further washing in clean xylol should be given and then the section is ready for mounting1 which is best done in ,canada ,balsam4 ,the section may be carefully fixed to the slide with a drop of ,balsam or it may be covered with a cover slip1 in the usual manner4 ,in our concluding chapter we give hints on slide making and addresses of firms who supply slides4 ,our advice in that chapter is to prepare one's own slides where possible2 in the case of rock sections1 however1 we must change our advice1 only the microscopist of unlimited leisure can find time to make his own slides4 ,one of the most interesting branches of rock study deals with the fossil remains of plants and animals4 ,fossils are interesting in themselves3 they are doubly interesting because they tell us more than we could ever have discovered without them1 concerning the living forms which inhabited the earth at different periods4 ,geologists know the order in which the various secondary rocks were formed and by studying the fossils of these various rock formations1 from the earliest to the latest1 can tell which animals and plants have been longest upon the earth4 ,some of the living forms of to-day have existed from very early times2 we know1 for example1 that cockroaches were upon the earth long ages ago1 for their fossil remains are found in the very early rocks4 ,for the most part the fossils of animal forms do not make good objects for the microscope4 ,the ,foraminifera1 minute creatures dwelling in shells1 are the most suitable for microscopic examination and very beautiful some of them are4 ,they are best examined by reflected light1 for then their little shells show their delicate pearly sheen4 ,sponge spicules1 as may be guessed from their hardness1 are common in the fossil state2 there are also fossils of sea-anemone ancestors and fossils also of ,hydra colonies4 ,the last named1 known as graptolites1 look not unlike lead-pencil marks on the rock4 ,they exist in many forms2 ,diplograptus has a stem with two rows of cups in which the little creatures lived long ages ago2 ,monograptus has but one row of cups upon its stem1 whilst ,didymograptus is a branched form4 ,these fossils are by no means rare and are worth studying under the microscope4 ,there are curious fossils knows as ,trilobites1 not unlike the present-day wood lice2 they too may be studied1 for some of them show all their characteristic markings as plainly as they must have appeared on the living animals4 ,in the plant world1 many fossils in amazingly1 good states of preservation have been found4 ,some of the giant ,club ,mosses from the coal measures1 exhibit all the characteristic stem markings1 leaf scars and the like1 so clearly that one might imagine one examined a living specimen4 ,most of the plant remains are beyond the reach of the amateur1 but many of them may be viewed in museums1 in different parts of the country and the microscopist1 whether he be a student of rocks or a lover of plants1 should make a point of examining them4 ,from quite fragmentary remains1 scientists have been able to conjecture what vegetation covered the earth at various ages4 ,the present is the age of flowering plants1 but long ago the world was green with giant ,club ,mosses and ,horsetails1 very humble plants at the present time4 ,,chapter ,x ,,the ,,microscope ,,as ,,detective ,it is an unfortunate fact that our food is not always absolutely pure4 ,it may be contaminated with foreign matter either by accident or by design4 ,however careful the manufacturer may be in1 say the preparation of cocoa1 some dust1 some waste vegetable matter1 perhaps even a few stray dried insects may occur as impurities4 ,they are out of place certainly but1 at the worst1 they are a sign of lack of care on the part of the manufacturer4 ,there is another1 more serious side to the question of food adulteration1 where the foreign matter is added purposely1 either because it is cheap1 because it weighs heavily1 imparts a pleasing colour or an agreeable aroma4 ,such adulteration is a form of fraud and the microscope is an invaluable aid in its detection4 ,in many respects the microscope is a better informant than the tests of the chemists2 in some cases1 however1 it merely supplements and confirms the chemical results4 ,let us consider1 for a moment1 the advantages possessed by the microscope and also where chemistry scores4 ,very frequently the results of costly law cases hang on the reports of expert food examiners2 every care1 therefore1 must be taken to avoid error4 ,this being the case1 whenever possible1 chemical tests should be carried out to confirm the results of microscopic examination4 ,when both microscopist and chemist come to the same conclusion1 there is not likely to be any mistake4 ,there are tests which the microscope cannot perform1 there are some1 also1 which are beyond the powers of the chemist and many which are very difficult for him4 ,a drop of milk1 for example1 examined under the microscope shows a number of fat globules floating in a watery liquid4 ,however clever the microscopist and however accurate his instrument1 he cannot tell if there is an excessive quantity of water1 yet a simple chemical test will answer the question4 ,this is a case in which the microscope is of little use1 although it is only fair to add that microscopic examination would reveal the presence of blood1 hair and dirt1 to mention three common impurities1 which the chemist in his test for watered milk would quite overlook4 ,with a little care and the use of suitable stains1 any bacteria which might be present would also show plainly under a powerful microscope4 ,now for an example or two where the microscopist has the advantage of the chemist4 ,some jam makers have been known to be sufficiently unscrupulous to sell 8raspberry0 jam contaminated with a large percentage of some cheaper fruit1 such as gooseberry4 ,the seeds of the two fruits differ so markedly that it is really not necessary to employ a microscope to discover the fraud1 but a case is on record where wooden seeds were used1 so like the true seeds of the raspberry1 that a very careful examination was necessary to show what had happened4 ,in our chapter on the ,microscope in ,agriculture we have referred to this point in greater detail4 ,starch of various kinds is a very common food adulterant and the experienced microscopist can estimate almost precisely1 the proportions of different starches in a mixture1 a feat which would sorely puzzle the chemist4 ,so in certain cases the microscope is indispensable4 ,briefly the microscope is a time saver2 chemical tests occupy a considerable time2 microscopic examination is quick1 the experienced microscopist at once recognises what he observes4 ,very small quantities can be examined under the microscope1 relatively large quantities are required for chemical tests4 ,again1 if only a small quantity of the material is available for examination and it is necessary to carry out chemical tests1 they can be performed under the microscope and this point is considered in another chapter4 ,we have mentioned that starch of various kinds is a common adulterant of many foods and the budding food analyst might do worse than learn to recognise the various starch grains under the microscope4 ,they are easily obtained and as easily observed4 ,each variety of starch has grains which are remarkably constant in their characteristics4 ,a beginning may profitably be made with potato starch1 for its grains are large and they possess certain well-marked features1 which may or may not be present in the grains of other starches4 ,by scraping the newly cut surface of a potato we can obtain thousands of starch grains4 ,the surface of the potato must not be grated1 just a gentle scraping with a pocket knife and a mere speck of the cloudy liquid that is obtained1 added to a drop of clean water on our slide1 will suffice4 ,cover the object with a cover glass and examine under a fairly high magnification4 ,there are countless1 oval1 almost transparent bodies in our field of view1 they are potato starch grains4 ,each one1 as we shall see when we make a more careful examination1 is not unlike a miniature oyster-shell4 ,in the shell1 there is a point which is its oldest part and the remainder has grown1 layer by layer1 round that point till the shell is fully formed4 ,now we magnify the starch grains as highly as possible and slowly rotate the fine adjustment to and fro1 for the reason that the object is not flat and by doing so1 we obtain all its parts in focus in turn4 ,if the illumination is not too intense1 we shall notice a minute dark dot corresponding to the oldest part of the oyster shell2 it is1 in fact1 the oldest part of the starch grain4 ,around this point we can see as we focus up and down1 ring after ring where the grain has grown larger and larger4 ,the dark spot is called the hilum and the rings are known as striations4 ,in the potato starch grain the hilum is not central and the striations are not circular4 ,wheat has large and almost round grains without a hilum or striations1 those of ,barley are very similar but smaller and not so uniformly round4 ,rye grains are frequently cracked and often have ragged edges4 ,a very large number of these objects may be examined1 for it is useful to know their structure if one's object be to examine various foods2 from the point of view of beauty1 when examined with a polariscope1 they have few rivals4 ,maize starch1 which is to be found in most houses under the name of corn flour consists of two kinds of grain4 ,some are many sided and angular1 all of one size and without striations1 they are also split at the centre2 the other grains are rounded1 of various sizes and are never like the angular grains grouped together4 ,the former come from the horny part of the maize1 the latter from the floury portion4 ,rice starch is also many sided and angular1 almost crystal like2 there are1 however1 never any rounded forms and this serves to distinguish it from maize starch4 ,the shape of ,arrowroot starch grains varies according to the plant from which it is derived1 for this substance does not all come from one kind of plant but1 whether the grains be pear shaped1 hammer shaped1 triangular or dumbell shaped they all show striations and an x-shaped split in place of a hilum4 ,tapioca starch grains are usually grouped together in twos or threes2 when they rest on their flat surfaces they appear circular and each hilum is surrounded by a dark ring1 when on their sides they are seen to be sugar-loaf shaped4 ,many more starches can be found without going far afield1 ,sago1 ,peas1 ,beans1 ,lentils and ,bananas are a few common commodities containing starch4 ,an effort should be made to study the very curious dumbell shaped starch grains of the ,spurge and its relations4 ,all these plants contain a white milky juice in which the starch grains float2 by squeezing a little of this milky fluid into a drop of water on a clean slide the grains can easily be observed4 ,it is sometimes difficult to observe starch grains till a fair amount of experience has been gained in the use of the microscope4 ,should this difficulty arise1 it may be overcome by adding a drop of a weak solution of iodine4 ,this will stain the starch grains a deep blue colour and render them very easy of observation4 ,the iodine solution must be weak1 however1 or the staining will be excessive and the objects rendered black and non-transparent4 ,having examined many or all of the specimens we have mentioned let us turn our attention to some of the common foods1 and learn some of the methods used in testing for impurities4 ,ordinary household bread1 it is hardly necessary to state1 is rich in starch and1 by trying the iodine test1 mentioned above its presence is easily shown4 ,with a weak solution the deeper the blue colour produced1 the greater the quantity of starch4 ,some parts of the bread will be stained yellow1 this indicates the presence of another nourishing component of bread4 ,certain kinds of bread are supposed to contain no free starch1 because this substance is not beneficial to some people4 ,iodine again will reveal whether the bread is as it is described1 for1 if there be no free starch there will be no blue colouration4 ,brown bread will show much more of the yellow colouration and less of the blue than white bread4 ,good1 well-baked bread should keep for a considerable period without turning sour2 we can easily see whether our sample is satisfactory by running a drop of litmus on to it and watching the effect under the microscope2 if the litmus remains unchanged in colour the sample is not sour2 if1 on the other hand1 the litmus turns red it shows us that acid is present and that our bread is not as it should be4 ,tea is difficult to prepare for microscopic examination and most of the tests call for expert knowledge1 not only in the management of the microscope but of the plant itself4 ,the structure of the leaves can be made out clearly in specimens which have been soaked for a time in water1 but this is of little interest to the ordinary microscopist4 ,one very pretty test may1 however1 easily be performed4 ,we all know that it is not good to drink tea which has been standing for a long time4 ,some tea-drinkers are so particular that they cannot bear to see the teapot shaken before they have poured out their cup4 ,all this trouble arises because tea contains a poison called 8theine02 it is an alkaloid1 one of a large class of chemical substances which are nearly all deadly poisons--cocaine and nicotine are alkaloids4 ,although theine is poisonous1 tea which contained none of this substance would be tasteless and the absence of this substance shows that the tea leaves have been badly prepared4 ,tea after being gathered should be dried at once1 sometimes it is re-dried and this process drives off the theine4 ,for our test we require1 in addition to our microscope1 two watch glasses1 a piece of copper wire gauze and a gas burner or a spirit lamp4 ,place a little tea in one of the watch glasses and cover with the other watch glass2 then heat gently on the wire gauze4 ,in a few minutes drops of moisture will appear on the upper watch glass2 after about ten minutes' heating beautiful1 long1 needle-shaped crystals will begin to appear1 with a little further heating we shall obtain a good crop of lovely crystals on the upper watch glass and they make a splendid object for examination under a low magnification4 ,the crystals are of theine1 the poisonous component of tea1 and the test is used to discover whether the tea has been redried during its preparation2 redried tea gives no crystals4 ,illustration3 ,photos by ,flatters ,garnett ,,the ,,stinging ,,hairs ,,of ,a ,,nettle ,these hairs are much longer than ordinary plant hairs4 ,sharply pointed at one end1 there are sacs at their bases containing acid4 ,,butterfly ,,wing ,,scales ,scales from the wing of a butterfly4 ,each scale is a hollow sac1 affixed by its notched end to a pit in the insect's wing4 ,the examination of cocoa for impurities is a matter rather for the chemist than for the microscopist4 ,it contains a vast number of starch grains1 not unlike those of rice1 except that they are rounded4 ,coffee often contains a number of impurities1 the chief being chicory1 various starches1 ground acorns and date stones4 ,chicory is really an impurity1 though it is one often asked for by coffee-drinkers4 ,it is easy to detect the amount of chicory present in a sample of ground coffee1 by throwing a little of the mixture on to water4 ,the chicory sinks at once1 whereas the coffee floats for a while because it is oily4 ,in pure coffee there should be no starch and the iodine test will readily show whether we are dealing with a sample free from starch or not4 ,mustard is very rarely purposely mixed with any impurities1 in fact it is probably the least likely to be adulterated of any article of food4 ,under the microscope a large number of small objects1 very similar to starch grains1 can be seen4 ,they are the cells containing mustard oil and they are not stained blue by iodine4 ,a specimen of pure mustard contains no starch4 ,pepper is by no means easy to test for impurities4 ,it contains minute starch grains1 which can be recognised under the microscope after staining4 ,it is mentioned here because of a very interesting and easily performed experiment that will appeal to every microscopist4 ,place a little pepper on a clean slide and moisten it with a drop of alcohol1 allow it to stand for a minute or so then add a little dilute glycerine1 cover the specimen with a cover glass and examine it under the microscope after the lapse of about five minutes4 ,the sight of wonderful prismatic crystals forming one by one in rapid succession will be ample reward for the trouble taken4 ,a drop of strong nitric acid1 which must not be allowed to come in contact with any part of the microscope or with one's hands or clothes1 will turn the crystals a rich orange colour4 ,the crystals are composed of a substance called piperine4 ,everyone knows of the importance of pure water for drinking purposes but the word pure in this case is used in a very wide sense1 for the only really pure water is distilled water and it would not form a very good beverage4 ,although ordinary tap water may contain a number of impurities it is not easy to see them without taking a little trouble4 ,if our tap water is so contaminated that a drop1 examined at random1 shows us all manner of solid matter floating in the water there must be something seriously wrong4 ,those who are engaged in testing water under the microscope1 first take a big jug full of the water and allow it to stand for twenty-four hours1 covering it the while to keep out dust4 ,at the end of this time most of the water is carefully drawn off1 from the top1 with a siphon and the remainder1 after stirring is poured into a conical glass and allowed to stand for a further twelve hours4 ,then the upper portion of the water is again siphoned off and a little of the remainder1 which is left in the point of the conical glass is drawn by suction into a special kind of glass tube1 called a pipette4 ,this final sample contains all the solid matter which settles to the bottom of the water after standing for thirty-six hours4 ,the impurities likely to be present in water make such a formidable list that we can only mention a small number4 ,there may be various mineral substances1 such as lime1 sand or clay2 vegetable substances1 starch grains1 fragments of wood1 pieces of decayed leaves and the like or there may be hair1 scales of fish1 etc4 ,the impurities may be living plants1 of which the most likely to be found are bacteria1 diatoms1 desmids and ,volvox1 amongst plants1 and rotifers1 ,vorticella1 ,paramcium1 ,amba1 also portions of tapeworms and their eggs amongst animals4 ,these creatures are all described elsewhere so we need not dwell on their peculiarities here4 ,in addition to all of the above and many more not mentioned there are four metals commonly found in impure water1 either in small solid particles1 or in the form of one of their compounds soluble in water4 ,the metals are iron1 copper1 zinc and lead4 ,very simple chemical tests will show whether they are present or not4 ,to a drop of the water add a very minute quantity of hydrochloric acid and of potassium ferrocyanide solution4 ,when iron is present the solution will turn blue2 in the presence of copper it will become bronze coloured1 whilst zinc turns it a milky white4 ,to detect lead1 take another drop of water and add a very small quantity of potassium chromate solution4 ,if the suspected impurity is present the solution turns yellow4 ,all the chemicals for these simple tests may be obtained at any chemists and there is this great advantage in testing under the microscope--only very small quantities are required4 ,butter can hardly be described as an interesting object for the microscope1 nevertheless1 it may be of use to explain the methods of its examination4 ,a small sample should be placed upon a clean slide1 a drop of olive oil added and the whole covered with a cover slip which may be pressed firmly till the specimen forms but a thin layer4 ,of course the most important impurities likely to be present are bacteria but these we cannot see without special preparation and we are not dealing with bacteria in the present chapter4 ,if our specimen is in a film sufficiently thin to be transparent1 and we should have made it so by pressure on the cover slip1 we may first of all examine it carefully for starch grains which1 by the way1 should be absent4 ,the amount and size of the drops of water1 which every butter sample contains1 are of importance in deciding its quality4 ,in good butter there are a few scattered drops of various sizes2 in milk-blended butter the water globules are all very small and all of the same size1 or as nearly so as the eye can judge2 in butter containing an excessive amount of water the drops appear large1 much larger than in a normal sample4 ,if we examine various samples1 we shall find that some are much more transparent than others1 the transparent samples being fresh butter4 ,the curd also in fresh samples is much more finely and evenly scattered in the field of view than in older samples4 ,renovated butter1 that is to say rancid butter which has been melted and made palatable by forcing steam through it1 should be examined by oblique light--easily arranged by tilting the mirror at an angle--when the curd appears as white patches on a dark background4 ,it is curious that one article of food1 honey1 is more likely to be pure when it contains impurities4 ,this sounds like a bull but a great deal of honey is manufactured from various sugars but not by bees4 ,this artificial honey contains no pollen grains1 in fact any honey found to be free of pollen should be looked upon with suspicion4 ,starch often occurs in artificial honey1 never in real bee-made honey4 ,to many foods adulterants are added as preservatives1 the nature and quantity of such additions is settled by ,act of ,parliament4 ,many foods are preserved with small quantities of ,borax or ,boric ,acid4 ,the use of ,formaldehyde1 formerly sold under the ,german trade name of ,formalin1 is not unknown but it is very injurious4 ,salicylic ,acid which was formerly much used is being supplanted by ,benzoic ,acid1 for the reason that the latter is not so easily detected and therefore prosecution for excessive quantities is not so likely to follow4 ,these preservatives are not easily detected by the microscopist unless he be a chemist also4 ,as we have already remarked adulterants are added for the sake of colour1 either because the public demand certain colours1 or to hide fraud4 ,milk for instance1 when watered1 assumes a characteristic blue colour2 to hide the blue shade various dyes1 anetto1 turmeric or carrot juice are added or one of the aniline dyes1 products of coal tar4 ,this form of deception became so common that now the public demand yellow milk and butter4 ,jams made from inferior or over-ripe fruit are frequently coloured with coal tar dyes1 so also are cheap sweets4 ,oxide of iron is added to potted meats1 sauces1 etc41 to improve their appearance4 ,bottled peas1 which if untreated would be of a yellowish-green colour1 are made to appear bright green by the addition of the poisonous blue vitriol2 fortunately this chemical unites with the chlorophyll of the peas to form a compound which is insoluble in the human body and so no great harm is done4 ,we may compare the chlorophyll in a healthy1 undoctored green pea with that in a pea which has been treated with blue vitriol2 under the microscope we shall notice the striking difference between the two4 ,when we admire the beautiful crystals which go to the making of a piece of lump sugar we little dream that1 if those crystals were pure they would be yellow4 ,the housewife1 however1 demands her lump sugar white so ultramarine is added to mask the yellow colour and give the sugar its white appearance4 ,most of these impurities are difficult or impossible of detection under the microscope2 they are added to give the food a more pleasing appearance in the first place1 for there are undoubtedly certain people who prefer to consume food which appeals to the eye1 though of doubtful purity1 rather than unadulterated though perfectly pure fare4 ,when added solely for the sake of appearance it matters little1 but the habit of making these additions is frequently cultivated to hide bad material and imperfections in manufacture4 ,sometimes adulterants find their way by accident into our food4 ,a good many years ago numbers of people were poisoned by drinking beer1 in some cases with fatal results4 ,tests were made and the beer was found to contain arsenic but how it got there remained a mystery4 ,at length the glucose1 a kind of sugar used in making beer and added also to a good many of our foods1 was found to contain the substance4 ,now in the making of glucose1 sulphuric acid is used and in this particular case the impure or commercial acid had been taken4 ,this impure acid frequently contains arsenic and1 in the case we mention1 the results of its use were disastrous4 ,,chapter ,,xi ,,bacteria ,there is probably no scientific work more wedded to the microscope than the study of bacteria4 ,we may learn a great deal about birds or insects or rocks or minerals1 without any instrument but we can learn little of the bacteria unless they are highly magnified4 ,there is such an extraordinary amount of misconception concerning bacteria that1 it will be time well spent if we attempt to clear up all misunderstanding at the start4 ,bacteria1 often called microbes or germs1 are looked upon with considerable awe by most people1 who associate them in some vague way with disease4 ,there is no denying that many bacteria are responsible for certain diseases2 many more are perfectly harmless and a goodly number are exceedingly useful4 ,to enumerate all the bacterial activities would require a large book but briefly1 apart from the disease-causing bacteria1 they enter into the manufacture of cheese and butter1 of wine and vinegar2 they are essential to brewing and tanning2 they act as scavengers over the face of the earth1 breaking up a mass of decaying animal and vegetable matter into simple chemical substances which can then be used again as food for plants2 some of them also can take a gas called nitrogen1 from the air1 and pass it on to green plants4 ,what are these active little creatures8 ,the question is a natural one4 ,they are merely very minute1 one-celled plants4 ,each one possesses a firm cell-wall1 filled with living matter2 in an earlier chapter1 we described the one called protean animalcule and1 although it was composed of but a single cell it had no definite wall4 ,this is one of the essential differences between plants and animals1 both of them are made up of one or more1 maybe millions of cells1 but each plant cell is surrounded by a well-defined wall1 animal cells have no such walls4 ,the exact position of the bacteria in the plant world is still open to doubt4 ,most scientists place them amongst the fungi2 for1 with very few exceptions they possess no chlorophyll4 ,one or two of them1 however1 do possess a green colouring matter which1 if not chlorophyll is very near to it2 on this account other scientists are of the opinion that they are related to the seaweeds4 ,it is a matter1 however1 that does not concern us very deeply1 for our purpose it is sufficient to know that they are plants4 ,when they were discovered1 nearly three hundred and twenty-five years ago1 they were looked upon as minute animals and it is curious that the belief has survived this long period of time in the popular mind4 ,long before the activities of bacteria were connected with various phenomena1 such as infectious diseases1 souring of milk1 etc41 it was thought that these changes were brought about by chemical action4 ,like many of the early theories1 this one contained a half truth1 for a great many of the changes brought about by bacteria are really due to chemical action initiated by the organisms4 ,in other words1 the bacteria set free certain substances which actually cause the changes to take place4 ,let us make our statement clear by a simple experiment4 ,to a little fresh milk we add a weak acid1 the milk curdles at once and by dipping a piece of litmus paper 7obtained at any chemist's7 into the mixture1 it will turn red1 showing the presence of acid4 ,litmus1 by the way1 is obtained from a lichen2 in the presence of acid it is red1 an alkali1 the opposite of an acid1 turns it blue4 ,in a neutral solution1 that is to say one that is neither acid nor alkaline1 litmus is of a purplish hue4 ,to continue our experiment1 we allow another sample of the same milk to stand for a day or two in a warm1 dark place and again the milk will be curdled4 ,a test with the litmus will show that the solution is acid4 ,the bacteria themselves have not curdled the milk but they have liberated a substance1 called a ferment1 which has split up part of the milk into an acid1 amongst other things and that acid has actually done the curdling4 ,for this reason1 weak alkalies are sometimes added to milk4 ,acids and alkalies1 of equal strength form neutral solutions1 so that1 when the milk bacteria begin their activities which result in the formation of acid1 it is at once made neutral by the alkali4 ,by this means1 curdling is postponed for a little while1 though there comes a time1 of course1 when all the alkali is used up1 then the acid gains the upper hand and curdling takes place4 ,we could if we wished continue adding more and more alkali to keep pace with the formation of acid1 but too much alkali would be as unpalatable as too much acid1 so nothing would be gained4 ,before we bring out our microscope to examine these lowly plants1 we will first of all kill a myth which has survived1 in the non-scientific mind1 since the eighteenth century and then describe briefly the life history of a typical bacterium4 ,now for the myth4 ,bacteria are so minute1 their activities so great and the results of their activities so far reaching1 that it is hardly surprising to learn that1 even at the present day1 bacteria are supposed simply 8to happen40 ,we talk of thunder turning milk sour1 but thunder can no more sour milk than can a passing train or an air raid or a burst in a water main4 ,true1 milk turns sour more quickly in thundery weather than in frosty weather1 because1 when thunder threatens1 the air is warm and the milk-souring bacteria increase more rapidly in warm weather than in cold4 ,we must remember always that bacteria are living beings and in common with all other living things they must have parents4 ,what probably took place at the beginning of the world we cannot consider here but one thing is certain that1 at the present day1 no living matter is produced from non-living matter2 8life from life0 is the only theory that will stand scientific tests and this has been the case ever since the simplest microscopes were thought of and thousands of years before that4 ,any substance1 however liable to decay1 if rendered germ free and kept germ free1 will retain its fresh condition indefinitely4 ,could bacteria or germs1 call them what you will1 simply happen it would be useless attempting to fight against them4 ,bacteria are everywhere4 ,in the water we drink1 in the milk1 butter1 cheese and in dust4 ,we cannot avoid them1 try as we will2 it is fortunate1 therefore1 that the majority are harmless4 ,you may be surprised that1 with this ubiquity1 you have never seen one4 ,when1 however1 you learn that most of them are only about twenty-five thousandths of an inch long and that a thousand million of them could be packed comfortably into a little box1 whose sides measured but a twenty-fifth of an inch in length1 it is not really so surprising after all4 ,being so small1 the activities of a single bacterium are insignificant2 that 8union is strength0 was never better exemplified than amongst these lowly plants4 ,there are no male and female bacteria1 in the majority of cases they increase by splitting1 in fact they are often called splitting plants4 ,the change may be watched under the microscope4 ,the plant elongates somewhat1 it becomes narrower and narrower in the middle1 it develops a waist in fact2 finally the two halves part company and each one leads a separate existence as a bacterium4 ,this splitting progresses at an extraordinary rate4 ,a celebrated scientist once wrote3 8,let us assume that a microbe divides into two within an hour1 these two into four in the next hour1 these again into eight in the third hour and so on4 ,the number of microbes thus produced in #bd hours would exceed #af-a_/b millions2 in two days they would increase to #dg trillions1 and in a week the number expressing them would be made up of #ea figures4 ,at the end of a day 7#bd hours7 the microbes descended from a single individual would occupy one fortieth of a hollow cube with edges one twenty-fifth of an inch long1 but at the end of the following day would fill a space of twenty-seven cubic inches1 and in less than five days their volume would equal that of the ocean40 ,it is hardly necessary to add that these alarming figures represent what would happen if no accident befell the bacteria1 they show the enormous vitality possessed by the smallest of all plants4 ,even allowing for misadventure their increase is alarming2 actual tests1 with a sample of milk containing originally #aec1jjj bacteria per cubic inch1 show that the cubic inch contained after one hour1 #eci1gej2 after two hours1 #faf1bej2 after seven hours1 #a1jbj1jjj2 after nine hours #b1jdj1jjj and after #be hours #he1jjj1jjj individuals4 ,the writer whom we have just quoted calculated that a single bacterium weighs about #j4jjj1jjj1jjj1jbd1bdc1fgb of a grain1 that forty thousand millions weigh one grain and that two hundred and eighty-nine billions weigh a pound4 ,the descendants of one bacterium weigh #a_/bfff of a grain1 after twenty-four hours2 more than a pound after two days1 and sixteen and a half million pounds after three days4 ,the assumption in this case1 also1 is that no harm comes to any of them2 the mortality amongst bacteria is1 clearly1 very great4 ,sometimes1 owing to external conditions1 such as lack of food certain bacteria produce spores4 ,the power of spore formation is not possessed by all bacteria and those which are able to bring it about are difficult to kill for the spores1 which contain the living material of the bacterium are surrounded with walls which will resist boiling1 drying1 freezing and all manner of ill treatment4 ,the spore formation of bacteria is very simple1 all or part of the living contents of the bacterium becomes surrounded by a tough wall and remains so surrounded till circumstances are favourable1 when the wall bursts1 its contents escapes and becomes a bacterium1 capable of founding a new colony by the method of splitting we have already described4 ,now let us try to find out what sort of plants we are to look for1 when we are searching for bacteria1 under our microscope4 ,they exist in many forms1 to which special names have been applied1 and it is unfortunate that1 very often1 their external form varies according to their state1 thus a bacterium may be spherical when young and rod shaped when older4 ,some bacteria are spherical and are known as ,cocci or ,micrococci1 from ,greek words meaning a berry or a little berry respectively2 sometimes these spherical bacteria occur in pairs1 then they are called ,diplococci 7double berries72 or in chains1 ,streptococci 7chain berries72 or in bunches1 ,staphylococci 7grape berries74 ,they may resemble short rods1 when they are called ,bacteria1 a name1 by the way1 which is also applied generally to all microbes2 they may1 on the other hand1 have the appearance of longer rods and then they are called ,bacilli4 ,some of these longer rods may be curved or even corkscrew shaped when they are known by the name of ,spirilla4 ,rather fearsome names some of these we fear and we wished to avoid long names1 but they appear over and over again in books and papers relating to bacteria so we are compelled to introduce them to our pages4 ,many bacteria possess no power of movement1 others swim rapidly1 by the aid of the lashing movement of little whip-like structures with which they are furnished4 ,after all this preamble1 which we hope has cleared up certain misconceptions regarding bacteria and has given the reader some insight into their habits1 we may proceed to the examination of some of the plants themselves4 ,at the outset we have a confession to make4 ,bacteria can only be studied seriously1 by those who possess very expensive and elaborate apparatus2 considerable technical skill is required to prepare the plants for examination--many of them indeed can only be seen after they have been stained and lastly1 to trifle with the disease-causing members of the family may lead to dangerous if not fatal results4 ,having issued our warning let us see what we can do in the way of microscopic investigation4 ,the easiest subject with which to make a start is the ,hay ,bacillus1 ,bacillus ,subtilis1 not because it is the largest of the bacteria by any means1 but because it is very easily obtained4 ,each plant measures about five thousandths of an inch in length1 so we shall require a high magnification to examine it4 ,having obtained a small quantity of hay1 we must boil it in water for about three-quarters of an hour and then set it aside for some hours4 ,in due course the water will contain hundreds upon hundreds of bacteria or1 speaking more correctly1 of bacilli4 ,for our work1 we shall require a special kind of microscope slide2 instead of the piece of plain glass we have been accustomed to use we must obtain one with a circular portion1 hollowed out from the centre4 ,having done so1 we take a clean glass rod and1 with it1 transfer a drop of the water1 containing the bacilli1 to the centre of a clean coverslip4 ,invert the coverslip so that the drop is on the lower surface and place it over the hollow portion of the slide1 in such a manner that the drop still remains suspended from the coverslip2 this is known as the hanging-drop method and requires some little skill to accomplish satisfactorily4 ,when our slide is prepared1 with a magnification of at least one thousand diameters1 we may reasonably hope that our trouble will be rewarded4 ,at first we shall probably see nothing4 ,we recall that we had some difficulty in examining starch grains1 on account of the fact that they were colourless4 ,this time we are dealing with a far more difficult subject4 ,when our eyes become accustomed to the light1 however1 we shall be conscious that there is something moving in our drop of water4 ,the ,hay ,bacillus is one of the moving forms1 each individual is furnished with a number of little whips whose lashings enable it to travel through the water4 ,the whips cannot be seen in unstained bacilli2 experience1 however1 tells us that they are there1 for all these lowly plants which show movement are seen when stained1 to possess the little whips4 ,the process of staining kills the plants so that we cannot see the little whips in action4 ,having detected that movement is taking place1 a little adjustment of focus and a further search will reveal the bacilli to us1 as little rod-like1 colourless individuals4 ,we shall see their cell contents if they are sufficiently highly magnified and also their cell walls4 ,we may even observe them splitting1 each one into two individuals4 ,we must keep our sample of water for later examination4 ,in fact1 we may examine drops from day to day1 in exactly the same manner4 ,after a short lapse of time we shall notice that the bacteria have increased to an alarming extent and also that they no longer swim about4 ,at this period they tend to arrange themselves in chains lengthwise1 their cell walls also lose their clear cut appearance and become jelly like1 yet withal they may still continue to split up4 ,if we now examine the water from which we have taken our drop we shall probably find a scum floating on the surface2 it consists of millions upon millions of hay bacilli1 huddled together so to speak4 ,it is the beginning of the end for them1 nourishment is becoming scarce and important changes are about to take place4 ,let us continue our examination day by day1 that we may discover what is happening4 ,before long1 we shall find that within each cell wall1 which is no longer jelly like1 there is a darker cell contents than we saw before4 ,the bacilli have1 in fact1 formed spores4 ,now we may plug our bottle containing the remainder of the water1 with cotton wool and set it aside for some months if we wish4 ,at the end of that time1 by pouring a fresh supply of water upon the spores1 we may start them all into a new vitality and the whole process will be repeated4 ,we have mentioned that bacteria should be stained1 in order to make their presence more easily detected4 ,this is hardly the place to enter into a lengthy discussion concerning the methods of staining but1 for the benefit of our readers1 who wish to pursue the subject further1 we will state as concisely as possible how simple staining may be accomplished4 ,our requirements are1 a pair of ,cornet's forceps1 two small bottles of stain1 say ,carbol-,fuchsin and ,methylene ,blue and a larger bottle of #a_/b per cent4 ,acetic acid2 these may be obtained from the firm who supplied our microscope and1 for the beginner at anyrate1 it is cheaper to buy the solutions ready made1 than to attempt to make them up at home4 ,slides and cover slips1 we require1 of course1 and they must be absolutely grease proof2 it may be necessary to boil them in a strong solution of caustic soda to effect this result4 ,a small bottle of ,canada ,balsam completes our requirements4 ,should we wish to examine a drop of milk for bacteria1 we proceed in this manner4 ,with the aid of the ,cornet's forceps pick up two cover slips1 place a drop of milk on one and cover with the other4 ,with thumb and finger bring the glasses into close contact1 so that the milk forms a thin film4 ,slide one glass from the other and set aside1 milk side upwards1 till dry4 ,next take each cover slip1 separately1 in the forceps and pass rapidly two or three times through the flame of a spirit lamp1 this fixes the bacteria1 if any be present1 to the glass4 ,now having poured a little of the stain1 say methylene blue1 into a shallow vessel1 a saucer will do1 we place our cover slips therein for two minutes or so4 ,then1 remove them with the forceps1 wash in water till no more stain comes away and set aside to dry4 ,when dry1 take a clean slide1 place a small drop of ,canada ,balsam at its centre and gently lower the cover slip thereon1 stained side downwards4 ,if we now examine our slide under a high magnification1 we shall easily be able to see whether bacteria are present or not4 ,should our preparation be too deeply stained1 a good slide will show the bacteria stained blue against an almost colourless background1 we must immerse our second preparation for a few moments in a little of the #a_/b per cent4 acetic acid which will have the effect of removing the excess of stain2 then1 after washing and drying1 we proceed as before4 ,beautiful double staining may be performed by the following method4 ,in addition to the chemicals we already possess we shall require some #e per cent4 acetic acid4 ,double staining is especially useful for spore-forming bacteria1 so we may take some of the ,hay ,bacillus at sporing time4 ,proceed exactly as described above substituting1 of course1 a drop of water known to contain the bacilli for the drop of milk4 ,when the two cover slips are ready for staining1 warm some of the ,carbol-,fuchsin in a saucer and leave the cover slip therein for five minutes1 then transfer to a #e per cent4 solution of ,acetic ,acid till all the stain appears to be removed1 afterwards wash in water4 ,the cover slips must next be immersed for a few minutes1 two should be long enough1 in ,methylene blue solution1 then washed and1 when dry1 mounted on a slide with ,canada ,balsam1 as described above4 ,if the staining has been properly carried out1 we shall have a most beautiful preparation1 showing spores stained red and the rest of the bacilli blue4 ,the work that may be done with bacteria is limitless but1 to advance very far1 we shall need facilities for obtaining what are known as 8pure cultures40 ,let us make the term clear4 ,suppose we take milk1 water1 butter1 anything in fact upon which bacteria will grow and examine them carefully4 ,if we have the requisite knowledge and recognise what we see1 we shall find not one kind of bacterium but a number of different bacteria4 ,now by certain manipulations1 which need not be described here1 all the different kinds of bacteria may be sorted out1 so that we have colonies consisting of one kind of bacterium only and such a colony is known as a 8pure culture40 ,in practice1 bacteriologists do not use the rough and ready methods that we used in dealing with the ,hay ,bacillus4 ,they prepare pure cultures and cultivate the bacteria on various substances1 differing markedly from those on which they originally lived4 ,for example1 a jelly-like substance1 mainly composed of beef broth and gelatine is one of the favourite substances on which to grow bacteria1 milk is also used in some cases and also slices of potato4 ,all this may seem to have little to do with the microscope1 but indeed the bacteriologist relies as much on the behaviour of his pure cultures1 growing on gelatine1 etc41 as on their appearance under the microscope4 ,some bacteria will not grow on the surface of the gelatine but only in the body of the substance1 where air cannot reach them2 others cause the gelatine to become liquid2 others give off a characteristic smell or impart a well-marked colour to their food material2 a few even cause the gelatine to become luminous4 ,these easily seen characters are quite as typical of the various bacteria which bring them about as are the microscopic characters2 in fact it sometimes happens that only by a combination of the two is it possible to be certain of what one has obtained4 ,,chapter ,,xii ,,medical ,,work ,,with ,,the ,,microscope ,to the medical man1 a microscope is all important4 ,in the first place it is absolutely necessary for him to have an accurate knowledge of the human body2 he must be able to recognise healthy blood1 he must know the varied cells composing muscle and bone1 etc4 ,then again the medical aspect of bacteriology is all important2 we have devoted a separate chapter to bacteria and there we warned our readers not to look upon all bacteria as harmful1 nevertheless1 the harmful ones are all important in medical work4 ,of recent years a knowledge of the structure and habits of certain insects has become an important branch of medicine for many of these creatures carry diseases from one patient to another4 ,this branch of medicine is more important in the tropics than in this country1 for most of the really harmful insects live in warm countries4 ,a number of lowly animals claim attention from the medical man for they are parasites of the human body2 many fungi1 too1 cause disease4 ,a certain amount of chemical work with the microscope also falls to the lot of the medical man4 ,we have stated many times in our pages that1 both plants and animals1 are made up of one or more cells and that the cells of plants are each surrounded by a more or less rigid cell wall1 whilst those of animals have no definite cell wall4 ,as a start in our medical investigations we may examine some cells from our own person4 ,there is no need for alarm1 the operation is quite painless4 ,after having prepared our microscope and got ready a clean slide1 on which we place a drop of clean water1 we must take some clean1 blunt instrument such as a tooth-brush handle and gently scrape the inside of the cheek4 ,having done so1 dip the part of the tooth-brush with which the scraping has been done1 in the drop of water1 then cover the water with a cover slip4 ,a careful examination of our object with a fairly high magnification will show that1 though the scraping was very gentle and quite painless1 something has been removed from the mouth4 ,we shall see a number of cells1 somewhat overlapping like the tiles of a roof4 ,they are almost colourless1 and have ill-defined margins1 certainly no cell wall1 and each cell contains a dark spot near its centre4 ,these cells from our own person will give us a good idea of the appearance of animal cells1 for we are animals1 much as we may dislike the idea4 ,the dark spot in the middle of each cell is called a nucleus1 it is the most active part of the cell and when the latter is about to divide1 as it does when growth takes place1 the nucleus always divides first4 ,illustration3 #a4 ,,crystals ,,from ,,human ,,blood ,it is often possible to identify the source of blood by means of crystals which can be obtained from it1 for each race of animal has its own special form of blood crystal4 ,the large crystal at the margin exhibits the typical shape4 #b4 ,,crystals ,,from ,,the ,,blood ,,of ,,the ,,baboon ,these show some resemblance to human blood4 ,now we may perform another operation upon ourselves1 rather more painful than the last one but not very serious4 ,we wish to examine some human blood1 so we tie a handkerchief tightly round one of our fingers and with a clean needle--be sure that it is clean--make a puncture in the finger tip4 ,the handkerchief bandage will prevent our feeling any pain4 ,we must put the drop of blood we have obtained in the centre of a clean slide and examine it under the microscope4 ,while the blood is still liquid1 we shall see a number of circular discs floating about1 they are very small being only #a_/cbjj inch in diameter4 ,the centre of each disc appears darker than the rim1 but this darker shade is only apparent4 ,using a term we introduced in our chapter on the lens1 we may call the discs double concave4 ,now let us watch our objects for a moment and we shall notice that they begin to arrange themselves in chains1 they appear like a number of draughtsmen placed one upon the other1 our drop of blood is now beginning to clot4 ,a simple experiment may be attempted at this stage2 we must run a drop of water on to our little blood discs and watch carefully what happens4 ,we shall see that they change their shape gradually1 from being double concave they become flat sided1 and this is not all1 for they continue to change till both sides bulge outwards and they may be described as double convex4 ,these little discs are known as red blood corpuscles4 ,their shape is some indication of the animal to which they belong2 those of man1 as we have seen1 are circular and so are those of most of the higher animals1 except the camel tribe1 which has oval1 red blood corpuscles4 ,birds1 reptiles and fishes have corpuscles agreeing in shape with those of the camel4 ,in size there is a great deal of difference between the corpuscles of various animals2 a member of the deer family has the smallest and a creature related to our ,newts1 called ,proteus1 has the largest4 ,the size of the blood corpuscles bears no relation to the size of the animal to which they belong1 those of the frog measure #a_/aajh inch1 or nearly three times the size of the red blood corpuscles of man4 ,without much difficulty it should be possible to obtain other samples of blood and the red corpuscles should always be examined1 needless to say the blood should always be in a fresh condition4 ,in addition to the red corpuscles we may notice a few smaller circular bodies1 they are the white corpuscles4 ,if we have any difficulty in finding them in our own blood1 we can examine another specimen of frog's blood1 in which they are more easily seen4 ,it has been calculated that in a cubic inch of blood from a healthy human being there are eighty millions of red and a quarter of a million of white blood corpuscles4 ,although there is such an enormous difference in the sizes of red corpuscles from various animals1 the white corpuscles are remarkably constant1 measuring about #a_/cjjj inch in warm-blooded animals and #a_/bejj inch in reptiles4 ,sometimes1 as we are examining the white blood corpuscles under the microscope1 we shall notice that they behave in a similar manner to the ,proteus ,animalcule1 which we described in our chapter on ,pond ,life4 ,a kind of creeping motion takes place and the corpuscle loses its circular shape4 ,in our own blood this movement lasts but a very few moments1 in frogs' blood1 by keeping our slide moderately warm1 we may witness the movement for some time4 ,it is perfectly easy to watch the circulation of blood in the foot of a frog4 ,for this purpose we require a piece of apparatus known as a frog plate1 this is merely a flat brass plate perforated with a number of holes1 through which tape is passed to bind the frog down and having also a hole the size of the opening in the microscope stage1 into which a circle of glass is usually fitted4 ,such a plate may be made of wood and will serve our purpose quite as well as the more expensive brass plate4 ,we must bind our frog firmly1 but not too tightly with wet rag1 leaving one leg exposed4 ,this free leg must now be fastened in such a manner that one of the webs between its toes comes over the opening in the plate1 finally the toes must be carefully tied with string so that they remain apart and the web is fully expanded4 ,having fixed our frog in a satisfactory position let us examine his blood-vessels under a fairly high power4 ,we shall find that there are large and small vessels in his webbed foot2 we will devote our observation to the small vessels1 called capillaries1 from the ,latin ,capillus1 a hair1 because of their small size4 ,probably the blood will not flow when we make our first examination and this points to one of two things1 either the frog is bound too tightly or he has not recovered from the alarm he experienced at his treatment4 ,in the latter event he will not be long recovering and his blood circulation will soon be in full working order2 in the former case1 we must loosen his bandages4 ,in some of the very small blood-vessels we shall notice that the blood always flows in one direction1 in others it does not appear to have any definite direction4 ,in either case1 however1 we can see the red corpuscles flowing rapidly along the central stream of the blood-vessel whilst the white corpuscles travel much more slowly along the sides4 ,the medical man may be called upon to decide two questions concerning human blood2 he may wish to know whether it is healthy and1 in the case of certain crimes1 he must be able to state positively whether certain stains are caused by human blood or not4 ,dealing with these questions in order1 let us see how we would proceed4 ,there are many people1 far too many in towns who are described as bloodless1 the expression is of course an exaggeration for no bloodless person could continue to exist4 ,what really happens is that such people are deficient in red blood corpuscles4 ,if we examine two samples of blood1 one from a perfectly healthy subject and one from a so-called bloodless subject we shall probably not be able to detect any difference between the two1 but the experienced medical man will soon see that one sample has too few red blood corpuscles4 ,an unhealthy state of the blood is often indicated by the shape of the blood crystals4 ,let us see how we may obtain some of these crystals4 ,if we add a drop of ether to our drop of blood upon the slide1 and wait a few moments till the ether has evaporated1 we shall notice when we examine our object again1 under a high magnification1 that a number of prismatic crystals have formed1 especially towards the edges of the slide4 ,now in certain diseases of the blood1 these crystals are no longer formed in their usual shape1 thus pointing out to the medical man that something is amiss4 ,again there are many blood parasites just as there are external parasites of man4 ,in the disease known as malaria1 very small parasites are introduced into the blood by mosquitoes4 ,each of these little parasites enters a red blood corpuscle1 divides up into many smaller individuals1 causes the corpuscles to burst1 then each little parasite attacks more corpuscles4 ,some of these little bodies are sucked up1 along with the blood of malaria patients1 by other mosquitoes and1 if the insects are of the particular kind which spread malaria1 the parasites complete their development within the mosquito4 ,patients suffering from that terrible ,african malady known as sleeping sickness1 have blood parasites resembling minute eels with long threadlike tails4 ,these parasites are the cause of the malady and are introduced into the blood by flies1 closely related to house flies4 ,there are a very large number of blood parasites of one kind and another1 so it is clear that a knowledge of blood is very important to the medical man4 ,from our remarks concerning the sizes of the red corpuscles in the blood of man and various animals1 one might be excused from thinking that it would be quite easy for anyone with a little experience to recognise human blood4 ,as a matter of fact it is very difficult1 it is always a doubtful matter to rely upon size alone4 ,we have mentioned blood crystals and these give us a slightly better clue to the origin of the blood1 for the blood crystals of different animals vary in shape1 far more than their corpuscles4 ,those of the guinea-pig1 for example1 are little four sided pyramids2 those of the mouse1 eight sided and so on4 ,some apes1 however1 have blood crystals very similar to those of man1 so similar that the two may be confused4 ,the microscopist who is compelled to give an opinion concerning the origin of a sample of blood1 especially blood which is some days old1 is faced with no light task4 ,without the assistance of the microscope1 medical men would never have discovered the cause of many of these insect-borne diseases1 they could never have traced the development of the blood parasites in the bodies of insects4 ,for many years it was thought that the disease malaria was caused by the damp air of low-lying land1 in fact the word malaria is derived from two ,italian words meaning bad air4 ,it was not till the advent of the microscope that the true cause of the disease was learned and the discovery was made that the only connection between the malady and dampness is that the mosquitoes which carry the disease can only thrive in damp situations4 ,medical work with the microscope also entails a study of external and internal parasites of man other than those which infest the blood4 ,some of the larger human parasites we know only too well1 they force their unpleasant attentions upon us from time to time1 but fortunately they are not as a rule serious and are soon got rid of4 ,the cleanest of us1 in these days of universal travel1 cannot avoid the visitations of the lively flea1 he is at worst an annoying companion1 but he has a cousin who is responsible for the passing of the germs of the dreaded plague from rats to man4 ,plague long remained a mystery1 which1 without the help of the microscope1 would probably have remained unsolved to this day4 ,many of these apparently harmless blood-sucking insects may prove to be disease carriers1 as medical knowledge and microscopic investigation is brought to bear upon them4 ,the majority of the smaller external parasites are beyond the reach of the amateur microscopist4 ,a number of course are available to medical students1 but we write for the ordinary enthusiast and not for the specialist4 ,many interesting little mites1 closely allied to the cheese-mites1 cause skin diseases and the creatures themselves as well as their tunnels in the skin are interesting4 ,there is one little parasite which we nearly all of us carry without knowing it1 and it makes quite an interesting object for the microscope4 ,its name is ,demodex ,folliculorum and it dwells in the sweat glands1 especially those round about the nose4 ,it is very minute and requires a high magnification for its examination4 ,the adult is worm-like and tapering in the hinder two-thirds of its body1 whilst the front third1 to which is attached four pairs of short1 fleshy legs1 is stouter4 ,from the eggs which may be heart or spindle shaped1 little six-legged grubs arise2 later these grubs change into the eight-legged adults4 ,all the changes take place in the sweat glands1 and the creatures live with their heads turned away from the gore of the gland4 ,to observe these strange little creatures it is only necessary to squeeze some of the white congealed perspiration from one of these glands on to a slide1 coyer it with a drop of oil or xylol and spread out the object with a needle4 ,by cutting down the light considerably by means of the diaphragm1 we shall be able to distinguish all the stages of these little creatures which1 unbidden1 share our lives4 ,other parasites come to us in our food and1 of these1 one of the most dangerous is known as ,trichinella ,spiralis and gives rise to a disease known as trichinosis4 ,we need not give a precise account of the life history of this interesting worm1 it will suffice for our purpose to know that it finds its way into the bodies of human beings1 in badly cooked pork or in improperly cured ham or bacon4 ,the little worm is only about #a_/be inch long and1 at first1 dwells in the intestines of the pig4 ,each female produces upwards of fifteen thousand young and these pass into the blood of their host and thence to its muscles4 ,snugly coiled into a spiral between the muscle fibres1 each young worm becomes surrounded with a lemon-shaped covering1 which is exceedingly resistant4 ,suppose now a human being should happen to eat such pork1 the juices of the stomach would dissolve the pork and also the little case enclosing the parasite4 ,once set free in the human body1 the whole proceeding is repeated and1 at last1 the result is very severe muscular pains for the victim4 ,the medical man is called upon to study such parasites as ,trichinella1 and they are not so uncommon as one might think4 ,in addition to animal parasites medical science demands a knowledge of many disease bringing fungi4 ,one of the commonest is the fungus responsible for the unpleasant malady called ringworm4 ,but we have written sufficient to show that the general practitioner needs his microscope always by his side4 ,not only so but very many instruments he uses in his work1 though called by other names1 are really microscopes adapted for special purposes4 ,,chapter ,,xiii ,,the ,,microscope ,,and ,,agriculture ,probably there are not many farmers who use a microscope and fewer still who use one to help them in their business1 yet there are few people to whom one of these instruments would be more useful4 ,their seeds are often far from pure and the microscope will reveal the impurities which may consist of dirt and dust1 or of other seeds1 seeds which will grow into weeds and make the crop less valuable or1 if present in large quantities1 render it valueless4 ,agricultural plants become attacked by varied diseases which can only be studied under the microscope2 insects also do their share of destruction and much may be learned about them when they are magnified4 ,fungi and insects not only attack crops but domestic animals as well4 ,the microscope is an invaluable aid in studying the soil1 in dairy work and in many other ways closely connected with agriculture4 ,that the testing of agricultural seeds is very important is shown by the fact that not very long ago a deputation urged the ,government to establish a ,national ,seed ,testing ,station2 no further plans have been made1 however4 ,seed testing is very interesting work1 every seed has its particular shape and markings and the student soon becomes absorbed in seeking for weed seeds among the collections he examines4 ,a weed in the sense we use it here is not necessarily a harmful plant1 it is a plant in the wrong place4 ,for example a carrot growing in a field of turnips1 though a useful plant would be a weed4 ,when the farmer sowed turnip seed he did not do so with the object of raising carrots4 ,the only apparatus necessary for the study of most farm seeds is a powerful magnifying glass1 one that will enlarge the seeds ten diameters or more4 ,when beginning this work1 a difficulty occurs at once for1 without assistance from an expert1 it is by no means easy to learn the names of the seeds one examines4 ,the difficulty can be overcome to a certain extent if we know the names of flowers1 for then we can collect the seeds from these flowers and we shall have properly named specimens as a guide4 ,beginning in this way1 we shall soon find that the seeds can be arranged in groups and there will then be no difficulty in recognising say clover seed or grass seed1 though much more experience will be necessary before we can say to which kind of clover or grass the seed belongs4 ,many of these seeds are well worth studying1 whether we are interested in seed testing or not4 ,the corn buttercup and the wild carrot have curious spined seeds2 those of the larkspur when magnified appear to be studded with little shreds of paper4 ,white and red campion1 have kidney shaped seeds studded with warts and so similar to one another that the microscopist who can distinguish one from the other may consider himself something of an expert4 ,spurrey has lens shaped seeds with raised equator-like rims4 ,evening primrose seeds are curious because they are found in all sorts of shapes4 ,the seeds of rib-wort plantain resemble miniature date seeds1 others resemble minute bananas1 some are perfectly round1 others almost square2 some have smooth shining surfaces which look as though they had been artificially polished1 others again are wrinkled and deeply furrowed2 but1 most curious of all the common seeds are those of the cornflower1 they resemble nothing so much as little shaving-brushes1 with bright yellow bristles4 ,many profitable hours may be spent in studying the seeds of our common native plants1 both wild and cultivated4 ,there are two specially obnoxious plants whose seeds may be mixed with agricultural seed1 to the dismay of the farmer4 ,we refer to ,broomrape and ,dodder1 both of them unable to earn their own living and depending for their existence on the robbing of other plants4 ,broomrape usually attaches itself to the roots of ,hazel1 ,poplar or ,beech and steals its food therefrom1 but its fleshy pink stems and flowers may sometimes be seen in clover fields1 then clover is its victim4 ,more common and more destructive is the little ,dodder1 a member of the ,convolvulus family4 ,its seeds are very minute and when they germinate they give rise to a seedling not unlike a piece of wire4 ,with one end fixed in the ground1 the other waves about till it finds a clover plant round which it twines and not only so but it sends out suckers which microscopic examination shows1 penetrate the stem of the clover to rob its food4 ,by pulling a ,dodder stem away from the clover we can clearly see a number of holes where the suckers have entered4 ,fungus diseases and insects wage constant warfare on the farmer's belongings4 ,that we may better understand the structure of the disease-causing fungi we are about to examine1 let us refresh our memories concerning that very common fungus1 known as white mould and mentioned in an earlier chapter4 ,the reason fungi cause damage to other plants1 the one invariable reason1 is that they1 being unable to manufacture food for themselves1 steal it from the plants on which they grow4 ,some of them are parasites and steal their food from living animals or plants2 others live upon dead animal or vegetable matter and the white mould is one of the latter fungi4 ,in most of the fungi which concern us we shall find that there is a mass of minute1 thread-like structures forming the main body of the fungus and that1 here and there1 portions grow erect and bear spores4 ,the spores1 it is important to remember1 serve the same purpose to the fungus as seeds to the flowering plants4 ,they are blown or carried by insects or other agencies to suitable situations for growth1 they germinate and form new fungi4 ,they are smaller and lighter than the most minute and dust-like seeds1 so that the slightest breeze scatters them far and wide4 ,let us compare the white mould with a mushroom2 at first sight the two plants appear very dissimilar1 in reality they are very similar to one another4 ,the mould forms a thick felt of its threads over the substance on which it grows and mushroom spawn if carefully examined under a microscope will be found to consist of very similar threads1 sealed together to form thicker root-like structures4 ,the fungi1 however1 have no roots and these threads are strictly comparable with those of the mould4 ,here and there the mould sends a single thread into the air and each of these threads is terminated by a little ball which bursts eventually and sets free its contained spores4 ,the same thing occurs with the mushroom2 we have the upright growth1 not of a single thread it is true but of a number1 welded together to form a fleshy stalk2 at the top there is1 not a ball containing spores but an umbrella-shaped structure whose under surface is composed of a number of 8gills0 on which the spores grow at the ends of little stalks4 ,if a piece of the mushroom stem be torn into its separate components and examined under the microscope1 its similarity to the more simple fungus is evident4 ,one of the gills also may be carefully cut away and examined2 the spores will be seen at the end of small forked stalks4 ,having progressed thus far in our study of fungus structure1 we may examine a few of those which cause damage in farm and garden4 ,for the most part1 the thread-like portion of the fungus grows within the plant attacked and only the spore bearing portions appear on the surface4 ,there is one class of fungus1 however1 the ,mildews in which practically all the structure grows on the surface1 only a few small1 unbranched suckers penetrate the plant attacked1 for the purpose of obtaining nourishment4 ,though of great interest to the microscopist1 the potato disease is often the cause of serious loss to the farmer4 ,not only potatoes but also tomatoes are attacked4 ,a potato plant suffering from the disease has irregular yellowish or brownish spots upon its leaves in the summertime4 ,an examination of the lower surface of one of these spotted leaves will reveal a silvery white margin to each spot4 ,this portion should be magnified with a fairly high power and care must be taken not to injure the diseased part of the leaf before it is examined4 ,in cases of serious disease1 from nearly every pore on the surface of the leaf fungus threads will be seen to issue4 ,the threads are branched and1 at the end of each branch1 they have a special kind of spore4 ,they look not unlike miniature leafless trees and they give the typical silvery white appearance to the margins of the diseased spots4 ,when the spores of potato disease germinate1 the young fungus threads enter the leaf through a pore and for sometime afterwards there is no sign that the plant is diseased4 ,on this account potato disease and many other fungus diseases are rendered more serious in that the farmer is not and cannot be aware that his crop is attacked till the disease has taken a firm hold4 ,eventually the potatoes themselves become brown1 rotten and breeding grounds for bacteria4 ,a very common plant disease which makes a good study for the microscope1 may be found in quantity upon shepherd's purse1 and as it also attacks cultivated plants of the same family1 cabbages1 cauliflowers and the like1 it is of no little importance4 ,in its early stages1 the fungus looks like patches of thick white paint upon the plant and where the fungus grows the plant is invariably contorted4 ,as the fungus matures1 the skin of the diseased plant splits and a white powder issues4 ,if some of this powder be highly magnified1 it will be found to consist of chains of spores1 six or seven in a chain4 ,the spores break off singly and each one may start the disease in another plant4 ,the microscopist who hunts in garden and farm for fungus diseases1 will assuredly meet with some examples of that large class known as 8smuts40 ,they are so called on account of the black powder with which the attacked portions of the plants become filled4 ,the smuts are very important but are not of much interest as objects for the microscope1 so we will pass them over for subjects of greater interest if of less importance4 ,every farmer knows the familiar and destructive fungus known as 8rust of wheat10 it is one of a large class of most interesting plants4 ,the 8rusts0 are interesting to the microscopist on account of their structure and to the botanist because they cannot1 like other fungi1 complete their lives upon one plant4 ,they derive their popular name from the fact that they look like patches of rust upon the plants on which they live4 ,some of the greatest living agricultural botanists have spent many years on producing races of wheat upon which rust fungus will not grow4 ,wonderful success has rewarded their efforts and conferred immense benefits upon farmers4 ,in spite of this1 however1 we need not despair that we shall be unable to find a specimen for our microscope1 though it is happily an undoubted fact that the disease is not so common now as a few years ago4 ,illustration3 ,photos by ,flatters ,garnett #a4 ,,cluster ,,cups ,the spring stage of ,rust of ,wheat4 ,little orange cup-shaped growths on the under side of a ,barberry leaf4 ,they germinate on ,wheat to form the summer stage of 8,rust40 #b4 ,,rust ,,of ,,wheat ,these little stalked spires are the winter stage of a serious disease of ,wheat4 ,in the spring they germinate on ,barberry4 #c4 ,,pollen ,,grains ,,on ,a ,,grass ,,flower ,the feathery stigmas of grass flowers are beautifully adapted for catching and holding pollen grains4 #d4 ,,the ,,lower ,,side ,,of ,a ,,fern ,,frond ,one of the brown outgrowths on the under side of a fern frond4 ,the stalked spore cases are seen1 protected by an umbrella shaped covering4 ,rust of wheat fungus grows part of its time on barberry leaves and part on wheat4 ,in the summer1 if we examine one of the rust-like patches on stem or leaf of wheat we shall see that it consists of a dense bunch of small1 short stalks each one of which is terminated by an oblong red-brown spore4 ,if we keep another patch of the fungus under observation1 we shall find as the season advances1 that instead of the red-brown patch it has grown darker and darker till it has become almost black4 ,the microscope will show us that the structure of the spores has altered considerably4 ,there is still the same bunch of stalks but they have lengthened somewhat and now each spore which terminates each stalk is divided into two parts by a wall across its narrow part4 ,the walls surrounding the spores also appear thicker1 as indeed they are4 ,these are the winter spores1 they fall to the ground eventually and there they remain1 unharmed by frost or snow or rain1 till the spring4 ,in the spring they germinate and give rise1 not immediately to another fungus1 as might be expected1 but to another kind of spore4 ,curiously enough these new spring-formed spores cannot grow upon wheat and unless they are carried by wind or some other agency to a barberry plant their existence is ended4 ,should they reach a barberry leaf1 however1 they will germinate1 penetrate the leaf and grow for a period4 ,eventually the fungus appears on the lower surface of the leaf in beautiful structures called cluster cups4 ,under the microscope1 one of these cluster cups forms a lovely object4 ,the leaf skin is split and below the ruptured skin may be seen a flask-shaped hollow filled with chains of minute golden-yellow spores4 ,the spores break away1 one by one and favoured by fortune1 are carried to a wheat plant where they germinate and give rise to the familiar rust4 ,any microscopist anxious for research has a life's work before him in tracing the histories of this one class of fungi1 should he feel inclined to shoulder the burden4 ,very many cluster cups are known and very many rusts and all that is required is an enthusiastic mycologist1 as the student of fungi is called1 to put the pieces of the puzzle together1 so to speak4 ,it is not so very many years ago that the connection between the cluster cups of barberry and the rust of wheat was quite unthought of4 ,we cannot afford much more space to plant diseases1 the farmer has other troubles and we must mention some of them4 ,we cannot leave the subject1 however1 without a word concerning the mildews4 ,as we have mentioned1 they are curious because they dwell outside the plants they attack4 ,rose mildew is unfortunately all too common in every garden1 it may be recognised as a white powder covering leaves and buds4 ,under the microscope1 in the summer we shall find that it consists of a number of thread-like structures1 not unlike those of the common white mould and that there are a number of erect chains of spores4 ,towards autumn1 a further examination will show us many round dark-brown structures from which project a number of minute threads4 ,these brown spheres are the winter stage of the fungus1 designed to withstand inclement weather4 ,in the spring1 the spheres burst and set free a number of minute sacs1 each one containing eight spores4 ,the spores germinate on rose leaves and start the disease anew4 ,there will be no difficulty in finding mildews2 they are all very similar to the rose mildew in general but they all differ in detail4 ,the gooseberry mildew for example1 has a large number of threads running from its winter spheres and each thread is terminated by a little group of branches4 ,the sacs which fall from the opened sphere in the spring1 only contain four spores in this case4 ,the animal enemies of the farmer1 so far as they concern the microscopist are more difficult to study4 ,many of them are internal parasites and to gain a real knowledge of their habits and life histories necessitates a good deal of rather unpleasant work for which the ordinary microscopist has neither the time nor the inclination4 ,in order to give our readers some idea of this work1 let us take one of the commonest of all agricultural parasites and trace its life history whilst giving hints for its examination under the microscope4 ,the common liver fluke is a worm which1 in the adult stage1 frequents the liver of some domestic animal1 usually the sheep4 ,a friendly butcher will probably be able to supply us with a specimen and1 when we receive it1 we shall probably dub it a very unwormlike creature4 ,the worms form a large class in the animal kingdom and they do not all resemble the earthworm by any manner of means4 ,the liver fluke is a flat1 almost leaf-like creature1 it is not ringed like the earthworm and1 under the microscope1 we can plainly see all its internal organs4 ,the fluke lays its eggs1 each one enclosed in a little capsule1 in the liver of the sheep4 ,they are carried to the intestines and finally set free along with the animal's excrement4 ,if then the eggs are blown1 or carried by some means to water they will continue their development1 on dry soil they cannot long survive4 ,each egg gives rise to a little organism which swims freely in the water2 it is shaded like a blunt-ended cone when extended and is roughly oval when contracted4 ,its body is covered with little whip-like structures similar to those of the slipper animalcul1 and it is due to the lashing of these little whips that the creature moves through the water4 ,if we found one of these young flukes in some pond water we might be forgiven for thinking it to be some near relative of the slipper animalcule4 ,when our subject finds a living water snail it enters its breathing organs1 becomes affixed to their walls and loses its covering of little whips4 ,it becomes transformed into a shapeless mass which later develops into an elongated structure1 quite unlike the free swimming creature which took shelter within the snail4 ,next1 a migration is made to the liver of the snail where birth is given to1 from fifteen to twenty1 curious little heart-shaped organisms each with a tail about twice as long as its body4 ,these little creatures escape from the snail and swim freely in the water for a time4 ,eventually they make their way to herbage growing by the waterside1 affix themselves thereto and become surrounded with a hard coat capable of resisting the effects of hot sun or drying winds4 ,should this herbage be eaten by cattle1 the apparently lifeless young fluke bestirs itself1 loses its tail and wends its way to the liver of its host1 then the story begins again4 ,having examined the adult liver fluke under the microscope1 we shall probably wish to find both the free swimming young forms1 and if we search carefully in ponds to which sheep have access we are likely to be rewarded4 ,it is obvious that the life of a parasite such as the liver fluke is1 of necessity1 precarious4 ,it is only chance or luck1 or whatever one's favourite term may be1 that brings the egg to water1 the young fluke to a snail1 and the last free swimming form to herbage that will be eaten by a suitable animal4 ,as usual in such cases1 nature makes provision for emergencies by providing a large number of young1 in order to insure that some at least may be able to complete their development4 ,owing to a series of changes1 which we have omitted to describe for the sake of simplicity1 each liver fluke egg may give rise to no less than three hundred and twenty of the final free swimming forms4 ,as we have remarked1 the study of parasites is difficult but it is interesting4 ,very few of these creatures can complete their lives without living at the expense of two different animals4 ,the liver fluke needs the water snail and some herb-feeding animal2 there is another parasite which spends part of its life in the pig and another part in the grub of the cockchafer2 a third parasite dwells for a time within the thrush1 and for the rest of its time within the garden snail1 and so on4 ,apart from the interest of the subject in itself1 it brings us face to face with the fact that many quite unrelated forms of animal life are essential to the well being of a number of parasites4 ,to the farmer the subject is all important4 ,insects of various kinds are all important in agriculture2 most of them are harmful1 some few are useful4 ,they have1 however1 been dealt with in another chapter1 so we will dismiss them here4 ,the ticks are closely related1 and anyone with access to a farm should be able to obtain some specimens4 ,whatever species we are able to obtain should be examined under the microscope4 ,their feet are always interesting1 being furnished with powerful claws beautifully adapted to grasping the hairy coats of their hosts4 ,their mouth parts are quite unlike those of insects1 and are always furnished with a number of backwardly directed teeth1 which are useful for tearing flesh sufficiently to draw blood on which they feed4 ,,chapter ,,xiv ,,the ,,microscope ,,and ,,insect ,,life ,some of our readers will probably remark that entomology1 or the natural history of insects1 is really a branch of zoology and should be treated as such4 ,we cannot pretend that they are wrong1 but it is such a specialized branch that it merits separate treatment4 ,not many years ago insects1 with few exceptions1 were looked upon as harmless and often beautiful dwellers upon the earth4 ,they afforded endless amusement to certain enthusiasts who collected them for their colouring or their odd forms4 ,recent developments of our scientific knowledge have shown us that the insect is1 other human beings excepted1 man's most serious rival for the mastery of the world4 ,this state of affairs has been beautifully depicted by an ,american naturalist2 his words described a by no means unlikely final scene on this earth of ours4 ,he wrote3 8,when the moon shall have faded from the sky and the sun shall shine at noonday1 a dull cherry red1 and the seas shall be frozen over1 and the ice-cap shall have crept downward to the ,equator from either pole1 and no keel shall cut the waters1 nor wheels turn in mills1 when all cities shall have long been dead and crumbled into dust and all life shall be on the very last verge of extinction on this globe1 then1 on a bit of lichen1 growing on the bald rocks beside the eternal snows of ,panama1 shall be seated a tiny insect1 preening its antenn in the glow of the worn-out sun1 representing the sole survival of animal life on this our earth--a melancholy #8bug4'0 ,there is probably no field more interesting for the microscopist than that provided by the insect world4 ,unlimited explorations may be made with the certainty of finding something new at every turn4 ,most people begin their studies of insect life with butterflies and moths2 some folk to their loss never proceed further4 ,we may well follow the usual course1 and make a butterfly our first study4 ,any butterfly or moth will do for our purpose1 any one with coloured wings1 for some have clear wings like those of the bees and wasps1 but they are not very common1 so that we shall probably find a suitable specimen at the first attempt4 ,the more highly coloured the specimen1 the more attractive it will appear under the microscope4 ,after killing the insect1 and not before1 we may proceed to study it4 ,killing may best be accomplished by means of a killing bottle1 failing this a hard nip on the body1 between thumb and finger1 will do1 but it must be no half-hearted proceeding or the insect will be injured without being killed4 ,having removed a wing and placed it on the stage of our microscope1 we must examine it by reflected light1 for it is not transparent4 ,this may be accomplished1 if we are using artificial light1 by raising the source of illumination well above the object1 so that the light strikes it at an angle of about forty-five degrees2 by daylight reflected light is easily managed4 ,if we have never previously examined a similar object we will be surprised at its appearance4 ,all the beautiful reds and blues1 yellows and greens which comprise the brilliant livery of these insects are seen1 under the microscope1 as hundreds of minute scales which overlap one another like tiles on a roof4 ,a higher magnification will show that each scale is roughly flask-shaped1 and that its narrow end fits into a little socket in the wing proper4 ,when the scales are rubbed from the wing1 nothing remains but a transparent substance traversed by veins--to the microscopist the scaleless wing is of little interest2 to the entomologist it is important1 for the moths1 at anyrate1 are arranged into families largely according to the arrangement of the veins of their wings4 ,many other wings may be examined with advantage2 gnats1 for example1 are clothed with scales of varied shape1 some hair-like1 some forked1 some resembling a sickle1 and some disc-shaped2 these forms1 by the way1 do not all occur upon the wings1 but are found upon the head and other parts of the body as well4 ,the wonderful gauzy1 iridescent wings of dragon flies are interesting2 those of various flies worth examination also those of bees on account of the clever device for uniting the front and hind wings during flight4 ,on the front edge of the hind wings the microscope will show us a row of minute hooks4 ,when the bee makes a flight1 it hooks its hind wings to a ridge on the hinder edge of the fore wings1 so that for flying purposes it has1 to all intents1 two wings instead of four4 ,having examined all the wings we can find for the time being1 we may turn our attention to mouths4 ,the mouth parts of insects are not only interesting but important2 one of the first things an economic entomologist does with a new specimen is to examine its mouth parts4 ,the mouth will tell us what manner of feeder its owner may be4 ,some insects have sucking mouths1 and they must feed perforce on liquids2 others have biting mouths1 and they are likely to do damage to crops by eating them4 ,then there are lancet-like mouths and mouths which are a compromise between biting and sucking ones4 ,the subject1 however1 is somewhat complicated1 and entails a knowledge of insect anatomy1 so we will merely deal with a few easily understood examples4 ,our butterfly has a sucking mouth2 it is known as a proboscis1 and may be found1 coiled like a watch spring1 beneath its head4 ,there is no trace of anything in this mouth capable of biting or even piercing the most delicate structure4 ,the house-fly is also possessed of a proboscis though of different design4 ,though a dangerous1 disease-carrying insect1 it can do no harm with its mouth4 ,the partiality of the house-fly for sugar is well known1 and it is interesting to learn how1 with its soft fleshy mouth1 it can satisfy its cravings4 ,let us watch one at work on a lump of sugar through our pocket lens4 ,if we look carefully we shall notice that the fly1 as he thrusts his proboscis here and there1 emits from it a little drop of liquid2 after a momentary pause the liquid is sucked up again1 it has dissolved a little of the sugar1 and the fly enjoys the sugar-laden liquid4 ,people frequently state that they have been bitten by a house-fly--a sheer impossibility4 ,what really happens is that they mistake the very similar stable fly for the house-fly4 ,if one of these insects be captured and examined1 we shall find not the soft fleshy proboscis of the house-fly1 but a cruel looking1 awl-like mouth easily able to penetrate the human skin4 ,certain tropical flies1 known as ,pangonias1 have such formidable and lengthy piercing mouths that they can penetrate thick clothing and puncture the skin below4 ,microscopists who care to follow up the study of insects' mouths will know that they are accumulating really useful knowledge4 ,those who do not desire to go so deeply into the matter may well spare a few moments for the examination of the green fly mouth1 a needle-like piercing organ which is thrust into plants for the purpose of sucking their sap4 ,the mouth of the gnat is a more difficult subject for the microscopist1 though no less interesting2 it may be compared with the same organ of the green fly1 for it is used somewhat similarly1 with the difference that it sucks blood and not plant juices4 ,it may be well to mention here that the females alone suck blood1 but it is easy to distinguish the sexes1 for the antenn or feelers of the females are thread-like whilst those of the males are feathered4 ,a few adult insects have no mouths1 for they never feed during their short lives4 ,caterpillars of all kinds and also beetles1 grasshoppers1 cockroaches and the like have biting-mouth parts1 and the student1 who is not well versed in insect anatomy1 will learn more by watching one of these insects partaking of a meal than by trying to discover the uses of the various parts with the aid of a microscope4 ,caterpillars as a rule are not shy feeders1 and a pocket lens will show their sickle-like jaws in full play4 ,the grubs of house-flies are worth examining2 they are soft and fleshy except for a pair of horny hooks which are used to tear up the food material4 ,there are1 however1 so many different mouths we cannot describe even the typical ones1 but the microscopist will soon discover those of special interest4 ,the feet of insects do not show so much variation as their mouths1 nevertheless they will afford ample material for many hours of study4 ,our butterfly1 which is now but a remnant1 will provide our first object4 ,the design of its feet will depend1 to some extent1 on the species of insect1 but they will certainly be clawed4 ,other insects with clawed feet--beetles1 bees1 and wasps--may be examined1 and we shall see that there are minor differences amongst them though their general plan is similar4 ,sometimes we find a simple pair of claws on each foot1 in other cases each claw has a little spur1 whilst spiders1 which1 by the way1 are not insects1 have comb-like claws4 ,the foot of the house-fly is not only provided with a pair of claws1 but also with a soft fleshy pad1 by means of which it is enabled to climb window panes and similar smooth surfaces4 ,if we are fortunate enough to obtain a specimen of a louse1 human or otherwise1 we must not fail to notice its strong grasping claw1 used for taking a firm hold of the hair of the creature on which it lives4 ,such objects are better examined under a high magnification1 along with a hair1 then the actual method of grasping may be observed4 ,the feelers of some insects are interesting2 those of gnats we have already mentioned1 but they may be examined in detail4 ,those of beetles are of very diverse form2 some are thread-like1 some clubbed1 some fan-shaped4 ,moths1 too1 have many curious designs to show4 ,some of these feelers1 when highly magnified1 may be seen to be pitted--hundreds of little sunken areas are scattered over their surfaces1 and it is probable that they are connected with a sense of smell4 ,in that case the feeler is a more important organ than one might surmise from its popular name4 ,the hairy clothing of insects need not delay us long4 ,most interesting of all are the feathered hairs of certain bees4 ,in our chapter on botanical work with the microscope we mentioned the feathery stigmas of grass flowers and we also stated that they took that form1 so that pollen grains blown to them would be entangled in their branches4 ,the hairs of many bees are feathered for a similar reason1 they gather pollen and the pollen adheres to these 8feathers0 much more readily and in much greater quantity1 than it would to simple1 unbranched hairs4 ,some bees collect no pollen and1 from them1 feathered hairs are wanting4 ,any microscopist who has followed us thus far1 will have a fair idea of the structure of a number of insects4 ,in every case1 where possible1 comparisons should be made between similar organs of different insects and the investigations may be made more interesting by observing the habits of the insects and trying to discover reasons for the differences in structure4 ,it is safe to surmise that there is a reason in every case4 ,there are many other interesting subjects which we have not mentioned1 the legs of insects--running legs of ground beetles1 digging legs of mole crickets1 swimming legs of water beetles and the wonderful pollen-carrying legs of bees4 ,then again1 the eggs of many insects are of surpassing beauty in shape1 they may be round1 oval1 oblong1 nearly square and almost needle shaped2 some are smooth and shining like burnished metal1 others beautifully sculptured2 some resemble miniature birds' eggs1 others are not unlike the seeds of plants4 ,many insects are too small to be cut up into their various parts1 legs1 feet1 wings1 etc41 by unskilled hands and they must be examined whole4 ,perhaps you may think that an insect will be too big an object for your microscope4 ,indeed there are some insects which measure nearly a foot in length1 but there are1 on the other hand1 beetles no longer than one hundredth part of an inch4 ,when we examined the house-fly it is not unlikely that we found some minute creatures living upon it4 ,none of these is likely to be an insect1 but as they are closely related we may mention them here4 ,beneath the wings of the house fly there are often minute1 red1 six legged young mites1 all eagerly sucking the juices of their host4 ,because they are six legged we may be led to think that they are insects1 for the entomologist knows that the true insect1 in its adult form1 never has more than six legs4 ,these mites1 however1 later in life1 drop from the fly and by developing another pair of legs appear in their true colours4 ,various other mites1 including cheesemites1 may be found clinging to the house-fly1 in fact it is by the aid of these insects that cheesemites are often carried from cheese to cheese4 ,one of the most curious parasites of the house-fly must be sought upon its legs4 ,if the search is successful1 curious1 reddish-brown creatures1 armed with formidable pincers1 and strangely reminiscent of miniature lobsters1 will be found clinging thereto4 ,they are called chelifers and their home is the manure heap1 so that their presence shows us only too well where our friend the fly has recently disported himself4 ,his next visit was probably to our food4 ,illustration3 #a4 ,,the ,,head ,,of ,a ,,beetle ,a remarkable beetle1 with enormously developed fore-legs4 ,the object of these long legs is not known4 #b4 ,,the ,,head ,,of ,,hercules ,,beetle ,this beetle1 whose head resembles a lobster's claw1 is said to carry his wife from place to place4 #c4 ,a ,,cicada ,one of the noted singing insects4 ,kept as a pet in some countries1 voted a nuisance in others1 the cicada is the medium of much romance4 #d4 ,,the ,,head ,,of ,,mantis ,this illustration clearly shows the cruel rat-trap-like front legs of the rapacious mantis4 ,if we can find a swiftly running stream within easy reach a little time may be spent in searching the submerged rocks and plants for the miniature stages of the buffalo gnat4 ,this insect1 which is known to scientists as ,simulium1 has a most interesting life history4 ,its popular name is derived from its hump-backed appearance and its supposed resemblance to a buffalo4 ,the female lays her eggs on a rock or reed1 just covered by running water1 she never lays them in still water4 ,the greenish-brown1 club-shaped grubs which come from the eggs are curious and they will repay examination under a low magnification4 ,at the more blunt end of the creature there is a large sucker2 it uses this as a foot to support itself in an upright position4 ,if we examine our specimen under water we shall see that its horny head is decorated with a pair of fans1 each one composed of about fifty threads4 ,these fans open and close with a rhythmic movement and1 in doing so1 attract small floating water plants to the mouth4 ,just below the head there is a single leg with a sucker foot4 ,when the grub walks1 it does so by a looping movement1 holding fast to its support with fore and hind suckers alternately4 ,the next stage in the life of the young buffalo gnat is even more curious4 ,on the surface of some submerged leaf we shall probably be able to find a number of the slipper-shaped pockets made of closely woven silk1 in which the insect spends the final portion of its life before turning into the perfect fly4 ,within some of the pockets we shall find the creature itself and it must be studied4 ,its head is still ornamented with a pair of fans1 but in this case they are gills by means of which the insect breathes and not food scoops1 for it has reached a stage when food is not taken4 ,on its tail end there is a hook1 by means of which it anchors itself to its slipper-shaped pocket4 ,probably we shall find bubbles of air collecting round some of the insects1 within their pockets2 as the time approaches nearer and nearer for the change to the perfect insect to take place the bubbles grow larger and larger4 ,eventually the fly emerges within a bubble1 shakes it free from the pocket and floats to the surface of the water without wetting its wings4 ,the pond will supply insects quite as interesting as the running stream4 ,here we may find the eggs of ,caddis flies1 enclosed in jelly-like envelopes1 rope-like1 horse-shoe shaped or simple masses4 ,the caterpillar cases of these insects should be slightly magnified and examined1 for they are marvellously constructed of shells or sand1 pieces of stick1 leaves or other vegetation4 ,we may come across the young stages of the common gnat4 ,its eggs are very small and when the mother gnat lays them on the surface of ponds she glues them together so that they form what is known as an 8egg raft40 ,the 8raft0 we shall notice1 if we examine it carefully1 is composed of a large number of eggs2 each egg is elongated1 pointed at one end and blunt at the other4 ,every egg is arranged with its blunt end downwards for1 from that end1 the larv gnats make their way into the water4 ,a larva1 it may be explained1 is the stage in insect development which follows the egg2 the next stage is known as the pupa4 ,when the eggs are first laid they are white but1 before they hatch1 they become darker and darker1 till they are almost black4 ,the larv which hatch from the eggs we must examine under our microscope and also in the water--they may easily be kept in a small jar of pond water4 ,if we study their habits carefully1 we shall observe that they float almost at right angles to the surface of the water and that1 while doing so1 the tip of a little peg-like outgrowth on the tail end of their bodies is thrust out of the water4 ,the little peg is the breathing organ of the gnat larva and the flaps which open and close at its tip are worth examination4 ,in a few days1 the denizens of our pond water will change their appearance and become comma shaped4 ,on their heads we shall see a pair of curious horns1 which project out of the water as the creatures1 which have now become pup1 float at the surface4 ,the horns are breathing organs4 ,as we examine these pup1 day by day1 we shall see the various parts of the complete gnat as they develop within the body of the comma4 ,finally1 under the microscope1 we can trace all the parts of the gnat4 ,darker and darker the little creatures become1 as development proceeds2 at the same time they become less active and less comma shaped4 ,at length the time comes when they straighten their tails somewhat violently1 their skin splits along the back and out comes the perfect gnat4 ,we can use him for further microscopic work1 so we will not let him go4 ,if he be a male1 his beautiful feathered feelers or1 if a female1 her thread-like feelers will make good objects for us1 the scales from head and body1 the wings and feet are all worth the time we may spend in examining them4 ,the mouth parts1 too1 are interesting but rather complicated4 ,many insects are capable of emitting more or less musical sounds4 ,in some countries these so-called singing insects are kept as pets1 in other countries the same insects are voted a nuisance2 it is all a matter of taste4 ,of all musical insects1 the most noted is the ,cicada and its sound organs are easily seen2 they occur only in the male1 for the female never sings4 ,the ,cicada belongs to the same great order of insects as the green fly1 which we have already mentioned4 ,there is one ,british species1 and our readers who visit the ,new ,forest may come upon it4 ,on the under side of one of these insects the beak1 very similar to the beak of the green fly1 may be plainly seen4 ,on either side of the insect1 just below the bases of the wings there are two nearly round discs4 ,these discs cover the sound organs1 which are two ear shaped membranes4 ,by means of muscles the insect can cause the membranes to vibrate and thus produce the sound which once heard1 can never be forgotten4 ,more easily found insects1 in this country1 at any rate1 are the cricket and the grasshopper4 ,the cricket we all know is a persistent songster4 ,let us examine him closely4 ,we shall find1 that the house cricket has two pairs of wings2 the fore wings are leathery1 the hind wings membranous4 ,if we watch a male in the act of chirping1 the male crickets like the male ,cicadas are the songsters1 we shall observe that he moves his wings slightly4 ,if now we examine a dead male1 we shall find1 on the under surface of the forewing1 a rough patch4 ,let us examine this patch under the microscope1 it reminds us of nothing so much as a file3 it is a file in fact1 and sound is produced by rubbing this rough file against a ridge1 which we can easily see1 on the upper surface of the hind wing4 ,it would be a useless accomplishment for the cricket to be able to sing1 if there were no ears to hear its song4 ,nature has arranged that his song shall not go unheard and if we examine a female cricket1 that is to say a cricket which has no sound-producing apparatus1 we shall find an oval depression1 covered by a membrane1 on each of her front legs2 these are her ears and they enable her to hear her mate calling to her4 ,we have often heard the song of the grasshopper as we have walked through the fields and he too will occupy our time for a few moments4 ,when he sings1 he kicks his legs rather violently and this gives us a clue to the situation of his vocal organs4 ,the inside of each of his hind thighs is ridged and the edge of each ridge is1 as we can see if we magnify it1 rough like a file4 ,this file-like ridge is rubbed against a smooth ridge on the edge of the fore wing and the result is the familiar note of the grasshopper4 ,this insect also has ears1 but they are not easy to find unless they are pointed out to us4 ,if we examine a grasshopper we shall see that its body is divided into three parts3 a head1 a solid portion from which the wings and legs arise1 the thorax and a portion 7the abdomen7 made up of a number of rings or segments4 ,on the sides of the first of these rings1 counting from the forward end1 we shall find small depressions covered with membrane1 these are the ears4 ,it is curious that although many of the grasshoppers cannot give out a note1 so far as human ears can detect1 they nearly all have ears2 maybe there is a grasshopper song which only grasshoppers can hear4 ,very many other insects have sound organs1 but they are nearly all constructed on the same plan4 ,it may seem surprising that sounds can be produced by these simple means4 ,sound is really caused by waves in the air and these insect vocal organs set up rapid sound waves1 by their vibration4 ,the microscopist should never be at a loss for objects derived from the insect world3 it is impossible to walk without treading upon some six legged wayfarer4 ,the wing cases of beetles are often of rare beauty1 some on account of their sculpturing1 some because of a mantle of scales4 ,in our greenhouse and garden we can find mealy bugs1 curious little powdered insects which do an enormous amount of damage4 ,the fringe wings1 or ,thrips1 are common and destructive2 examine their curious feet and their beautifully fringed wings1 the sight will repay you4 ,and lastly1 if you number an insect enthusiast amongst your friends1 enlist his aid in gathering objects for your microscope4 ,,chapter ,,xv ,,the ,,microscope ,,by ,,the ,,seaside--,,animal ,,life ,it is always surprising that the majority of microscopists never dream of examining any of the hundreds of beautiful objects which can be found by the seaside1 in the course of an afternoon's ramble4 ,that every pond will contain ample material for study1 the microscopist knows instinctively2 insect life and plant life also he studies1 but the microscope is generally left at home when a visit is paid to the seaside4 ,a rocky coast is better than a sandy one1 for rock pools yield many objects1 and the warmer southern waters of our coasts are better than the colder northern seas1 but the microscopist who finds himself on a northern sandy coast need not despair1 if he search diligently he will find material enough to occupy him for many a day4 ,nearly every rock pool will provide one or more ,sea ,anemones2 it is hardly necessary to describe these 8flowers of the sea0 as they have been called1 they are such familiar objects and the brilliant colouring of some of them makes them highly attractive4 ,in many respects ,sea ,anemones resemble the ,hydra1 one of the pond dwellers1 they are rather more highly developed1 however4 ,any ,sea ,anemone will serve our purpose because we are about to examine the little darts with which its tentacles1 and even its body1 are armed4 ,if we find several different kinds of ,anemone1 we must take the most transparent we can find and also a small specimen2 we can examine the larger1 more opaque ones later4 ,having transferred our specimen to a small jar1 containing but a small quantity of sea water1 we wait till it has recovered from its transfer and spread its tentacles1 then it must be killed by one of the methods suggested in our concluding chapter 7see p4 #cjf74 ,one of the tentacles must then be snipped off with scissors--some people cut off the tentacle without killing the ,anemone and the animal does not appear to suffer a great amount of inconvenience1 in fact a new tentacle soon grows to take the place of the old one4 ,we do not recommend promiscuous vivisection4 ,the tentacle is placed on a clean slide1 a cover slip placed over it and pressure is applied4 ,an enormous number of little thread-like darts are pressed from all parts of the tentacle4 ,in some cases1 little oval capsules are squeezed out and1 in the capsules1 the darts may be plainly seen1 coiled up4 ,on applying pressure to a capsule1 the contained dart will shoot forth1 much as does a glove finger turned inside out1 when we blow violently into the glove4 ,these little darts are of the greatest interest to the microscopist2 they vary in shape according to the kind of ,anemone1 as we shall find if we try this experiment with various ,anemones4 ,some of them are straight with stiff bristles at their bases2 some have backwardly directed barbs at their tips2 others are apparently jointed1 forming a zigzag1 with a short length of the dart going from left to right1 the next short length from right to left1 and so on to the tip4 ,it is marvellous how the darts can be accommodated within the capsule1 for the average length of the latter is but #a_/cjj inch whereas its dart may measure #a_/h inch4 ,these little threads contain a poison capable of paralyzing any moderate-sized fishes which they touch4 ,have you ever seen a 8comb bearer0 or as it is often called1 a 8marble bleb80 ,probably you have though you may not know its name4 ,sometimes it occurs in rock pools1 though more often it is found in one's shrimping net and occasionally it is washed up by the tide1 but it does not live long out of water4 ,the 8marble bleb10 as its name denotes1 is an almost globular mass of soft1 transparent jelly4 ,it is practically colourless1 with the exception of eight bright coloured bands which run from end to end of the animal4 ,to the naked eye1 this little denizen of the sea is of rare beauty3 as an object for low-power microscopy it is entrancing4 ,when magnified1 the bright bands are seen to be composed of rows of flattened outgrowths4 ,if our specimen is small enough to be examined in water1 its real beauty can only be seen in this manner1 we shall observe that the flattened outgrowths act like paddles1 sometimes they work all together1 sometimes independently of one another and this fact explains the marvellous evolutions of the 8marble bleb0 in water4 ,now it shoots forward in a straight line with some rapidity1 now it rolls over and over and swims onward while doing so4 ,in the sun1 it displays glorious iridescent colouring4 ,at the hinder end of the 8bleb0 we notice a pair of hollows3 from these1 as we watch it swim1 we shall see it suddenly shoot out a pair of long feathery tendrils and they may be withdrawn into the hollows as suddenly4 ,we must make a point of examining the 8marble bleb10 it is one of the gems of our coasts4 ,superficially the common1 sponge-like 8,dead man's toes0 or1 to give it its more pleasant title1 8,mermaid's fingers10 is a very drab affair4 ,it is a dirty-brown lobed1 spongy mass with a leathery skin2 when removed from the water it loses all semblance of shape4 ,in sea water1 however1 if we examine it carefully1 we shall see that it is studded with beautiful little flower-like creatures1 each one resembling a miniature ,sea ,anemone4 ,examined1 in water1 under a low power of our microscope we can see the water current flowing through the channels with which it is perforated1 after the manner of a sponge4 ,if1 now1 we take a dead specimen and cut it up1 placing a small portion on a slide and shredding it with a pair of needles1 we shall find1 when we magnify the result of our work1 that there are a number of minute mineral spikes1 called spicules1 and very beautiful objects they make for the microscope4 ,there are many sea-side creatures1 which we may find1 closely related to 8,mermaid's fingers10 they may all be treated in the same way for they will all yield spicules which will repay us for our trouble4 ,all these spongy organisms are not provided with spicules as ornaments1 though one might be forgiven for thinking so1 seeing how decorative many of them are4 ,their presence is necessary to strengthen the spongy material4 ,the specimen we have just examined is not one animal but a colony of very minute animals4 ,these colonies are very common1 not only in salt but also in fresh water4 ,they serve a useful purpose1 for the creatures composing them are so minute that they would fare badly did they dwell alone4 ,dwelling together as they do and each one contributing its share to the building of the home they appear to thrive to a wonderful degree4 ,the coral islands are built1 as to their foundations at anyrate1 by millions of very minute animals1 living together in colonies4 ,we mentioned the sponges a moment ago and many of them may be found around our coasts2 not the household sponges we know so well1 but much smaller1 though equally interesting1 colonies4 ,like the better known sponges1 those which we find on our shores are perforated with a number of holes through which the water is driven by means of little whip-like structures which line the cavities4 ,professor ,grant has graphically described his impressions at witnessing this water current for the first time4 8,i put a small branch of the ,spongia ,coalita10 he writes1 8with some sea water in a watch glass1 under the microscope1 and1 on reflecting the light of a candle up through the fluid1 ,i soon perceived that there was some internal motion in the opaque particles floating through the water4 ,on moving the watch glass1 so as to bring one of the apertures on the side of the sponge fully into view1 ,i beheld1 for the first time1 the splendid spectacle of this living fountain vomiting forth from a circular cavity an impetuous torrent of liquid matter1 and hurling along1 in rapid succession1 opaque masses1 which it strewed everywhere around4 ,the beauty and novelty of such a scene in the ,animal ,kingdom long arrested my attention2 but after twenty-five minutes of constant observation1 ,i was obliged to withdraw my eye from fatigue1 without having seen the torrent for one instant change its direction1 or diminish1 in the slightest degree1 the rapidity of its course4 ,i continued to watch the same orifice1 at short intervals1 for five hours1 sometimes observing it for a quarter of an hour at a time1 but still the stream rolled on with a constant and even velocity4 ,about the end of this time1 however1 ,i observed the current to become perceptibly languid 444 and in one hour more the current had entirely ceased40 ,frequently the sponge we examine may be found to be studded with many yellowish spots2 closer examination will show that these spots are composed of very small jelly covered eggs4 ,later these eggs find their way into the cavities of the sponge and are forced therefrom in the currents of water4 ,each of the young sponges thus expelled is furnished with a covering of little whips1 by means of which it swims about till it can find a suitable spot on which to anchor and complete its growth4 ,the ,sea ,anemone1 which has already provided us with objects for our microscope1 has many near relatives which we must make a point of examining1 while we have the opportunity4 ,many of these creatures1 or rather their colonies1 for they do not live singly1 are to the naked eye1 strangely like seaweeds4 ,a number of them are moss-like and may be found on wooden breakwaters and similar situations when the tide is low2 they should be collected and examined and1 to see them at their best they should be examined under water4 ,it is hardly necessary to describe any one of these colonies in detail1 for they are so numerous that the one we described might not come into the hands of our readers for a long time4 ,in general characters they are all somewhat similar so we will confine ourselves to generalities4 ,for the most part1 the stems and branches of these colonies are of the thickness of thread4 ,as we watch them under the microscope we shall see that they are studded with little cups and1 presently1 from each little cup there appears a little tuft of tentacles which is waved about in the water4 ,each member of the colony is similar to its neighbour and each one1 again1 is very like the fresh water ,hydra with which we are familiar4 ,of all the common objects of the sea shore one of the commonest everywhere is the sea-mat4 ,nine people out of ten or1 we might safely say that everyone who had not learned its true nature1 would guess it to be a seaweed4 ,as we find it washed up on the beach it is almost the colour of sand1 somewhat rough to the touch1 whilst its whole surface is pitted with minute holes4 ,the sea-mat1 when dry as we usually find it1 is a remnant of a colony of sea dwellers very similar to those we have just described4 ,from each little hole1 in a living specimen1 which we can find without much difficulty1 there appear the familiar tentacles2 each hole is the home of a minute hydra-like animal4 ,hooke1 whom we mentioned in our chapter on the ,history of the ,microscope1 though a careful observer1 was quite misled by the sea-mat2 he thought it was a seaweed1 for he wrote3 8,i have not1 among all plants and vegetables ,i have yet observed1 seen any one comparable to this seaweed4 ,it is a plant which grows upon the rocks under water and increases and spreads itself into a great tuft1 which is not only handsomely branched into several leaves1 but the whole surface is covered over with a most curious knot of carved work1 which consists of a texture much resembling a honeycomb1 for the whole surface on both sides is covered over with a multitude of very small holes1 being no larger than so many holes made with a pin1 and ranged in the neatest and most delicate order imaginable1 they being placed in the manner of a quincunx1 or very much like the rows of eyes of a fly1 the rows or orders being very regular which way soever they are observed4 ,these little holes1 which to the eye look round1 when magnified1 appear very regularly shaped holes1 representing almost the shape of a round-toed shoe1 the hinder part of each being1 as it were1 turned in1 or covered by the toe of the next below it4 ,these holes seemed walled about with very thin and transparent substance1 looking of a pale straw colour1 from the edge of which1 against the middle of each hole1 were sprouted out four small1 transparent1 straw-coloured thorns1 which seemed to protect and cover those cavities40 ,as a well-known author has remarked3 8,this is really a wonderfully faithful description of the common sea-mat1 and one cannot help picturing the surprise and delight of old author ,hooke1 could he have seen a portion of a living colony under a modern microscope40 ,one of our finds may be the 8,bird's head40 ,it is a branched form1 quite unlike the sea-mat but it is of even greater interest4 ,under the microscope1 we shall see the many waving tentacles1 but another feature is sure to attract our attention1 a feature which is responsible for the popular name of the colony4 ,on the outside of each cavity containing a member of the colony there is a structure which resembles nothing so much as a hawk-like bird's head atop of a long neck4 ,while the tentacles wave in the water1 the bird's head snaps vigorously1 moved here and moved there4 ,the birds' heads1 which might be mistaken for parasites stealing food from the waving tentacles1 really perform the useful function of keeping them clean and warding off creatures which might do them harm4 ,illustration3 ,by the courtesy of ,messrs4 ,f4 ,davidson ,co4 #a4 ,a ,,section ,,of ,,human ,,skin ,the corkscrew-like pores1 leading from the sweat glands to the surface1 are plainly seen in the section4 #b4 ,,the ,,face ,,of ,a ,,fly ,a wonderful photograph1 at #ae inches1 taken by the micro-telescope4 ,notice the very large size of the eyes relative to the rest of the head4 ,now let us pass to quite different though equally common sea shore animals1 the star fish4 ,there are very many kinds but the common star fish will serve our purpose well4 ,we may make a beginning by examining his back under a low magnification and observing that it is protected by a number of hard plates which form a very efficient armour4 ,at the point where two of the rays 7the finger like structures7 arise we shall notice a small flat plate1 this too is worth a moment's inspection1 for it is the water pore through which the star fish takes in water4 ,the under surface of the star fish shows us of course its mouth in the centre of its body1 the soft fleshy suckers which cover the rays1 with the exception of a narrow line down the centre of each one4 ,at the tip of each ray there is an eye2 it may easily be distinguished by its bright red colour and microscopic examination will show us that it is quite unlike any of the other eyes we have examined4 ,over each eye there is a little tentacle2 these little tentacles may be called the noses of the star fish1 for1 by means of them it is able to smell4 ,they are as unlike our idea of a nose as are the little pits on the feeler of the cockchafer which we examined1 yet these noses and ours all perform the same duties4 ,our time will be well spent if we devote some of it to a search for others less common star fish4 ,some of them are really beautiful and whatever specimens we come across can be compared with the common variety which is everywhere4 ,closely related to the star fish are the sea-urchins4 ,the relationship may not be apparent at first sight but a careful study of an urchin and a star will reveal many points of similarity4 ,our object in these pages1 however1 is to find material for our microscope and not to unfold the relationships of various members of the ,animal ,kingdom4 ,when we have learned to cut sections1 we may try our hand at the spine of a sea-urchin1 it is an object well worthy of study4 ,the hard shell of the urchin may be examined under a low magnification1 we shall see then that his armour is far more highly developed than that of the star fish4 ,another near relative of the two animals we have just described is the sea slug or sea cucumber4 ,though an article of commerce of some importance in the far ,east1 the sea slug is not so common on our coasts as its relations4 ,we must make a point of finding a specimen1 however1 for it provides us with one of the most remarkable objects for our microscope that could possibly be imagined4 ,one species1 which goes by the name of ,synapta ,inhrens1 is the one most worthy of examination4 ,we must describe the creature first of all so that we may know what to look for4 ,it is aptly named sea cucumber for it is not unlike that fruit--yes6 fruit is correct1 though the cucumber is more often called a vegetable4 ,the animal's skin is tough and leathery and at the head end there is a fringe of feathery tentacles4 ,the sea cucumber must be looked for amongst sea weeds or1 maybe1 he lies buried in the sand1 with only his fringe of tentacles on view4 ,a friendly fisherman will probably aid us in our search4 ,having found our creature we must examine his leathery skin under the microscope4 ,to the touch it is evident that it is studded with some flinty matter1 but the microscope alone can show us the amazing beauty of this armour4 ,under a low magnification1 we can see1 dotted over the leathery skin1 some nearly circular plates to each of which is attached a little anchor4 ,now1 from a dead animal of course1 we must scrape away some of these objects and examine them with a higher magnification4 ,even the hardened microscopist will be delighted when he sees the armour of the sea cucumber for the first time4 ,each anchor is hinged to a little plate1 each little plate1 nearly circular in outline1 is perforated with seven holes1 six round the circumference and one in the centre and every perforation has a toothed margin4 ,so perfect are these minute plates and anchors1 that the most intricate man-made machinery could not have turned them out more perfectly to pattern4 ,they are precisely similar to one another in size and shape2 as objects for the microscope1 even the sea with all its store of wonders1 can offer us nothing more marvellous4 ,we may number the sea mouse amongst our treasures of the sea-side4 ,though called a mouse1 on account of its curious movements and partly perhaps because of its appearance1 it is really a worm4 ,it does not appear to have the slightest resemblance to the common earth worm1 nor to the liver fluke which is described on another page1 nevertheless1 it is related to both these creatures4 ,the raiment of the sea mouse is gorgeous in the extreme2 on its back is soft brownish hair1 its sides are clothed with yellow and green hair1 displaying a wonderful iridescence and amongst the hair on the sides there are many stiff brown bristles4 ,of the covering of the sea mouse it has been said3 8,it is as if all the hues of the rainbow were collected there1 making this remarkable animal a living jewel1 and truly worthy of the name of ,aphrodite1 the ,queen of ,beauty40 ,the bristles of this creature we must examine microscopically1 they vary in structure according to the kind of sea mouse1 for there are several kinds1 but in some of them they are formidably barbed1 in all of them they act as a protection4 ,many other worms1 a number of them un-wormlike in appearance will claim our attention but we cannot devote more space to them here4 ,there is the common shell-binder1 a curious worm1 which builds for itself a still more curious shelter of broken shells4 ,another worm1 ,serpula by name1 also lives in tube-like structures of its own manufacture and is remarkable in that a row of nearly two thousand seven-toothed hooks run along its back and all these thirteen thousand odd teeth are there merely for the purpose of holding ,serpula in its tubular home4 ,much interesting work may be done at the seaside in studying the young stages of various familiar creatures4 ,this work1 however1 necessitates the keeping of the adults in an aquarium2 for the young ones1 in most cases1 are so unlike their parents that1 if found swimming about on their own account1 they would never be recognised4 ,young barnacles1 for instance1 have six legs1 a tubular mouth and a single eye4 ,at a later stage they might be mistaken for young shell fish2 they possess a shell1 not unlike that of the mussel1 containing1 however1 not a soft1 fleshy mollusc but a six legged creature which swims through the water in jerks1 after the manner of a water flea4 ,strangely enough1 it is now provided with two stalked eyes like those of a crab1 whilst of mouth parts it has none1 or they are so imperfectly developed as to be useless for feeding4 ,soon this active youngster settles down for the rest of its life and becomes a sedate and sedentary barnacle1 with one imperfectly developed eye and a mouth capable of feeding to good purpose4 ,young crabs are equally curious and also totally unlike their parents1 but these curious creatures are hardly accessible to those who only pay a flying visit to the sea-side4 ,as we have remarked1 an aquarium is a necessity and to keep marine animals inland is a feat beyond the powers of the ordinary mortal4 ,the ,sea ,lemon or ,doris is a curious little creature1 worthy of examination4 ,its habit is to feed upon sponges and strange diet it is1 for we remember that all sponges are fortified with hard flinty structures1 called spicules4 ,this habit of the ,sea ,lemon is of use to the microscopist1 for the stomach of the creature is always laden with the indigestible spicules and a very interesting collection of these beautiful structures may be gathered together in this manner4 ,the egg masses of ,doris may be looked for on rocks during the summer4 ,enormous numbers of eggs are laid in a jelly-like mass4 ,some of this jelly may be collected and examined under the microscope and1 should we have collected our material at a favourable moment1 we may watch the eggs hatch and observe the young ,sea ,lemons in their delicate transparent shells swimming round and round the chamber within which they are imprisoned during the very early stages of their lives4 ,very frequently in the summer1 when the seas are warm any agitation of the water causes a beautiful phosphorescence to appear4 ,phosphorescence1 by the way1 may be described as light without heat and it is not uncommon in nature4 ,glow worms and fireflies are phosphorescent2 fish1 also1 in the dead state1 often emit a certain amount of light as do bones whilst1 of course1 phosphorous itself is the best example of a naturally phosphorescent body4 ,phosphorescent sea water1 however1 owes its peculiarity to myriads of minute animals and they will afford us an interesting half hour with the microscope4 ,let us collect a little of this water in a glass jar and take it into a darkened room that we may the better see the phosphorescence4 ,when the water in the jar is undisturbed1 we can see nothing unusual2 if we stir it or strike it a faint greenish light is given off1 but it does not last for long4 ,now1 on taking the jar into the daylight1 as soon as our eyes are accustomed to the light1 we shall just be able to see that there are some very small living creatures on the surface of the water4 ,we must examine one1 under a fairly high magnification2 it may be transferred1 from the jar to a drop of water on our slide1 by means of a paint brush4 ,the little animal which is responsible for the phosphorescence of sea water is strangely reminiscent of an apple with its stalk4 ,it is1 of course1 very minute being only #a_/fj inch in diameter and its tail1 which we have compared to the stalk of the apple1 is equal to the diameter in length4 ,the whole creature is quite transparent4 ,as we watch it swim in our drop of water1 we shall notice that it propels itself by the lashing of its tail4 ,there are countless animals of the sea we have not so much as mentioned1 but the marine gardens contain plants so interesting and so totally unlike those which live upon land that we must devote a few pages to them also4 ,,chapter ,,xvi ,,the ,,microscope ,,by ,,the ,,seaside--,,plant ,,life ,the plant life of the sea side may be divided into two natural groups 7i7 of plants living on the shore near the sea and 7ii7 of plants living in the sea1 for part of each day at least4 ,the former group contains many plants of exactly the same kind as occur far inland1 together with a few typically sea-side plants such as ,thrift or ,sea ,pink4 ,they are1 however1 one and all land plants4 ,in this chapter we shall confine ourselves to the real sea plants1 the seaweeds4 ,before we study any of these interesting plants under the microscope1 it will be useful to learn a little about seaweeds in general1 because they are so totally unlike land plants in every respect4 ,they belong to the great plant division known as the ,alg1 to which also belong the ,diatoms1 ,desmids1 ,volvox1 ,spirogyra and many of the other plants we mentioned in our chapter on ,pond ,life4 ,so we see that1 although all seaweeds are ,alg1 not all ,alg are seaweeds4 ,they are higher in the scale of development than ,fungi1 to which ,bacteria1 ,yeast1 ,mould1 etc41 belong1 though they are not so highly developed as ,ferns and not nearly so advanced as flowering plants4 ,a very short acquaintance with ,alg will show us that they are either green1 brown or red4 ,the green ,alg are nearly all fresh water forms1 though a few are to be found in the sea2 on the other hand brown and red ,alg are common in the sea and rare in fresh water4 ,as we study our seaweeds on the shore1 if we are really observant1 we shall notice that they live in zones or belts according to their colour4 ,there are exceptions to this rule but1 in general1 the green seaweeds dwell in situations where they are only covered by the sea at high tide2 the red seaweeds are to be found mostly where they are always below water and1 between the two1 the brown seaweeds occur4 ,in some parts1 this colour scheme is very striking4 ,frequently red seaweeds may be found above high-water mark it is true1 but in such cases they nearly always occur in rock pools and they are invariably sheltered by brown seaweeds4 ,in our chapter on plant life we mentioned that many coloured plants contained the green colouring matter1 chlorophyll1 just as do the ordinary green leaves4 ,we showed too that by boiling some green leaves in methylated spirits we could extract the chlorophyll and that its solution had the peculiar property of appearing green when light passes through it and red when light is reflected from it4 ,if now we take almost any brown or red seaweed1 we cannot see a trace of chlorophyll anywhere4 ,let us leave our specimen1 however1 in fresh water for a few days when we shall find that the brown or red colouring matter as the case may be1 is dissolved by the water and a green plant remains4 ,by treating the seaweed1 deprived of its distinctive colour1 with methylated spirit as described above1 we can obtain a solution of chlorophyll4 ,the microscopist who is anxious to make a study of seaweeds1 will find little scope for his hobby on a sandy shore4 ,just as the most interesting marine animals are to be found where rocks abound1 so must we hunt in similar situations for our ,alg4 ,a few thread like ,alg are able to anchor themselves to the sand but most of them require a substantial support4 ,a bare rock is a much favoured situation and before we have learned the peculiarities of these plants we may marvel how they obtain any sustenance from so barren a resting place4 ,as a matter of fact they derive no nourishment from the rocks on which they rest4 ,the part of the sea weed which1 in our ignorance1 we may have dubbed a root1 is nothing of the kind4 ,it bears no relationship to the roots of higher plants and is a mere anchor1 designed to fasten its owner to a support4 ,none of these plants have roots1 none have true stems or leaves1 though the parts resembling stems and leaves are often so called2 none of them flower and so fruits and seeds are unknown to them4 ,their food is absorbed from the sea water over the whole of their surface4 ,we may well begin our study of the seaweeds with an examination of the external structure of as many different kinds as we can find4 ,some of them are flattened and very thin forms and of them the ,sea ,lettuce may be taken as typical4 ,this plant1 known to scientists as ,ulva ,lactuca1 occurs at high-water mark4 ,in its fully developed form it is pale green and so thin as to be almost transparent2 its structure may be studied under the microscope without difficulty4 ,then there is the very common1 green1 ,compressed ,enteromorpha which grows in great profusion on the rocks of the shore1 rendering them exceedingly slippery4 ,the closely related ,intestinal ,enteromorpha as it floats in the water resembles a green1 membranous tube and those of us who have ever done any zoological dissection will appreciate how well named this plant is4 ,the structure of both the ,enteromorphas can easily be seen4 ,many of the brown and red ,alg will provide us with a good deal of occupation in making out their structure4 ,some of them1 the brown ,ectocarpus ,siliculosus for example1 may be found1 growing in moss like tufts1 which are usually attached to one of the larger ,alg living between the tide marks4 ,it is one of the simplest of the brown sea weeds1 consisting of branched threads1 but one cell in thickness4 ,the ,wracks1 of which the ,common ,bladder ,wrack or ,pop weed with its little air filled bladders is familiar to everyone1 are more complicated in structure1 in fact they appear to be possessed of stems and leaves1 but we shall return to them in a moment4 ,most of the common red ,alg are so delicate in structure that they require a fairly high magnification for their examination4 ,the thin1 membranous fronds of the beautiful crimson ,delessera ,sanguinea1 may be sought below low tide limit or may be found washed up upon the shore4 ,superficially the plant resembles a red hart's-tongue fern1 with much more delicate fronds than ever fern of that species possessed4 ,we may well compare its structure with that of the sea lettuce1 for it is equally transparent4 ,in the rock pools of many parts of the coast we may happen upon a most curious almost white sea weed1 known as ,coralline or ,corallina ,officinalis4 ,its branched1 feathery stems are hard and stony and the whole plant bears a superficial resemblance to a coral1 hence its name4 ,the plant absorbs a substance known as calcium carbonate from the sea water and deposits it in the form of a hard1 stony covering over its surface4 ,calcium carbonate does not occur in sea water everywhere1 at least not in sufficient quantity to be of use to the ,coralline1 that is the reason the sea weed is not quite so common as some of the others we have mentioned4 ,the curious armour-plating of this sea dweller1 should be studied under the microscope4 ,the chief scientific interest of the sea weeds1 however1 lies in their mode of increase1 it is so totally different from that of any of the higher plants4 ,the most simple method of increase is known as vegetative reproduction1 it does not occur in every kind of seaweed and is nothing more or less than the growth of a broken piece of plant into a new individual4 ,this form of increase is not unknown higher in the plant world2 begonia leaves may be induced to send forth roots and grow into new plants1 many garden favourites are propagated by means of cuttings and both these methods are similar to the breaking away and growth of portions of a seaweed2 the garden plants1 however1 are assisted by man1 the seaweed does its own work4 ,the simplest forms of increase occur amongst those giants of the sea1 the ,laminarias or ,tangles as they are often called4 ,these brown seaweeds often attain enormous sizes1 they all grow below the limits of low tide and appear to thrive best where the water is frequently lashed by storms4 ,to see these plants at their best we must look down upon them in their watery home4 ,there are spots on the ,north-,eastern coast of ,ireland1 where one may look from the cliffs upon a veritable forest of ,tangles4 ,there thrives the 8,devil's ,apron10 short of stem but with a flat ribbon of a frond1 which may attain a length of a dozen feet and a width of as many inches4 ,there too we can behold the ,fingered ,tangle1 with stem1 maybe1 six feet in length and a crown of large finger-like fronds1 8,sea ,laces0 or 8,dead ,men's ,ropes10 with fronds resembling slender ropes1 in length1 at times as much as forty feet1 ride gracefully on the ever changing currents4 ,safely hidden in this marine forest lurk queer fishes and crabs and shell fish4 ,about the broad fronds of the 8,devil's ,apron0 sea mice and sea cucumbers disport themselves2 the ,tangle home is a paradise for marine life4 ,yet with all their vigorous growth they increase simply by liberating spores which give rise to new plants4 ,in our chapter on ,plant ,life we described spores very briefly2 we said that from a strictly scientific point of view they were not comparable to seeds but that for our purpose they might be looked upon as seeds for the reason that1 by their germination1 new plants were formed4 ,all the spores of land plants are minute1 they are carried from the mother plant to suitable spots for germination by wind4 ,the spores of seaweeds also are small1 but they are very different to the little wind-blown1 land-dwelling spores4 ,they possess a pair of the curious little whip-like structures we have observed in so many water plants and animals4 ,by the lashing of these little whips they are able to swim about in the water till they find a suitable spot to settle down and grow into plants similar to those whence they came4 ,on account of their animal-like movements they are called zoospores4 ,the formation of zoospores may be easily observed in the brown sea weed ,ectocarpus ,siliculosus we have already mentioned4 ,this plant1 as we have already remarked1 consists of thin1 thread-like rows of single cells and from time to time it is branched4 ,at certain periods of the year1 moderately large1 pear shaped swellings occur on the threads of the sea-weed4 ,if we are either fortunate or exceptionally patient we may chance to be examining one of these swellings under the microscope at the moment when it bursts and sets free its contents4 ,should we have this good fortune we must hasten to magnify more highly the zoospores which have escaped from the pear shaped spore case4 ,here we may add the caution that we shall only witness the bursting of the spore case if we examine our specimen in sea water2 we should require more than the patience of ,job to watch for its bursting in the dry state1 for it will never come to pass4 ,a careful study of a zoospore will show that it swims in a peculiar manner4 ,one of the little whips is directed forwards1 the other trails behind4 ,after a short period of activity the zoospore comes to rest1 loses all means of propulsion1 germinates and grows into a new ,ectocarpus plant4 ,sometimes this ,alg reaches a low ebb of vitality1 it requires a new lease of life as it were1 when this state is reached another form of increase takes place4 ,the events in this case may also be witnessed under the microscope4 ,from very similar spore cases a number of zoospores are liberated and for a time they swim about freely4 ,if now we watch carefully we shall notice that one of the active little bodies comes to rest and that the others lose no time in swarming round it4 ,one of these swarming zoospores fuses with the individual which first ceased swimming about1 with the result that a much larger1 non-swimming individual is formed which1 after a short resting period1 germinates and grows into a new sea weed4 ,the remainder of the zoospores will come to rest later and germinate to form new plants just as though no fusion had taken place with two of their number4 ,here we see the beginnings of male and female increase amongst sea weeds2 the individual which first comes to rest is looked upon as the female and the one with which it fuses as the male4 ,illustration3 ,by the courtesy of ,messrs4 ,f4 ,davidson ,co4 ,,the ,,feeler ,,of ,a ,,cockchafer ,the end of the feeler consists of a number of plates1 which can be spread fanwise4 ,the pores visible on the plates are the insect's organs of smell4 ,amongst the ,wracks1 of which there are a number of kinds1 the methods of increase reach a higher stage4 ,first of all let us describe the plants1 so that we may know what to look for4 ,they all belong to the group of brown ,alg4 ,the 8,channelled ,wrack0 is1 when fully grown1 about six inches long4 ,it is much branched1 often almost yellowish in colour and grows just below high-water mark4 ,along one side of the plant there is a moderately deep groove4 ,here we may note that the ,wracks grow in zones from just below high water mark to low water mark4 ,a little nearer the sea than the haunts of the ,channelled ,wrack1 we shall find the ,flat and ,bladder ,wracks4 ,the former is but six inches or so in length1 with flat1 forked fronds1 along the centres of which runs a single rib4 ,the ,bladder ,wrack varies considerably in size4 ,it may be smaller than either of the ,wracks we have already mentioned or it may be two or three feet in length4 ,it is the one seaweed familiar to everybody4 ,nearer to low tide mark we shall encounter the ,knobbed ,wrack1 greenish brown in colour and often as much as six feet in length4 ,it is so named because from the sides of its flat1 leathery1 strap-like fronds1 there arise little stalked bladders4 ,right at1 and often beyond1 low tide mark there dwells the ,notched ,wrack2 very similar to1 though larger than1 the ,flat ,wrack1 from which it may easily be distinguished by the fact that the edges of its fronds are toothed1 after the manner of a saw4 ,it is obvious that the structure of any one of these ,wracks is much more complicated than is the case with ,ectocarpus4 ,the latter ,alga was composed of a number of cells1 similar to one another in every respect except size4 ,if we tease a stem or a frond of one of the ,wracks upon a slide and examine the result of our efforts under the microscope we shall see that the cells which compose the ,wrack are not by any means similar to one another4 ,those of us who have mastered the1 by no means difficult1 art of section cutting1 should cut sections of stem and frond and compare them with sections of leaf and stem of some higher plant4 ,the comparison will show us that1 although the seaweed does not exhibit the complicated structure of a flowering plant1 it has at least three kinds of different cells--an outer layer1 a central structure and an intermediate layer4 ,if we secure a specimen of the ,channelled ,wrack1 at the end of the summer1 we shall notice that the tips of certain of the fronds are swollen4 ,examination of these swellings under a low magnification will reveal a number of wart-like structures1 and at the end of each wart there is a little pore4 ,if we open up one of these little warts1 very carefully with our mounted needles1 we shall find that each little pore opens into a cavity1 within which we can find two kinds of structures1 hidden amongst a number of hair like growths4 ,we shall see a number of dark1 oval bodies1 at the base of the hairs1 these are the egg cells2 more careful search will show us a number of much branched structures also partly concealed by the hairs1 these are the male organs of the plants4 ,the purpose of the hairs1 by the way1 is to keep the little chamber moist1 when the plant is left high and dry4 ,if we watch the pores of the other warts carefully we may be fortunate enough to see the process of increase taking place1 for it occurs outside the plant and not within the chamber4 ,the egg cell divides into two and its contents pass out of the chamber by way of the pore2 each cell of the male organs gives rise to sixty-four oval little structures1 each provided with a pair of minute whip-like threads by means of which it swims from the chamber and goes in search of the egg cells4 ,many of these little navigators are lost by the way but one of them will reach and fuse with each egg cell4 ,after fusion the new-formed cell germinates at once into a new ,channelled ,wrack4 ,that this is an advance is shown by the fact that the little swimming bodies which fail to fuse with the egg cell1 do not develop into new plants as in ,ectocarpus nor does the egg cell1 which has failed to fuse with a swimming body1 germinate4 ,in the ,bladder ,wrack1 a very similar process takes place4 ,there are1 however1 certain important differences1 differences which show that the plant is still more highly developed4 ,if we examine the cavities1 in the little warts of the ,bladder ,wrack we shall find that some of them contain egg cells1 some contain male organs but none contain both4 ,we noticed that the egg cell of the ,channelled ,wrack produced two eggs1 that of the ,bladder ,wrack produces eight4 ,in other respects the two plants behave similarly4 ,the methods of increase amongst the red seaweeds are rather more complicated and as our object is to interest and not to puzzle our readers we will content ourselves with a few general remarks4 ,microscopists who are anxious to probe more deeply into the subject will soon devise ways and means for themselves4 ,the little swimming bodies which lend an added attraction to the study of the brown seaweeds are replaced1 amongst the red ,alg1 by organisms with but one whip-like structure apiece and that without the power of propelling its owner through the water4 ,as with ,ectocarpus1 increase may take place in two ways4 ,on these red plants we may find the now familiar swellings1 which we have learned to know are spore cases1 but instead of the multitudes of free swimming organisms which are set free on the bursting of the brown sea weed spore case1 we now witness the expulsion of but four inert spores1 which settle down in the water and immediately grow into new plants4 ,in the second method of increase1 where male and female organs are concerned1 we find that both these structures grow on the outside of the plant and not in cavities4 ,let us take the common1 pink1 much branched seaweed1 known by the fearsome name of ,callithamnion ,corymbosum as our example4 ,the male organs grow in little fungus like tufts about the branches of the plant and they give off enormous numbers of little organisms which have no power of swimming to the female organs4 ,either on the same or on another plant we shall find the female organs2 we need not describe them in detail but there is one point of very great interest4 ,from each of the female organs there grows a long jelly-like hair4 ,as we have remarked1 the organisms set free by the male organs cannot swim about but float aimlessly in the water4 ,obviously the majority of them simply perish1 one perchance may touch a sticky hair to which it adheres1 with which it fuses and passes down to the female cell1 resulting in the production of a new seaweed4 ,it may be remembered that in writing about the pollen grains of flowering plants1 we mentioned that those plants dependent upon wind for the distribution of their pollen1 have stigmas ingeniously contrived for catching and retaining the grains4 ,it is curious that the red seaweeds should have very similar contrivances for capturing and retaining the male cells4 ,the sea will also provide us with a rich harvest of those beautiful microscopic objects1 the ,diatoms4 ,they may be sought on seaweeds1 their yellowish brown colour often betrays their whereabouts1 on rocks and sand and in mud4 ,the salt water forms are as varied and as beautiful as their fresh water cousins4 ,to the microscopist who merely uses his microscope for the pleasure he can derive from it1 rather than for serious study1 it may appear that the plant life of the sea falls short of the animal life as far as interest is concerned4 ,he may disabuse himself at once of this idea4 ,there is no class of plants more interesting than the seaweeds and in few branches of plant life is there greater scope for new discoveries4 ,the garden of the sea is largely an unexplored territory and there is no coast-line in the world of equal extent which provides so many different sea dwelling plants as our own4 ,,chapter ,,xvii ,,the ,,micro-,,telescope ,,and ,,super ,,microscope ,those of our readers who have borne with us thus far may quite excusably have thought that the last word had been attained in the construction of the microscope4 ,it is true that different makers have made various improvements to their instruments1 from time to time in recent years1 most of them of minor importance but useful in the aggregate4 ,but a few years ago1 however1 the advent of the ,micro-,telescope and ,super-,microscope marked an epoch in the manufacture of the microscope4 ,we have shown that great strides were made in scientific investigation when the first simple lenses were manufactured1 that there was a lull in microscopic research till the appearance of the compound microscope and now1 when the latest instruments are in the hands of scientific workers1 further possibilities are opened up4 ,in all microscopes--the best as well as the cheaper instruments--there is one failing which very early forces itself upon the user4 ,they have very little 8depth of focus40 ,let us explain exactly what the phrase means4 ,once or twice in our pages1 we have recommended that the fine adjustment should be rotated to and fro while certain objects are being examined4 ,when potato starch grains1 for instance1 are magnified sufficiently highly to show their characteristic markings1 the whole of the grain cannot be seen clearly at one time1 because at that magnification the 8depth of focus0 is slight4 ,the higher the magnification the less is the 8depth of focus02 when this quality is absent altogether only one plane of an object can be viewed clearly without re-adjusting the focus4 ,with low magnifications1 we may1 to a limited extent1 have more than one plane of an object in focus4 ,the same question of 8depth of focus0 occurs in photography and perhaps an example showing how it affects the camera user may make the matter clearer4 ,suppose we wish to photograph a landscape having1 let us say1 a tree in the foreground1 a cottage in the mid-distance and a hill in the distance4 ,if our lens is one of large aperture1 that is to say admits a considerable amount of light and is also what is known as a long focus lens we shall find1 when we view the scene on the ground glass1 that when the tree is sharply focussed1 the cottage and hill are not clear4 ,when we rack in the camera to get the cottage sharply focussed1 the tree and hill will be un-sharp4 ,similarly when we focus on the hill the tree and cottage remain out of focus4 ,the reason is that the lens in our case possesses little 8depth of focus40 ,the experienced landscape photographer1 did he wish all three objects to appear equally sharp could easily attain his object4 ,he would perform the simple operation known as stopping down his lens1 that is to say he would gradually close its diaphragm1 while viewing the scene on the ground glass4 ,at a certain point everything would be sharp1 from foreground to distance4 ,at the smaller aperture of the lens1 caused by closing the diaphragm1 the depth of focus would be considerably increased1 at the same time much less light would be admitted to the camera4 ,looking upon our object1 under the microscope1 as comparable to a landscape1 seen on the ground glass focussing screen of a camera1 it is obvious that1 unless our object has no thickness1 and this is impossible1 we cannot highly magnify its upper and lower surfaces at one and the same time4 ,there are no adjustable diaphragms in the objective so our only course is to examine the two surfaces in turn or to resort to a lower magnification4 ,illustration3 ,by the courtesy of ,messrs4 ,f4 ,davidson ,co4 ,,the ,,micro-,,telescope #a4 ,view taken with ordinary camera4 ,the arrow shows the building illustrated in the plate below2 it is #c_/d mile away4 #b4 ,the building indicated by the arrow in the plate above1 taken from the same standpoint through the micro-telescope4 ,apart from any other consideration1 the super microscope marks a big advance from the fact that it possesses great 8depth of focus40 ,it is possible1 for example1 with this remarkable instrument to examine a moss as it grows1 with a high magnification and see not a portion of a leaf or a fragment of the stalk1 as with the ordinary microscope1 but the whole upstanding plant1 in stereoscopic relief4 ,it shows us objects exactly as we should see them were we endowed with super eyes1 enormously enlarged1 in relief and erect4 ,objects viewed through this instrument are not inverted1 as with the ordinary microscope4 ,illustration ,a is the microscope proper and is1 in all respects1 similar to the instrument with which we are familiar1 except that its mirror and condenser have been removed4 ,in the fitting provided for the condenser a second microscope is arranged4 ,illustration ,this consists of a tube ,d1 an objective ,f1 an ocular ,c and an inner sliding tube ,e1 the whole fits into the metal case ,b1 ,g is a stage on which the object is placed and below ,g1 if necessary1 a condenser may be fitted4 ,the instrument owes its remarkable magnifying powers to the fact that the additional microscope ,b1 forms a magnified image of the object on the stage ,g1 at the opening in the stage of the microscope ,a4 ,this magnified image is still further enlarged by the original microscope4 ,in other words1 the power of one microscope is employed on that of another4 ,the apparatus as we have described it gives enormous magnifications and it is possible1 by using a suitable combination of objectives1 to obtain a magnification of ten thousand diameters4 ,expressed in non-technical language1 a circle whose actual diameter is equal to the thickness of the paper upon which these words are printed1 could be so magnified by the super-microscope that it would appear to be as thick as ten thousand similar pieces of paper but1 with this enormous magnification1 it is obvious that1 even with such a marvellous instrument1 the whole of the circle from edge to edge could not be seen at one time4 ,with an ordinary microscope a magnification of one thousand three hundred diameters is considered highly satisfactory4 ,so that there is a great probability of being able to see some of the minute objects which are known to exist1 but which have1 up to the present1 eluded those who would view them1 on account of their minuteness4 ,there is a possibility also of discovering a new underworld of which no man has yet dreamed4 ,the man who uses his microscope solely because of the pleasure he derives from it1 rather than he who uses it because it is essential to his business or profession1 will be more attracted by the micro-telescope4 ,by this we do not infer that the instrument is not useful1 as a fact it is of the greatest importance in certain cases1 especially for ,nature-study work1 for the observation of minerals and to the chemist4 ,like its sister instrument1 the micro-telescope consists of an ordinary microscope to which is attached a specially designed object glass in a tube1 which take the place of the condenser4 ,the makers1 indeed1 provide two of these object glasses--one for viewing objects from one to two feet away1 the other for viewing objects from a distance of three feet to the planets1 if need be4 ,once when the instrument was being tested some crumbs were placed on the floor at a distance of four yards and strongly illuminated1 and the microscope with a #a-;inch objective focussed on the crumbs4 ,with this objective in an ordinary microscope the magnification would be about thirty diameters4 ,presently some mice came out1 and made themselves at home with the crumbs4 ,the mice could be examined at this distance1 without their being aware of it1 so well that individual hairs were easily visible and about half a mouse was in the field of view4 ,in point of size each mouse appeared about the same as a beaver within a foot or two4 ,messrs ,f4 ,davidson ,co41 #bi ,great ,portland ,street1 ,london1 are well known for the high state of perfection to which they have brought the micro-telescope and other instruments connected with microscopy4 ,the novelty of the micro-telescope will appeal strongly to the ,nature lover4 ,at a distance of a few feet a spider can be magnified to the size of a large cat1 and it can be watched spinning its web with spinnerettes the size of teacups4 ,ants at a distance of six feet are seen to be fearsome individuals1 six inches in length1 and their tiny burdens are so magnified that they appear like yule logs or goodly-proportioned boulders1 according to their nature4 ,at a distance of ten feet a wasp may be seen scraping tiny shavings of wood from oak palings by means of its jaws--shavings which it converts into paper for building its nest4 ,very small insects may be observed as they come into the world from their chrysalis stage4 ,the never-tiring jaws of the caterpillar may be seen at work devouring some favourite leaf--the whole action of biting and swallowing the vegetable matter can be plainly seen4 ,such interesting events as the tending of green flies by ants1 the leaf-cutting habits of the leaf-cutter bee1 and a hundred and one other events are all revealed by the micro-telescope and at such a distance that the living objects are not disturbed in their activities1 being quite unaware that they are under observation4 ,to the botanist the instrument is no less useful4 ,in various manufactures1 such as ore smelting1 and in the manufacture of glass1 china and pottery1 in enamelling and in certain engineering shops1 where it is necessary to examine material at a high temperature1 the micro-telescope is a great boon1 and1 at least1 is the means of avoiding considerable physical discomfort4 ,it is used also by architects and surveyors for examining the condition of the factory chimneys1 bridges1 derricks and the like4 ,to the engineer the instrument is invaluable2 we have explained elsewhere how necessary it is that various metals and mixtures of metals should be examined for fractures4 ,under the high magnification with the ordinary microscope1 even with an instrument specially designed for the work1 only a very small area can be studied at once4 ,with the micro-telescope a relatively large area may be examined under a high magnifying power4 ,there are three features of this ingenious apparatus which cannot fail to commend themselves equally to the casual worker and the serious microscopist4 ,all objects are seen erect1 just as the eye sees them4 ,this is brought about because1 as in the case of the super-microscope1 we really observe a magnified1 inverted image of our object1 formed at the spot where the object would be placed were we using an ordinary microscope4 ,this image is inverted once more in the microscope and so it appears to us erect4 ,all objects appear in relief and in their proper planes2 this is seen in a striking manner by viewing an ordinary photograph through the apparatus1 when the various parts stand out as in nature4 ,there is also enormous depth of focus4 ,with the attachment for viewing objects at a short distance1 the whole of a tubular shaped flower such as a daffodil may be in focus at once1 from the tip of the petals to the bottom of the tube4 ,with the attachment designed for long distance work1 objects from twenty yards to sixty miles may be clearly viewed at one and the same time4 ,a few of the unsolved problems confronting the microscopist are reviewed in our concluding chapter4 ,whether they will ever be solved we dare not venture to say2 but1 if they are to be1 surely to this latest arrival in the microscopic world and to its companion1 the super-microscope1 the honours will go4 ,,chapter ,,xviii ,,chemistry ,,and ,,the ,,microscope ,to thoroughly comprehend the various uses to which the chemist may put his microscope1 it is necessary to have a knowledge of chemistry4 ,the science is so wide in its scope that no single chapter could do justice to it4 ,there are analytical chemists1 scientists whose aim is to find out the composition of various substances2 biological chemists who deal with the many problems of life in which chemistry plays a part1 but we need not attempt to detail all the branches of this highly specialised science4 ,chemical analysis is founded upon the fact that when certain chemicals are mixed together they will1 or they may1 unite to form quite a different chemical4 ,this newly formed chemical is probably a different colour to the substances which were used in its making1 or again the original chemicals may be soluble in water and the new chemical insoluble1 in which case it will form a cloudiness known as a precipitate4 ,an example may help to make our description clearer4 ,suppose we take some common table salt and dissolve it in a little water in a glass1 then add to this a little solution of nitrate of silver1 which is sold under the name of lunar caustic1 we shall find that a white cloudiness is formed when the liquids mix1 although originally they were both clear4 ,the reason of this cloudiness is that the two substances1 dissolved in water have united with one another to form a third substance which will not dissolve1 therefore it settles down as a fine powder4 ,long experience has taught analytical chemists exactly what chemicals to add to test for all the common substances1 by the formation of these precipitates2 so that1 if any powder were given to one of these scientists he could tell its composition by applying certain tests4 ,in this chemical analysis considerable quantities are required and it is often necessary to test very small samples1 so small that the ordinary methods are out of the question4 ,this is where the microscope scores1 because with this wonderful instrument1 only drops are required and tests of corresponding delicacy may be made2 in fact1 by modern microscopic methods it is possible to detect the presence of as little as ten thousandth part of a grain of arsenic1 or quicksilver or of the deadly poisons1 ,strychnine or ,prussic ,acid4 ,in testing for poisons the microscope is invaluable4 ,frequently only the most minute traces of the poison occur in the system and the modern microscopist who makes a study of poisons and their detection can solve mysteries which would have baffled all the scientists in the world in days gone by4 ,our chemical studies with the microscope may well begin with various common crystals2 they are usually easy to prepare2 the process of crystallization is always interesting to watch1 and as objects for the microscope it would be difficult to find anything more beautiful than these home-made gems4 ,all crystals should be examined by reflected as well as by transmitted light4 ,when we are working with the former lighting1 a piece of black paper beneath the slide will help to show up the objects to better advantage4 ,the easiest method of obtaining crystals of any substance which is soluble in water is to make a saturated solution in this liquid1 to put a small drop upon a slide1 then to tilt the microscope slightly so that there is a thin film of solution at the upper side of the drop4 ,the microscope must not be tilted so much that the liquid runs from the slide on to the stage4 ,where the film of liquid is thin crystals will be found first4 ,a word of explanation is necessary concerning the term saturated solution1 especially as we may have occasion to use it many times4 ,when we add a solid to a liquid in which it is soluble1 we shall find that the liquid will take up a certain amount of the solid and no more2 when1 on the addition of more solid it fails to dissolve1 we have reached the saturation point4 ,a saturated solution then is a liquid in which the maximum amount of solid is dissolved4 ,we have already described the most simple way in which crystals may be formed1 and we may easily make objects for our microscope in this manner of all the substances we can find which are soluble in water4 ,with some we shall find that crystals do not form easily1 in which event we may modify our tactics and warm one drop of saturated solution on the slide till nearly all the moisture is driven off1 then there should be no difficulty in watching the crystals in process of formation4 ,common salt1 sugar1 alum1 borax1 washing soda1 iron sulphate1 called also green vitriol and copper sulphate1 or blue vitriol1 are common and easily obtained substances1 all soluble in water4 ,as we carry our experiments a little further we shall find that crystals formed from cold solutions as suggested in our first method differ from those formed from hot solutions4 ,again1 if we use some other substance than water as our solvent the crystals which separate out will differ once more4 ,many very interesting experiments may be tried on these lines4 ,many beautiful crystals may be obtained by dissolving various substances in gelatine or gum4 ,the method is simple4 ,gently warm a little gelatine1 to which is added an equal volume of water1 in a chemist's test-tube4 ,when the gelatine has all dissolved make a saturated solution of the substance1 from which crystals are derived4 ,green or blue vitriol are good subjects for the experiment4 ,add a little of the saturated solution to the gelatine and stir with a glass rod1 taking care to avoid the formation of air bubbles4 ,a little of the mixture may now be placed in a thin film on a slide covered with a cover slip and left to cool4 ,examination when cool under the microscope will show lovely fern-like crystals1 whose beauty rivals that of ice crystals familiar to us on our window panes during hard weather in the winter4 ,barium chloride also produces very beautiful fern-like crystals when treated in this manner4 ,chlorate of potash1 familiar to most of us as a remedy for sore throat1 forms crystals totally dissimilar to those substances we have named4 ,having made as many crystals as we wish from water and also from gelatine solutions1 we may turn our attention to gum arabic4 ,the method of obtaining crystals from this substance is exactly similar to that described for gelatine except1 of course1 that we substitute gum for gelatine4 ,this work is of the greatest interest1 for not only does it yield wonderfully beautiful objects for our microscope1 but it is a hobby full of surprises4 ,when we are about to examine a new crystal for the first time we can never so much as hazard what shape it will assume4 ,sugar1 it may be mentioned1 does not crystallize at once from a saturated solution in water1 and the best method of obtaining the crystals is to warm the slide1 on which we have placed a drop of solution1 and then when dry to set aside for a day2 at the end of that time1 especially if the air be moist1 the crystals will have formed4 ,we shall find it interesting to try experiments in mixing two different substances1 then we shall probably obtain crystals totally unlike those of either of the ingredients4 ,as an example of this method1 let us make a saturated solution of a mixture of blue vitriol and magnesium sulphate in water4 ,place a drop of the solution on a slide1 heat over a flame1 not only till dry1 but till the substance left on the slide begins to melt4 ,we must use every care not to crack the slide1 and this may best be accomplished by keeping it moving while over the flame4 ,now if we watch our object through our microscope we can witness the formation of wonderful feathery crystals1 as the slide cools4 ,some strikingly beautiful results may be obtained in another manner2 the method is used by analysts in their so-called fusion tests4 ,we take a small grain of some substance1 say1 lead nitrate1 place it in the centre of our slide1 cover with a cover slip1 and warm over a flame till it melts4 ,then1 taking a similar-sized grain of another substance1 such as saltpetre1 we place it against the edge of the cover slip on the side opposite to the lead nitrate4 ,further warming will cause the saltpetre to melt1 and run below the slide and mix with the lead nitrate4 ,if we watch the meeting of the two chemicals a wonderful sight will reward us4 ,the lead compound forms a 8beautiful crystalline skeleton10 whilst the saltpetre forms six-sided stars at the opposite side of the cover slip4 ,the experiment may be repeated1 using lunar caustic and saltpetre1 also the iodides of silver and potassium2 in fact we may try any chemical substances we have at hand1 though we shall find that some do not melt very easily1 and potassium chlorate is somewhat dangerous1 for it forms explosive compounds with certain substances4 ,the number of interesting and beautiful objects which may be obtained by so-called solution tests is practically unlimited1 and the enthusiastic microscopist will certainly try all the tests we describe as well as many others of his own invention4 ,should the chemist wish to detect the presence of aluminium in very small quantities1 he relies on his microscope and proceeds in the following manner4 ,he takes a drop of the solution1 suspected of containing alum1 and adds to it a drop of sulphuric acid4 ,this mixture he puts on his slide1 which he heats over a flame till dry4 ,now he adds a drop of water1 and then a very small amount of calcium chloride is brought to the edge of the water4 ,beneath his microscope he can now watch the formation of beautiful colourless1 eight-sided crystals which denote the presence of aluminium4 ,a word of warning is necessary concerning this and the following experiments2 they may not always succeed1 for success largely depends upon having the solutions at the right strength1 and experience alone can teach us what is correct4 ,interesting and easily formed crystals may be obtained from barium sulphate1 and the experiment may also be made to show the phenomenon which we have already mentioned1 that the form of the crystals depends on the nature of their solution4 ,a little barium sulphate should be dissolved in strong sulphuric acid4 ,here1 by the way1 another warning3 every care should be taken in the use of all acids2 they should never be allowed to come into contact with face1 hands or clothes1 nor should they touch any part of the microscope4 ,some acids give off fumes1 and these should not be allowed to reach the eyes or nose1 and the microscope must be protected from them4 ,to continue our experiment3 ,while hot a drop of the solution of barium sulphate in sulphuric acid should be transferred by means of a glass rod to a slide and allowed to cool4 ,examination with the microscope will show that the barium sulphate has formed small rectangular scales4 ,with the remainder of the sulphuric acid we now make a saturated solution of barium sulphate1 and find1 on repeating the method described above1 that the chemical has formed curious x-shaped crystals4 ,similar experiments may be tried with calcium sulphate with the certainty of interesting results4 ,many crystals of calcium1 in the form of calcium oxalate1 may be found in plants1 and they are well worth looking for4 ,they may best be seen in sections of the plants1 but1 if we have not mastered the art of cutting sections1 we may find them by teasing the plant cells apart with our mounted needles4 ,in the stems of rhubarb there is the substance in bundles of long needle-shaped crystals1 to which the name of raphides has been given4 ,in the seed of the garden poppy1 just below the skin1 there is a layer known as the crystal layer1 where crystals of calcium oxalate occur as tiny balls called crystal sand4 ,in the leaf stalks of begonias very beautiful and occasionally very large crystals of this substance may be found1 whilst in shapes they are strikingly varied4 ,in orris root there are enormous crystals of calcium oxalate2 in fact it is common in many plants4 ,if we have a photographic friend who will supply us with quite a small quantity of gold chloride1 we shall be in a position to try three most interesting experiments and to obtain some curious crystals4 ,we require a very weak solution of gold chloride in water1 not more than #c4e per cent4 for our first experiment4 ,mix one drop of this solution with the same quantity of hydrochloric acid on a slide and heat over a flame till dry4 ,the microscope will now show us probably the most curious crystals we have ever examined2 some are long1 some short1 and some a zigzag in form2 mixed with these there will be a few flat plate-like crystals with rectangular projections4 ,all these curious crystals are yellow4 ,if instead of hydrochloric acid we use a solution of common salt in water and repeat the experiment as before1 we shall obtain pale yellow prisms and some crystals of common salt4 ,gold is costly1 so it is perhaps lucky that one of the tests for this rare metal is one of the most delicate known to chemists2 it is possible1 in fact1 to detect very minute quantities of gold4 ,for this experiment we may take an exceedingly weak solution of gold chloride and place a drop on our slide2 we also require a solution of the chloride of tin1 known as stannous chloride1 in an evil smelling liquid called chlorine water4 ,if now we watch our drop of gold solution under the microscope1 and while watching mix with it a drop of stannous chloride solution1 a strikingly beautiful purple colouration is produced--this purple has been named the purple of ,cassius4 ,illustration3 ,by the courtesy of ,messrs4 ,f4 ,davidson ,co4 #a4 ,,the ,,eye ,,of ,a ,,cockchafer ,this section shows the eyelashes1 the convex lenses1 and1 in the lower portion of the plate1 the nerve fibres leading from the brain to the eye4 #b4 ,,hooks ,,on ,,bee',s ,,wing ,the row of hooks on the margin of the bee's wing are clearly shown4 ,by their aid the fore and hind wings are fastened together when the insect flies4 ,if we desire further experiments in the testing of common substances1 and incidentally in the production of beautiful crystals1 we might do worse than try the effect of adding a solution of platinum chloride to any solution containing a compound of potassium4 ,charmingly beautiful crystals will result4 ,the experiments we have described as well as hundreds of others are used by analysts every day in the testing of various substances4 ,we have started in every case by knowing what our solutions contain2 the duty of the analyst is to discover what he has before him4 ,given an unlimited quantity of a substance for testing purposes it is not always easy to determine its composition4 ,with very small quantities1 perhaps less than a tea-spoon full in all1 the difficulties of the analyst are increased tenfold and without the assistance of the microscope his efforts would be unavailing1 he deals in drops and every drop is precious4 ,sad to relate this form of testing1 known to science as micro-chemical analysis1 has been practised to a far greater extent on the continent than in this country4 ,those of our readers who wish to try the experiments we have described for themselves can obtain all the necessary substances1 except the poisons1 at any chemists and the quantities required will only be the smallest that can be obtained1 in fact any reasonable-minded chemist would probably let a microscopist whom he knew have a few grains of a large number of chemical substances1 suitable for this work1 at the outlay of a few pence4 ,the chlorides of gold and platinum we fear no one will give away4 ,all the experiments we have described thus far have necessitated the use of what are called inorganic substances1 they may be described in every day language as substances derived from the inanimate world4 ,there are many equally interesting tests which may be carried out with animal and vegetable products4 ,formic acid is the substance which renders the sting of ants so painful2 it may1 however1 be prepared artificially and if a little1 dissolved in water1 is mixed with a solution of silver nitrate we shall obtain flat plate like crystals also some resembling fine fibres4 ,probably the most curious of the easily obtained crystals from vegetable products1 may be made from citric acid which occurs in lemons4 ,if a little of the acid be mixed with a solution of caustic soda and boiled with calcium chloride1 a drop of the liquid after boiling placed on a slide will give crystals readily4 ,when viewed from above they are an elongated oval shape1 described by some authorities as resembling a whetstone4 ,viewed from the side they have a striking similarity to small sheaves of wheat4 ,with the recognition of poisons under the microscope we need not trouble ourselves here4 ,it would be useless to describe any of the experiments1 for few of us could obtain such deadly substances as nicotine1 strychnine1 aconite1 morphia and the like4 ,nevertheless the recognition of these and similar substances in very minute quantities is rendered easy1 to those who have the necessary knowledge1 by means of the microscope4 ,,chapter ,,xix ,,the ,,use ,,of ,,the ,,microscope ,,in ,,manufactures ,in how many branches of commerce1 we wonder1 does the microscope play its part4 ,it is used in several departments of engineering for examining steels and many other metals not only for defects but to see how they are made up4 ,it is used in brewing for studying the various yeasts and other substances1 including the hops which go to the making of beer4 ,all manufactures which depend upon fermentation1 such as wine and vinegar making1 are largely dependent upon the work of the microscope4 ,in dairy work the microscope is invaluable4 ,in the examination of various fabrics the assistance of the microscope is always summoned4 ,paper manufacture and paper testing give work for the microscopist but it would1 we think1 be easier to give a list of the branches of commerce in which the microscope is not used than to attempt to enumerate those which make use of the instrument4 ,we cannot possibly describe all the uses to which the microscope is put1 so we will confine ourselves to one or two of the more important and1 at the same time1 to those which can1 for the most part be repeated at home4 ,the two most important commodities for mankind are food and clothing2 we cannot live without food and those of us who take but little pride in our appearance1 must have clothing of some sort4 ,we have said a little about food in another chapter and there we have also mentioned the impurities which find their way1 by accident or design1 into some of the commoner foods4 ,in this chapter we will deal first of all with clothing describing how many of the raw materials may be recognised under the microscope and showing very briefly how fraud in connection with the manufacture of wearing apparel is detected4 ,practically all clothing is made from animal or vegetable fibres1 some1 however1 is made of artificial fibres and these we shall mention4 ,the vegetable fibres used in the manufacture of wearing apparel are all either hairs or what are called bast fibres and the latter1 in non-scientific language1 may be described as the strands which run through the roots and stems of most plants4 ,the chief requirements of vegetable fibres1 destined to be woven into fabrics1 are strength1 it is obvious that a weak fibre would be useless2 length1 the longer the fibre the better and as we shall see later1 short fibres are often made up into inferior material2 pliability1 a stiff fibre would make an uncomfortable fabric2 firmness and durability4 ,animal fibres used in the manufacture are either hairs or silk4 ,the most important vegetable fibre is cotton1 it consists of the hairs from the seed coats of several species of ,gossypium1 a plant closely related to our common mallow4 ,there are very many different kinds of cotton and the qualities of the fibres of these different cottons vary tremendously4 ,each hair is one cell and more or less spindle shaped1 that is to say1 thicker towards the middle than at the base4 ,if we can obtain a little raw cotton we should certainly examine it under the microscope2 this may best be done by laying one or two fibres in a drop of water on a slide4 ,under the low power1 the first thing that will attract our attention is the fact that the fibres are twisted1 corkscrew fashion1 though not regularly nor throughout their whole length4 ,this curious twisting makes raw cotton easily recognised and it is1 at the same time1 a very valuable peculiarity of these plant hairs4 ,the greater the number of twists and the greater their regularity1 the more valuable the cotton becomes for weaving purposes4 ,under a higher magnification1 we recognise other characteristics of the cotton fibre4 ,each fibre is somewhat flattened1 its edges are thick and1 running up the centre1 there is a fairly broad lumen1 as it is called4 ,covering the whole there is a skin which by the way is often wanting in the fibres of cotton fabric owing to the chemicals with which the raw cotton has been treated and also to the methods of manufacture4 ,a very striking experiment may be tried by soaking a few cotton fibres in cuprammonia1 a substance prepared by the action of ammonia solution on copper filings4 ,constrictions occur at fairly regular intervals along the fibre so that1 after treatment with cuprammonia1 the cotton fibres resemble strings of little beads4 ,the manufacture of mercerised cotton has become very important of late years4 ,the process is named after its inventor1 ,mercer1 and consists in removing the skin from the fibres1 causing them to untwist and1 by doing so1 to impart to them a lustre of silk4 ,we may make a little mercerised cotton for examination under the microscope by soaking some raw fibres for a short time in a solution of caustic soda or caustic potash and then washing them in water to which a little acid has been added4 ,this will cause the fibres to untwist and also destroy the skin1 but we shall probably notice that the fibres have shrunk4 ,in the process of manufacture precautions are taken to prevent this shrinking for then the lustre is much better4 ,we shall also observe that in our mercerised fibres the lumen has become very narrow and it is often broken1 here and there are swellings on the outside of each fibre1 corresponding to the positions of the twists4 ,mercerised cotton1 in addition to its lustre1 is stronger and absorbs dyes more easily than ordinary cotton4 ,flax consists of the bast fibres of the flax plant4 ,examination of the raw product under the microscope will reveal both long and short fibres4 ,the former are the more valuable and are used in the manufacture of linen1 the latter are made into tow4 ,the long fibres1 which are derived from the upper parts of the flax plant have thickened edges and a very small lumen4 ,the short fibres1 used for making tow1 come from the lower part of the stem and the roots of the plant4 ,each fibre has a broad lumen and is very similar to hemp fibre4 ,examination of all these fibres1 by the way1 is best made in water as described under cotton4 ,hemp is another bast fibre and as we have remarked it resembles the short fibres of flax2 there is a broad lumen with an indistinct margin4 ,if we have an opportunity of comparing these fibres under the microscope we shall see that many of those of hemp have forked ends4 ,this is very characteristic of the plant and is never found in flax1 therefore it affords a ready means of distinguishing hemp from flax4 ,fine linen should never contain hemp1 so that if our object be to test the quality of a sample of linen by microscopic examination1 we must keep a sharp look out for the forked fibres of hemp4 ,in coarse linen these fibres occur for hemp is used in its manufacture4 ,jute1 another important fibre is readily distinguished under the microscope1 for its margins have perfectly smooth walls and its lumen is wide in some places1 narrow in others and interrupted altogether in places4 ,illustration3 ,photos by ,flatters ,garnett ,a ,,spider',s ,,foot ,the toothed claws are well adapted to enable their owner to obtain a firm grasp of the fine threads of its web4 ,,the ,,foot ,,of ,a ,,fly ,the two claws enable the fly to walk up rough surfaces1 whilst the suckers between the claws give it a firm hold on smooth surfaces4 ,there are an extraordinary number of vegetable fibres which are woven into articles of commerce1 of one kind and another4 ,then again1 many fibres are so short or so brittle that they cannot be woven but are used for other purposes such as filling cushions1 cheap bedding1 etc4 ,there are also a certain number of vegetable fibres which are valuable because they are stiff and bristle-like as well as durable1 and they are used for brushes1 door mats and for similar purposes4 ,to the microscopist who is interested in this work there is a wide field open4 ,for the examination of paper1 which may be described as a 8felt of finely divided fibres10 the microscope is invaluable4 ,the essentials of a good paper are that it be durable1 that it retain its colour and not become brittle4 ,the least observant of us cannot fail to have noticed that there are an extraordinary number of different kinds of paper1 not only the many kinds which the paper manufacturers could show us1 but the obviously varied papers which we meet with every day4 ,added to the papers1 there are cardboards which are really a kind of paper4 ,it is clear1 therefore1 that the man who can tell us exactly how any and every paper is made and what it is made of has laid up a goodly store of knowledge4 ,in carrying out tests of paper we rely partly on chemical and partly on microscopic tests4 ,a number of substances contribute to the manufacture of paper2 linen and cotton rags1 hemp and various fibres are the most commonly used1 not forgetting wood pulp which we shall mention in a moment4 ,the finest and whitest paper is made from linen rags and that from unused linen and hemp is the strongest4 ,without attempting to describe in detail or even in outline the different processes which the various vegetable fibres must undergo before they appear in the guise of paper1 we may say the treatment is very drastic4 ,strong chemicals and machinery designed to reduce the fibre to the finest possible particles render the examination of paper1 for the purpose of discovering its composition1 far from easy4 ,such fibres as survive the rough treatment are mere fragments yet they are often large enough for the lynx eyed microscope to read their story4 ,formerly the constituents of most papers could be separated into three classes according to their behaviour with iodine solution1 but this test has been superseded by more complicated methods which do not concern us here4 ,the examination of various papers may prove interesting for example in linen rag paper1 we ought to find some flax fibres1 they will be sadly battered and torn but are usually recognisable under the microscope4 ,hemp paper is tough and is used for bank notes1 in it some of the short tow fibres will probably occur and they will give a clue to its composition4 ,cotton rag paper is easily recognised for the fibres are very characteristic1 a remark which also applies to jute paper1 the so-called manila used for envelopes1 wrappers1 etc4 ,mechanical wood pulp which enters so largely into the manufacture of paper is easily recognised by those who have given a fair amount of attention to the microscopical examination of plant life4 ,wood pulp is always used in conjunction with some binding material such as cotton or flax fibres4 ,many different kinds of wood are converted into pulp and of course it requires a considerable amount of experience to say exactly what kind of wood has been used in a certain paper4 ,some of the woods are poplars of various kinds1 others spruces and firs4 ,it is easy to distinguish the conifers as spruces and firs are called1 for the reason that the trees bear cones4 ,the little fragments of wood1 scattered throughout the paper1 have minute circular perforations upon them1 resembling miniature quoits1 if they belong to the conifers2 none of the other woods possess these 8pits0 as they are called4 ,very many other plant remains may be found in paper1 for instance hop fibres are used sometimes and their presence is usually shown by remnants of the climbing hooks which1 during life1 studded the climbing stem of the hop4 ,some of the important animal hairs1 used in the manufacture of clothing1 may now claim our attention4 ,wool and silk are of course the most important4 ,the best wool is all obtained from the domestic sheep so let us examine one or two of the easily obtained hairs from this animal4 ,as with the vegetable fibres we may examine them in a drop of water but1 in this case1 we shall find that we cannot make the water go near the wool for the reason that the latter is covered with a film of grease1 called wool fat4 ,our first care1 therefore1 it to get rid of the wool fat and this may be done by shaking the specimen with a little ether or chloroform4 ,having cleaned the wool fibres we may proceed to examine them under a high magnification and1 to see their structure fully1 we must move the fine adjustment to and fro1 for it is not possible to obtain a true idea of its structure without doing so4 ,we shall see that the hair consists of two layers1 an outer skin and an inner core4 ,the latter consists of a number of cells1 whilst the former is composed of scales1 of which the lower edges are arranged beneath the upper edges of the previous scales1 like tiles on a roof4 ,the free edges of the scales project outwards a little so that the wool1 when not so highly magnified1 appears to have a toothed margin4 ,further examination will show us that no single scale completely envelops the strand of wool1 usually two scales make the complete circuit4 ,it is a curious and easily tested phenomenon that in say an inch of wool from the same kind of sheep there are always the same number or very nearly the same number of scales4 ,by counting the scales1 experts can tell from what animal the wool is derived4 ,if we examine many samples of wool we shall not be long before we encounter certain specimens showing one or more constrictions4 ,now we all know that the reason why some people do not grow very much is because they are delicate1 ill health affects the whole system4 ,the constrictions in the sheep's wool occur because the animal has suffered from some illness1 or from great hunger or thirst1 which has resulted in its wool not growing properly for a period corresponding to the duration of the illness or other calamity4 ,the examination of various animal hairs will help to while away many an hour and many of these objects are of the greatest interest4 ,if we have the opportunity it will be interesting to compare the wool from different kinds of sheep1 that from the ,lincoln sheep1 for example differs from that of shortwooled kinds4 ,we may also compare goat's wool with sheep's1 then there are differences between the hair of cows and calves4 ,comparisons always make microscopic work more interesting4 ,the microscopic examination of cloth1 used for making our coats1 is quite interesting work and withal important4 ,a good deal of the cloth which is made up into suits is known as shoddy1 that is to say that material that has been worn before2 old rags of all sorts and many other extraordinary things go to the making of this cloth4 ,there are special factories to which rags are sent to be made up into shoddy4 ,one might think therefore that this substance would be easily recognised under the microscope but it is not quite so easy as we shall see4 ,absolutely pure wool from the sheep giving the best quality wool is only used in the very finest and most expensive fabrics4 ,in a great deal of really good cloth we may recognise other hairs besides those of the sheep and sometimes vegetable fibres find their way into good cloth by accident4 ,a piece of suspected cloth should be cut off and separated as far as possible into its different fibres4 ,in shoddy we shall find few long fibres and they will all be much torn for the reason that the rags from which the material is made are cut up in the manufacture4 ,if we find cotton fibres1 we may be certain that our specimen is shoddy1 also if we can find fibres of many different colours1 though the final dyeing may have disguised the fact that the fibres have originally figured in fabrics of various colours4 ,silk is one of the most important of all fibres capable of being woven into fabric4 ,it is hardly necessary to remark that it is formed by the fully fed silkworm just before it turns into a chrysalis4 ,a very large number of caterpillars spin silk but the majority of this silk is useless for commercial purposes4 ,the silkworm gives off a double thread of silk from glands in its mouth and1 at the same time1 it gives off a sticky substance called silk glue which sticks the two fibres together1 so that1 to the eye at least they appear as one fibre4 ,most of us have kept silkworms1 those who have not may find it worth while to expend a few pence in some of these insects for the sake of examining the raw silk4 ,a cocoon1 as the work of the caterpillar is called1 consists of three layers1 an outer layer of floss1 a middle layer and a so-called layer 7the inner layer7 of parchment4 ,only the middle layer is used in commerce1 the floss is too fine and weak and the parchment is so impregnated with silk glue as to be useless4 ,if we examine some raw silk1 taken from the middle layer of a cocoon1 we can easily see the two parallel fibres of silk and the outer wrinkled covering of silk glue4 ,now1 magnifying our object more highly1 we shall see that each fibre is a solid rod1 with a smooth lustrous surface and without any sign of lumen or cell structure2 the rods too are continuous and this alone distinguishes silk from all other fibres animal or vegetable4 ,two tests are worth trying for they are characteristic of silk4 ,on the addition of a little strong sulphuric acid we observe that the silk rapidly dissolves1 on the other hand1 if a few fibres are boiled in hydrochloric acid1 the silk dissolves but the envelope of silk glue remains unchanged and appears beneath the microscope as a cracked and wrinkled tube4 ,the caterpillar of another moth spins coarser greyish coloured fibres1 which are spun into the well known ,tussore silk4 ,as with the common silkworm these caterpillars spin two fibres and glue them together with silk glue4 ,in this case1 however1 under a high magnification we shall notice that the fibres are marked with a number of very fine lines running lengthways1 whilst every now and then there are fairly deep indentations4 ,the former markings are natural to the fibres1 the latter are caused by one fibre being pressed against the other4 ,in countries where the production of silk is of great importance1 the microscope is not only pressed into service for examining the product of these useful little insects1 but also in keeping watch for a very deadly disease which attacks the caterpillars4 ,it is called 8pebrine0 and the great scientist ,pasteur1 whose name is world famous for his work on bacteriology1 discovered that it was caused by a tiny fungus4 ,artificial silk is an important article of commerce4 ,it is made in several different ways and of various substances4 ,some artificial silk is made of collodion1 some again is made of cellulose the substance of which the cell walls of young plants is composed2 gelatine is also used in making this commodity4 ,as a rule it is easy to distinguish artificial from real silk1 for usually the imitation consists of flat fibres or at least fibres quite different to the smooth rods of real silk4 ,the iodine test is often sufficient indication1 for with this chemical true silk is coloured brown4 ,space or lack of it does not allow us to describe how the microscope may be and is applied to other manufactures1 even the miller uses the instrument1 for it will tell him if his flour is of pure wheat1 and in this manner4 ,he puts a little flour in a drop of water on a slide and covers with a cover slip2 then1 for a moment or two1 he rubs the cover glass to and fro over the water and flour and examines his specimen under the microscope4 ,if his flour be of wheat1 he will see fairly stout spindle shaped strings1 if it be of rye no strings appear1 whilst maize flour gives very small strings4 ,these are called gluten strings and wheat is very rich in gluten4 ,,chapter ,,xx ,,the ,,microscope ,,and ,,camera ,,allied ,photography is such a popular hobby in these days1 that the enthusiast who possesses both camera and microscope1 is certain1 sooner or later1 to wish to take permanent records of some of the beautiful objects revealed to him by the latter instrument4 ,the production of high-power photo-micrographs1 as the pictures of highly magnified objects are called1 can only be carried out by those who are skilled in the use of both camera and microscope and are possessed of considerable patience4 ,there is nothing to prevent any amateur photographer who possesses a bellows camera--box cameras cannot be used for this work--from producing excellent low-power photo-micrographs1 that is to say pictures of objects less highly magnified4 ,it may be disappointing to learn that a microscope is not necessary for this work4 ,the requirements are1 a camera which will open out to a considerable extent and a short focus lens4 ,before we show how the pictures may be taken1 we must be quite clear what is meant by a short focus lens4 ,there are various ways of measuring the focus of a lens2 in the case of a single lens the operation is fairly simple1 but single lenses are made of one glass and most camera lenses are built up of several pieces of glass1 then it is much more difficult to measure the focus quite accurately4 ,for ordinary purposes and for our purpose1 it is only necessary to know the focus in round figures and to do so we open up the camera and focus some distant object on the ground glass1 then the distance in inches from the back of the lens to the ground glass will give us very nearly the correct focus1 or as it is often called focal length1 of our lens4 ,suppose we focus on a church steeple a mile away and then find that a space of five inches separates the back of our lens from the ground glass1 the lens is of five inches focal length4 ,with a lens of such a focal length we shall require a camera with very long bellows to obtain much magnification of our object but1 if our camera is one with only short bellows1 we can still overcome our difficulties4 ,if the extra expense is no object we can obtain one of the excellent ,aldis lenses of only two inches focal length1 especially designed for this work2 if we are ingenious we can construct a device which will answer our purpose admirably and cost but a few pence4 ,with the simple apparatus we are about to describe photo-micrographs up to ten diameters magnification can be obtained in most cameras4 ,the term1 ten diameters1 may appear puzzling but really it is quite simple4 ,suppose we wish to make a photo-micrograph of a penny stamp and we wish it to be magnified ten diameters1 we should require a large camera for the operation1 but that1 for the moment1 is beside the point4 ,our penny stamp1 magnified ten diameters1 would be equal in area to ten horizontal rows of stamps1 each row containing ten stamps or1 in other words1 it would occupy the same area as one hundred penny stamps4 ,to find the magnification possible with our camera and lens1 extend the camera bellows to the full and set up a foot rule in front of the lens4 ,move the camera from a distance slowly towards the rule till it is sharply focussed1 then carefully measure the distance between the inch lines on the focussing screen2 if the lines are three inches apart we shall be able to make photo-micrographs three times the size of our object and we shall probably desire something better4 ,to obtain a considerably magnified picture we must have a lens of short focal length and a camera with long bellows1 in fact in theory the amount of magnification is only limited by the length of the bellows1 so that an extraordinarily long camera should give us a much magnified picture4 ,we cannot lengthen our bellows without considerable expense1 but we can shorten the focal length of our lens4 ,if we obtain1 at the cost of a few pence1 a convex lens of short focal length1 such as is used in cheap magnifiers we can easily apply it to our camera lens and it will have the effect of shortening its focus4 ,this extra lens can either be fitted in front of our original lens by cutting two inches of cardboard1 of such a size that they will just fit into the lens hood4 ,in the centre of each piece of cardboard1 cut two circles1 slightly smaller in diameter than the diameter of the convex lens4 ,place the lens over the opening in one of the pieces of cardboard and stick the other piece upon it with glue or seccotine4 ,when dry fix the lens in its cardboard holder in the front of the lens hood and repeat the focussing experiment with the foot rule4 ,we shall now obtain a much greater magnification with the same length of bellows1 because the additional lens has shortened the focus of our original lens4 ,probably our camera is fitted with a double lens and it is possible to unscrew the front portion1 in this event our extra lens with its cardboard holder may be fitted inside the front lens up against the diaphragm and the front lens replaced4 ,the result is practically the same whatever the position of the new lens1 but we must be certain that it is convex1 for a concave lens would increase the focal length of the whole and so reduce our magnification4 ,we may find that the amount of enlargement we can now obtain is sufficient for our purpose2 if so we can go ahead and produce photo-micrographs of all the objects we desire4 ,the methods of doing so differ in no way from those employed in taking ordinary photographs and as we are writing about microscopy and not photography in these pages1 there is no need to go into further details4 ,even the experienced photographer1 however1 is liable to overlook one or two important details4 ,the bugbear in all work of this kind1 with low magnifications as well as high1 is vibration4 ,not only is our object magnified but every movement is equally increased4 ,no one should walk across the room while this work is in progress2 in large towns1 trams and heavy motors will ruin many a plate1 in fact it is only when one takes up work of this kind that one realises that one's house is in a perpetual quiver4 ,some enthusiasts work at the dead of night1 others suspend their apparatus on springs and invent all kinds of ingenious devices to overcome these miniature earthquakes4 ,if time is no object1 we have an easy means of still further increasing the magnification4 ,to do so we cut a thin sheet of copper in such a manner that it just fits our lens tube1 in front of the diaphragm4 ,then in the very centre of the copper disc we make a hole with a 8number one0 needle1 the hole is about one twentieth of an inch in diameter4 ,replace the convex lens in its cardboard holder and screw on the front portion of the camera lens4 ,a trial will show that we have considerably increased the magnification but decreased the amount of light admitted by the lens1 therefore we shall probably require an exposure as long as an hour4 ,how about the bugbear vibration during such a long exposure is a natural question to ask4 ,unless the vibration is continuous1 and that is unlikely1 it is less likely to cause trouble during a very long exposure than during a short one1 because it operates during a small proportion of the whole time4 ,all kinds of objects can be depicted with the apparatus we have described4 ,minute shells and insects2 parts of larger insects1 their legs and wings for example2 the feathers of birds2 various rocks1 crystals of all kinds2 small flowers and their seeds2 mosses1 lichens and many kinds of fungus1 in fact their number is limited only by the degree of ingenuity possessed by the photographer4 ,do not suppose that these low-power photo-micrographs are interesting only because of their size1 the enthusiast who makes a collection will discover in his prints hidden beauty of which he had no conception when he looked at the originals4 ,we have seen a very large number of low-power photo-micrographs1 taken with very inexpensive apparatus1 showing the wonderful sculpturing on the wing cases of beetles1 some of them are marvels of design1 yet1 observed with the naked eye1 many of the insects appear to be devoid of ornamentation4 ,the production of high-power photo-micrographs is hardly a subject that can be described in these pages2 the apparatus is costly for1 even if one dispenses with a specially designed micro-photographic camera1 it is necessary to have a good microscope and bellows camera1 for really advanced work4 ,messrs ,swift ,sons supply an excellent fitting1 with which quite satisfactory photo-micrographs may be taken4 ,it consists of a light metal cone1 the more pointed end fits over the upper portion of the microscope tube2 the other end of the cone is provided with ground and plain glass focussing screens and a dark slide4 ,when using this apparatus1 it is first necessary to find and focus our object in the ordinary way1 before attaching the photographic apparatus4 ,having secured our object exactly as we wish it to be depicted and well in the centre of the illuminated circle1 we remove the eyepiece and slip the metal camera over the top of the microscope tube4 ,if now we place the ground glass screen in position1 we can see an image of our object upon it4 ,great attention must be paid to the lighting1 it is necessary that the illumination be perfectly even1 otherwise our negative will be over-exposed in some parts and under-exposed in others4 ,when everything is in order the plain glass screen is substituted for the one of ground glass4 ,on this we shall probably not see any image with the naked eye1 but with the help of a magnifying glass we can see a much finer image than was possible on the ground glass screen4 ,the final focussing is done at this stage and1 having secured as sharp an image as possible1 the focussing screen is removed and the exposure is made4 ,experience alone will teach the length of exposure1 it depends upon the amount and nature of the light1 upon the transparency of the object and also upon its colour4 ,there is no more simple apparatus for taking moderately high-power photo-micrographs2 for more advanced work the micro-telescope and the super-microscope 7see ,chapter ,,xvii7 used with a camera1 will enable the user to obtain pictures of objects magnified as much as five thousand times4 ,,chapter ,,xxi ,,how ,,the ,,glass ,,used ,,in ,,microscopes ,,is ,,made ,having described all the ordinary uses of the microscope and having also insisted that the objectives are the most important part of the instrument1 there are probably many of our readers who may wish to know in what manner this wonderful glass differs from ordinary glass and how it is made4 ,glass has been defined as a substance which1 during its manufacture1 passes from the liquid to the solid state so rapidly that no crystals are formed4 ,usually when solids are melted and then allowed to cool1 they do so with the formation of crystals1 this may be shown in the case of sulphur by melting a little and then allowing it to cool4 ,after a while1 as cooling takes place a solid crust will be formed on the surface of the molten sulphur4 ,if two holes are pierced in the crust and the still liquid sulphur poured out1 it will be found that the sulphur which adhered to the vessel in which the melting took place has formed beautiful needle shaped crystals4 ,a great amount of original work has been done on the subject of glass manufacture and especially on the kind used for optical instruments--as a result there are many kinds of glass differing from one another in physical properties and in chemical composition4 ,although the various chemicals used and their proportions are fairly well standardised1 as the result of long experience1 it is probable that glass is not a definite chemical compound but a mixture1 in which certain of the components act as solvents for the rest4 ,the ordinary glass in use in this country1 apart from specially prepared optical glass1 may be either ,english flint glass1 plate glass or ,bohemian glass4 ,the first named is composed of sand1 potassium carbonate and red lead2 plate glass is made of sand with the carbonates of sodium and calcium1 whilst similar ingredients are used for ,bohemian glass except that carbonate of potassium is substituted for carbonate of sodium4 ,it is chiefly owing to the requirements of optical instrument makers that1 new kinds of glass containing very many previously untried chemicals1 have been produced4 ,as a result glasses are now made with specific gravities varying from #b4e to #e4j1 that is to say the weight of a square inch1 or a square foot or a square yard of glass may weigh anything from two and a half to five times more than a square inch1 foot or yard of water1 according to its composition4 ,before we describe the details of its manufacture let us consider its properties as briefly as possible4 ,at high temperatures it is perfectly fluid and may be poured from vessel to vessel as easily as water2 at lower temperatures it is viscous1 i4e41 semi-fluid and can be rolled with an iron roller as dough is rolled with a rolling pin2 it can be moulded into any desired shape1 blown out into flasks and bottles or drawn out into threads so fine that they may be woven into a fabric4 ,it is a bad conductor of heat and for this reason it is safer to pour very hot liquids into a thin glass vessel than into a thick one4 ,with thick glass the inner layers expand with the heat before the outer layers are even warm and the result is a crack or often absolute fracture4 ,sometimes during manufacture glass vessels which are suddenly cooled will appear satisfactory1 but the particles of glass remain in so high a state of tension that at the slightest touch the vessel will break up into thousands of pieces4 ,on account of this property of glass it must be cooled very slowly indeed2 the process is known as annealing4 ,optical glass unlike most other kinds must be manufactured in thick blocks--some of the large lenses on telescopes are of considerable thickness4 ,all glass for scientific instruments must also be homogeneous1 which our dictionary tells us means of the same kind4 ,to be more explicit each particle of optical glass should be precisely the same in composition and properties as every other particle4 ,in the very early days of manufacture it was difficult to obtain homogeneous pieces of glass and ,guinard1 in the #ahth century1 conceived the idea of stirring the molten glass with a rod of fireclay1 to ensure a thorough mixing of the components4 ,this led to considerable improvement and the method has survived to the present day4 ,the first real advance in the manufacture of optical glass1 was due to the ingenuity of two ,germans1 ,abbe and ,schott1 who lived at ,jena4 ,jena glass became famous for the manufacture of lenses1 so much so that a stupid idea still prevails in many quarters that only the ,germans can make good optical glass4 ,to give them their due it is good but quite recent events have shown the world that the ,britisher can make better4 ,the two ,german scientists used new chemicals in making their glass and they succeeded in producing a substance which possessed hitherto unheard of properties4 ,in what is now known as the older crown and flint glass the dispersion and refraction increased with the density1 that is to say1 the heavier the glass the more it scatters and bends light rays passing through it4 ,with the new methods1 glass is made which scatters the light rays very little1 though bending them considerably and vice versa4 ,the ordinary crown glass is composed of silicates of calcium and sodium or of calcium and potassium or a mixture of both and it is possible to make it colourless and free from defects1 but its optical properties are never so valuable as those of ,jena glass4 ,the most important components of the newer glass are the oxides of ,barium1 ,magnesium1 ,aluminium1 ,zinc and ,boron4 ,good optical glass should be transparent and colourless and1 as we have stated1 it should be homogeneous--the refraction and dispersion of light rays should be identical over all parts of the glass4 ,it should possess no stri1 as they are called4 ,stri may be seen at the edge of a piece of plate glass as little lines just as though the glass had been formed in layers4 ,stri detract from the efficiency of optical glass1 nevertheless1 some very cheap lenses are made of plate glass4 ,bubbles are almost always present in ,jena glass but1 unless they are very numerous they do not appear to render the glass less efficient4 ,hardness and chemical stability are other desirable qualities4 ,most of these high-grade glasses are soft1 as shown by the ease with which they may be scratched2 many of them are not very stable chemically and are easily affected by chemical fumes with the result that their surfaces become covered with a coloured film4 ,with all their drawbacks1 for optical work the newer glasses far excel the older4 ,the manufacture of optical glass is a costly and lengthy process4 ,the chemicals used in its manufacture are selected with the greatest care2 impurities must be guarded against for they would change the composition of the glass and in doing so alter its physical properties on which everything depends4 ,the chemical substances are used either in the form of oxides1 nitrates or carbonates1 for the reason that they are easily decomposed by heat4 ,to assist in the melting of the substances a few fragments of glass of similar composition are added4 ,the crucibles1 in which the chemical components are melted1 are covered so that no fumes from the furnace may gain access to them1 even the chemical composition of the crucibles is carefully tested that no impurities may contaminate the glass4 ,no crucible is ever used more than once and only a single crucible is heated in each furnace1 in order that the temperature may be regulated to a nicety4 ,the actual manufacture is then begun after all these preliminaries have been attended to4 ,a clean dry crucible is heated in a furnace--not the one in which the glass making is to take place--to a dull red heat4 ,then1 with iron tongs1 it is removed to the previously heated glass making furnace and the temperature is raised very gradually4 ,the next stage sees the addition of the well mixed chemicals to the heated crucible1 in small quantities at a time4 ,when the full quantity has been added the crucible contains melted glass full of bubbles1 some of them air bubbles released from the raw materials as they were added and some bubbles of gas given off from the chemicals as they act upon one another4 ,the molten glass is then heated strongly so that it will become perfectly liquid and many of the bubbles will be driven off4 ,to reach this stage may occupy anything from thirty-six to sixty hours and constant attention is necessary during the whole time4 ,the next stage is perhaps the most important in the whole process4 ,after numerous small samples of the molten glass have been taken1 on the end of iron rods1 to see if the air bubbles have been driven off1 the mixture is stirred to render it homogeneous and to eradicate stri4 ,the stirring is carried out by means of a cylinder of fireclay which is first of all heated to the temperature of the molten glass before it is introduced4 ,to the end of the fireclay cylinder a long1 detachable iron handle is fixed so that the man who undertakes the stirring may stand at a distance from the hot furnace4 ,the heat is great and the work of stirring is laborious and for this reason the stirrers are constantly changed4 ,the iron handles must be watched carefully for1 owing to the heat they rust rapidly and should any of the rust fall into the molten glass it would impart to it a colour and render it useless for optical purposes4 ,when stirring begins the glass is liquid as water1 but the stirring is continued during cooling and all the while the glass is gradually becoming more and more solid4 ,during the final stages the operation is hard labour indeed and1 finally1 it is not possible to stir any more1 then the fireclay cylinder is either removed or left in the glass4 ,when the glass has solidified and1 whilst it is still hot the furnace is sealed and allowed to cool very gradually till it has reached the ordinary temperature of its surroundings2 this may take several weeks4 ,when quite cool1 the crucible is removed from the furnace and carefully broken2 then the glass1 which may be in one mass weighing as much as #ajjj lbs41 is freed from particles of fireclay and examined for defects4 ,the next stage consists of moulding and annealing4 ,large pieces of glass are heated till they are just soft1 then they are passed into iron or fireclay moulds designed so that the glass is formed into discs or slabs suitable for grinding by opticians4 ,they are allowed to cool very slowly in the moulds4 ,when the glass is taken from the moulds it is not yet ready to be made into lenses4 ,it is subjected to another and very careful examination1 when all defective parts are cut out4 ,should there be many defects the glass is again heated1 moulded and annealed4 ,from a crucible containing #ajjj lbs4 of molten glass it is unusual to obtain much more than #bjj lbs4 of optically perfect glass1 it is obvious therefore that lenses cannot be cheap4 ,one would naturally imagine that the minute lenses used in microscope objectives should be cheaper in comparison than the larger lenses used for photography or in telescopes1 for it is always more difficult to make minute articles than large ones4 ,as a matter of fact1 even allowing for the greater amount of material used in the larger lenses1 quality being the same in both cases1 they are far more expensive than the smaller microscope lenses2 the reason being that it is exceedingly difficult to obtain a perfect specimen of large size4 ,the difficulty arises not only in the actual manufacture of the glass but in the subsequent operations of cutting1 grinding and polishing when fractures are very liable to occur4 ,from this brief account of the manufacture of optical glass it is clear that a good lens is always worth a high price4 ,its components must be of the purest quality obtainable1 the process of manufacture requires highly skilled labour and it is laborious and exacting work4 ,constant attention is needed from start to finish and much of the glass is never sufficiently good to pass the rigorous tests which it must undergo4 ,lastly1 in the final preparations of the completed lens1 mishaps are frequent4 ,added to all these trials of the lens maker is the one outstanding fact that the process can never be hurried at any stage1 the efficient annealing of optical glass is one of the most important stages in its manufacture4 ,a very full account of the manufacture of optical glass is given in the ,encyclopdia ,britannica1 whence much of our information in this chapter is derived4 ,,chapter ,,xxii ,,the ,,choice ,,and ,,use ,,of ,,apparatus ,,and ,,accessories ,in this1 our concluding chapter1 we propose to give a few hints upon the choice and use of the microscope and its accessories1 to enlighten our readers concerning stains and staining and to add such other information as is likely to be useful1 information which is better supplied in a chapter of its own than scattered about our pages and probably overlooked4 ,the most important question concerns the choice of a microscope4 ,in a book of this nature it is obviously impossible to recommend the wares of any one maker4 ,some firms are celebrated for the good wearing qualities of their instruments1 some for the delicacy--not fragility by the way--of their fine adjustments and our readers must select their maker for themselves4 ,one thing we strongly advise1 be patriotic and select a ,british maker1 it is not only a question of patriotism but of self interest1 for in many respects the ,british instruments lead the world4 ,most of the manufacturers advertise in such papers as ,nature1 they all print excellent catalogues1 a perusal of which may be a useful preliminary4 ,the instrument we select will depend on the use to which we intend to put it and on the length of our purse4 ,perhaps the question of cost will be more important to most people4 ,an elaborate instrument is not a desirable acquisition1 till we are somewhat advanced in our work at anyrate1 and one of the models which most makers call ,students' ,microscopes will do everything we desire4 ,we should have at least two objectives1 three if we can afford them1 a #a inch and a #a_/f inch will enable us to examine everything described in these pages1 except some of the bacteria4 ,if we wish to add a third objective we might select a #b inch one1 for quite low-power work and later we shall probably become the proud possessors of a #a_/ab inch objective1 but this would be of little use to us at first4 ,two eyepieces will complete our optical equipment4 ,a condenser for the stage1 properly known as a substage condenser is an addition which we shall appreciate1 though quite interesting work may be done without it4 ,our other apparatus is inexpensive and comprises1 one or two dissecting knives1 some needles mounted in handles1 a pair of fine scissors1 a pair of small forceps1 a razor1 one or two camel hair brushes1 three or four watch glasses1 slides and cover slips1 and a pipette or two4 ,a pipette1 by the way1 is merely a glass tube pointed at one end and cut off square at the other2 at about its centre it is much wider than at the top or bottom4 ,it is a most useful piece of apparatus for picking up small water animals which we wish to examine4 ,by putting the pointed end of the pipette just over an ,amba1 for example1 and sucking gently at the other end1 we shall draw some water and the animal into the swollen part of the tube4 ,if we then place one finger over the end of the pipette to which we have applied suction we can transfer the contents wherever we wish without it running out1 as soon as we remove our finger the pipette empties itself4 ,the dissecting knives are useful for cutting up specimens before examination1 the mounted needles for teasing them1 that is to say tearing them into fine shreds4 ,the brushes we may use instead of the pipette1 for picking up small objects from water1 or when dry4 ,the watch glasses are useful for examining objects such as sponges1 water fleas1 etc41 under water4 ,they are just as satisfactory for most purposes as the specially constructed zoophyte troughs and1 of course1 very much cheaper4 ,the razor is required for section cutting concerning which we will say a few words4 ,for section cutting1 special razors are sold1 they are heavy as a rule and not hollow ground4 ,many microscopists aver that good sections cannot be cut with a hollow ground razor1 we beg to differ1 however4 ,on this point we would advise our readers to select whichever pattern suits them best2 there is no need to buy an expensive razor1 for our early efforts1 at anyrate1 will quickly dull the cutting edge and there is no advantage in going to much expense in this direction4 ,to cut really good sections is not difficult1 it is a question of knack rather than skill2 having once acquired the knack1 practice will do the rest4 ,the great point is to begin properly1 some people never take the necessary trouble in their early days and1 as a consequence1 they never learn to cut good sections4 ,there is nothing mysterious about the operation1 a section is merely a very thin slice4 ,a good section for examination under the microscope should1 of course1 be so thin that it is transparent2 it should be equally thin everywhere1 not thick in some places and thin in others and it should be cut in the proper direction4 ,the last statement requires a little explanation2 suppose we wish to make a section straight across a stem1 a transverse section it would be called1 then we must see to it that our section is cut straight across1 and not in such a manner that the portion from which the section is cut tapers in the slightest degree4 ,before we begin the actual section cutting we must always trim up our specimen with one of the dissecting knives and not attempt to make the surface level with the razor4 ,as a start1 let us take some moderately fleshy plant stem for we shall find it as easy to cut as anything4 ,our stem must not be woody1 for till we have had a fair amount of practice we shall damage our razor on its hard structures2 it must not be too soft or it will be crushed out of all recognition in our fingers2 it should not be hollow1 for solid stems are always easier to cut4 ,having selected our stem and the spot upon it at which we require a section1 we cut straight across it at that spot with our dissecting knife1 in such a manner that the cut edge is as nearly as possible at right angles to the sides of the stem4 ,a piece two or three inches long is the most comfortable to hold4 ,holding our razor firmly in the right hand we take our specimen in the thumb and index finger of the left hand4 ,place the side of the stem against the first joint of the index finger and slightly bend the tip of the finger round the object4 ,the end of the stem1 from which we propose to cut our section1 should be slightly above the level of the index finger4 ,with the thumb1 the stem is pressed firmly against the first joint of the index finger and the first joint of the thumb must not be bent upwards4 ,this last point is very important1 as we shall see in a moment4 ,from our description the method of holding the stem may seem somewhat cramped2 it should not be so1 however1 and an easy position will help towards success but let it be the correct position4 ,we may play the violin1 in a manner1 without learning the correct method of bowing but we can never become expert violinists unless we hold our bow properly1 in the same way we can never cut really fine sections unless we hold our specimen in the correct way4 ,we now lay our razor along the second joint of the index finger in such a manner that the heel of the razor1 or a point near the heel comes gainst the end of the stem4 ,for the first time we realize the importance of holding our specimen correctly1 for the index finger forms a convenient platform on which to steady the razor4 ,to cut our section1 we1 of course1 press the razor towards us and1 at the same time draw it outwards from heel to toe4 ,we must never attempt to press the razor straight through the specimen1 however soft the latter may be1 we must always draw the razor along1 at the same time as we press it through the specimen4 ,never cut outwards as in sharpening a pencil and never move the razor backwards and forwards as though using a saw4 ,the outward cut will never result in a good section1 a sawing movement will give a section alternately thick and thin4 ,should the section be somewhat tough we may find the razor slip suddenly over its surface1 an event which will impress itself upon us painfully if we have forgotten the injunction not to bend the thumb1 for the certain result of the slip will be the loss of a goodly portion of skin upon one's joint4 ,a straight thumb will be out of the danger zone of a slipping razor4 ,illustration3 ,by the courtesy of ,messrs4 ,f4 ,davidson ,co4 #a4 ,a ,,fly',s ,,eye ,a fly's eye highly magnified1 showing some of the many lenses of which it is composed4 #b4 ,,images ,,seen ,,by ,a ,,fly ,photographs of a statue taken through a fly's eye4 ,instead of seeing one image of an object1 the fly sees as many images as there are lenses in its eyes4 ,having cut a section it is hardly likely that1 at this our first attempt1 it will be good enough to put under the microscope1 so we will continue to cut section after section till we have a dozen or more from these we can select the most transparent for examination4 ,the sections of such material as a stem should be kept moist and to do so we will place them in a watch glass containing water4 ,it is often easier1 also1 to cut our sections if the razor be moistened with water1 at anyrate the moisture prevents the sections from adhering to the razor4 ,the sections should be removed from razor to watch glass and from watch glass to slide1 by means of a brush1 never by means of the fingers4 ,the razor of course1 should be well dried with a soft rag before it is put away2 rust1 besides being unsightly1 ruins the cutting edge4 ,if we are really anxious to cut our own sections1 and every good microscopist does so1 we shall return to the operation again and again1 even cutting objects which we have no desire to examine1 for the sake of the practice4 ,we shall soon reach a stage where our razor will be dulled and require stropping and the efficient stropping of a razor is1 to many people1 a more difficult operation than the cutting of sections4 ,we may point out here1 that all sections are not quite so easy to cut as the one we have taken as our example4 ,some objects are so soft that they need hardening with chemicals before they can be cut1 some are so hard that to attempt to cut them would ruin the edge of the razor1 though it is wonderful what hard substances may be cut when we have had a little experience2 some are so delicate that they must needs be buried in melted wax1 then object and wax are cut together and later the wax is separated from the section4 ,leaves and very small stems may be sectioned by the beginner1 as easily as larger stems4 ,for such objects little sticks of pith are sold as holders4 ,having cut of our piece of leaf from which we wish to derive a section1 we make a slit1 with our dissecting knife1 down the middle of one end of a piece of pith4 ,the piece of leaf is then placed in the slit and by holding the pith at the sides our piece of leaf is held firmly4 ,sections are cut through pith and leaf1 and the two are floated in water1 when the thin slices of pith will float away from the leaf sections4 ,having cut a satisfactory section1 let us proceed to describe the method of making a slide thereof4 ,we will suppose that we do not wish to make a permanent preparation but one for temporary use4 ,a clean slide must be selected1 all through our pages we emphasise the cleanliness of slides1 at or near its centre we put a drop of water and1 lifting it with a brush1 we place our section in the drop of water4 ,if our examination is to be with a low magnification1 we need not use a cover slip1 nevertheless it is worth while to cultivate the habit of using one4 ,the cover slip is not only a protection for our object but for our objective4 ,water you may argue cannot harm the lenses of the objective4 ,perhaps not1 we will not argue the point but1 when the water dries on the objective1 it leaves a certain amount of deposit on the glass and this deposit must be rubbed off4 ,the less often the lenses are rubbed the better for them1 glass especially very highly polished optical glass1 is far more easily scratched than many people imagine and a scratched lens is an inefficient lens4 ,when using high magnifications a cover glass should always cover our object and the same remark applies to objects examined in ,canada ,balsam4 ,this substance is likely to cause serious trouble if it finds its way on to an objective4 ,it must be removed1 that is obvious1 but it sets hard1 it must not be scraped away for fear of damaging the optical glass and1 as it is used to cement the lenses together1 there is the great danger that any solvent used to remove the ,balsam from the face of the objectives1 may also dissolve their setting4 ,our digression may seem somewhat unnecessary1 but the very great importance of keeping all chemicals and even water1 from coming into contact with the lenses of our instrument cannot be insisted upon too strongly4 ,in whatever substance we examine our object1 water1 glycerine or ,balsam1 there is a right and a wrong way of applying the cover slip4 ,it must not be dropped or laid down flat upon the object1 if we do this we shall certainly imprison a number of air bubbles and that must be avoided4 ,one edge of the cover slip must be laid against the edge of the mountant1 as the liquid used for mounting our object is called1 then placing a needle beneath the cover slip it must be gently lowered into position4 ,we shall now find that all air bubbles are driven out as the cover slip is lowered4 ,when we have cut an exceptionally good section or when we have some specially interesting object we may wish to make a permanent slide4 ,the exact method of doing so varies somewhat with the nature of our object and to describe all the methods of mounting microscopic objects permanently would require a book in itself4 ,we will suppose that we wish to make a permanent slide of one of the sections floating in our watch glass of water4 ,the first thing we must do is to get rid of the water with which our section by now is saturated4 ,this may be accomplished by means of alcohol of various strengths1 which we may put into three watch glasses4 ,in the first watch glass we have half pure alcohol and half water2 in the second three-quarters alcohol and one part water2 in the third watch glass pure or absolute alcohol4 ,the section is transferred on a brush to the first watch glass and left there for five minutes1 then to the second watch glass for a similar time and finally to the third watch glass4 ,the mountant may be either ,canada ,balsam or glycerine jelly4 ,should we decide on ,canada ,balsam1 we put a small drop of the substance in the centre of a clean slide1 place one section atop of it and then gently lower a cover slip upon it as already described4 ,then1 without using any force1 the cover slip is pressed down1 but we must not fall into the all too common error of thinking that a thick section can be made thin by pressing upon the cover slip4 ,if we have taken the correct amount of ,canada ,balsam it will just cover the area below the cover slip and no more1 if we have used too much1 it will flow out on all sides and perhaps on the top of the cover slip4 ,a very little experience will teach how big a drop of ,balsam to use4 ,should we decide to use glycerine jelly1 we take a small globule of the jelly on one of our mounted needles and place it in the centre of a clean slide4 ,then we hold the slide a little above a lighted candle1 or even a match will do1 to melt the jelly4 ,directly it is melted the section is placed upon it1 and we proceed as before4 ,whichever mountant we have used1 the slides must be put away out of the dust1 and they must be flat and not placed on edge4 ,in a few days the mountant will set1 and we need take no further precautions with the slides in which ,balsam was used1 but those mounted in glycerine jelly must be ringed1 for the reason that glycerine absorbs moisture from the air and gradually liquifies4 ,the process of ringing is best performed upon a turntable1 which any dealer in microscope accessories will supply4 ,it consists of a circular brass plate which revolves about its centre and to which the slide to be ringed is affixed4 ,a bottle of ringing asphalt and a fine paint brush are essentials4 ,with a little of the asphalt upon our brush1 we revolve the turntable and place the brush against the edge of the cover slip as it revolves1 in such a manner that we paint a narrow rim of asphalt over the junction of cover slip and slide4 ,the asphalt prevents moisture from reaching the glycerine jelly4 ,of course we may ring our slides without making use of a turntable1 but it is not easy to paint a neat ring without mechanical assistance4 ,for square cover slips it is obvious that a turntable is useless4 ,specimens mounted in ,canada ,balsam do not need ringing1 for the ,balsam is unaffected by air or the moisture therein1 when once it has set hard4 ,several firms supply prepared microscope slides1 and it is often useful to know where reliable preparations may be obtained4 ,the slides supplied by ,messrs ,flatters ,garnett ,ltd41 #dji ,oxford ,road1 ,manchester1 are models of what well-made slides should be4 ,it always lends greater interest to the hobby if objects are found and mounted by the microscopist himself4 ,by going out into the fields1 by the pond-side1 or along the shore1 in search of interesting material for examination1 much will be learned of animal and plant habits which even the microscope cannot reveal4 ,some of us1 however1 have neither the opportunity to hunt for our specimens1 nor the time to mount them properly1 and those of us who are so situated will be glad to know where objects may be obtained4 ,apparatus1 useful for students of pond or sea-shore life1 may be obtained from ,messrs ,flatters ,garnett1 who always have a goodly stock of collecting jars1 nets1 c4 ,from the same firm1 also1 may be obtained stains and any of the limited number of chemicals required by the microscopist4 ,we have given a few simple directions for staining in our chapter on ,bacteria4 ,in many cases it is absolutely necessary to have recourse to stains in order to see the structure of the objects we are desirous of examining2 in other cases it is necessary to stain when we wish to know the nature of the various parts of our object4 ,suppose1 for example1 we wish to find out whether a plant section contains starch1 we then add iodine solution1 and if any parts stain deep blue we know at once that starch is present4 ,there are other stains for other plant and animal substances2 stains for woody matter1 stains for fats1 c41 but the art of staining is a science in itself1 and would require many chapters to describe fully4 ,most of the objects described in this book can be studied in the natural state1 but1 even so1 they may be rendered far more beautiful by staining4 ,the method we described for the staining of bacteria does not apply to such objects as plant sections1 c41 and we propose to describe1 as briefly as possible1 how to proceed with such objects4 ,suppose we are examining one of the common pond plants1 ,spirogyra for instance1 and we wish to see whether it contains starch4 ,our specimen is in a slide1 in a drop of water1 and covered by a cover slip4 ,in the first place1 we must obtain some fluffless blotting paper--the ordinary filter papers sold by all chemists are excellent--from it we must cut about half a dozen pieces1 about half an inch by one inch1 the exact size is not important1 and they need not be measured4 ,these we must fold in the centre1 so that they can be made to stand up like an inverted ,v4 ,from our bottle of iodine solution we take a drop of the liquid on the end of a glass rod and place it carefully at one edge of the cover slip1 avoiding allowing any of the solution to flow on to the upper surface of the slip4 ,now1 one of the pieces of blotting paper must be placed upon the opposite side of the slide so that it will stand up2 it must then be moved till it just touches the edge of the cover slip4 ,the blotting paper will absorb the water from beneath the cover slip1 and in doing so the iodine solution will be drawn along to take the place of the water4 ,by proceeding in this manner and replacing the blotting paper with a new piece as it becomes moist1 also replenishing the drop of iodine as it is used up1 we act upon our object with a stronger and stronger solution1 and1 in ,spirogyra1 the object which we took as our example1 we can see beautiful rosettes of starch grains1 arranged at regular intervals along the green bands of chlorophyll4 ,this method of staining may be used in most cases where we merely require a temporary stain2 by reversing the process and drawing water over the object by means of blotting paper1 it may be used in washing sections and parts of plants4 ,for very small objects1 such as starch grains separated from the plants in which they are formed1 the method is hardly suitable1 for they are liable to be drawn along in the stream of liquid and lost4 ,for more permanent staining processes1 we must use our watch glasses1 into which we pour the various liquids necessary for the operation4 ,the precise methods of staining1 the periods during which objects should remain in the staining solution1 and the chemicals used for removing excessive stain vary1 as may be guessed1 according to circumstances4 ,some chemicals act very quickly1 and staining takes place in a few minutes2 others act slowly1 and with them it is necessary to subject our specimens to their action for hours or even days4 ,then again1 it is obvious that large specimens take longer to stain than small ones1 hard objects are not so readily acted upon as soft ones4 ,experience alone will show what is required in various cases4 ,suppose1 for example1 we desire to stain a section in ,carmalum1 a mixture of ,carminic ,acid #a grain1 ,alum #aj grains1 hot distilled water #bjj c4c4 ,we take three watch glasses1 in one we place a few drops of our stain1 in another water1 and in the third alcohol4 ,our section is placed in the watch glass containing the carmalum and is left there for about two minutes1 then with the help of a small brush it is transferred for a similar period to the watch glass containing water1 and finally it is placed in the alcohol4 ,from the last watch glass it may be transferred to glycerine jelly on a slide and mounted as already described2 ,carmalum stains our section a beautiful pink4 ,there is a temptation to buy a large stock of stains of all hues and of varied composition4 ,the temptation should not be allowed to get the better of us4 ,in our early days at anyrate1 we shall do far better if we use but few stains and learn to understand their peculiarities4 ,the most useful selection for the beginner will comprise ,haematoxylin1 ,safranin1 ,eosin1 ,carbol-,fuchsin1 ,methylene ,blue1 and ,carmalum4 ,these should all be obtained ready for use3 this will save errors in compounding1 and1 in certain cases1 will save time2 some of the stains1 ,haematoxylin for example1 are not fit for use till months after they have been mixed with the other ingredients which form the complete stain4 ,frequently when examining small but lively water animals we may feel the necessity of some method of sobering them4 ,all the little organisms1 both plants and animals1 which are provided with the little whip-like structures mentioned so often in our pages1 are difficult to examine whilst they are in motion4 ,there are many substances1 we might add1 which would kill them1 but in doing so we shall nearly always find that they contract to such an extent as to lose all semblance of their natural shape1 and become useless as objects for our microscope4 ,should our inclinations lead us in the direction of much study of these little beings1 we shall do well to keep handy a small bottle of ,rousselet's solution2 it is composed of #b per cent4 solution of hydrochlorate of cocaine1 #c parts2 ,methylated ,spirit1 #a part2 water1 #f parts4 ,any chemist will mix the solution for us4 ,when we have occasion to examine a too lively specimen1 we simply run a drop of the solution under the cover slip1 as described in our remarks on staining with iodine1 and the creature we are examining will abandon its frolics and conveniently remain in a fully expanded state4 ,many of our readers will be anxious to carry their microscopic investigations to a more advanced stage than we have reached in our pages4 ,some will have the advantage of a teacher1 and it is a great advantage to have someone who can show rather than merely explain what should be done2 others not so well placed may like to know a few really useful books which will help them in their work4 8,the ,microscope and its ,revelations10 by ,b4 ,h4 ,dallinger1 is a large and therefore costly work1 but it contains a rare fund of information for the microscopist4 ,smaller and eminently suitable for the general worker is 8,modern ,microscopy10 by ,messrs ,cross ,cole4 ,those who wish to specialize in one of the sciences1 such as ,botany1 ,zoology1 or ,geology1 will find no lack of books dealing with the subject that most appeals to them4 ,for photographers who are also microscopists1 we know of no better books than 8,practical ,principles of ,plain ,photomicrography10 by ,g4 ,west1 or the more advanced 8,handbook of ,photomicrography10 by ,messrs ,hind ,randles4 ,neither books nor teacher will be able to reveal to any of us all the secrets of the microscope4 ,by its means a new world is unfolded before the eyes of mankind1 a world of unlimited possibilities4 ,no man will ever see all that the microscope can show him1 each day some fresh wonder is looked upon for the first time4 ,as a hobby1 microscopy can hardly be excelled4 ,it is a sensible hobby and1 after the initial outlay1 need cost us but a few pence each year4 ,we hear someone say that he prefers an outdoor hobby1 but surely the microscope1 if used intelligently1 will take us out of doors4 ,the search for specimens is one of the attractions of microscopy4 ,as an instrument for the serious worker the microscope compares favourably with any other invention of mankind4 ,think for a moment what we owe to the microscope in a hundred and one walks of life1 and then you will realize the romance attached to the instrument1 and its revelations from the days of ,euclid to the present time4 ,,index ,abbe1 #bhe4 ,aberration1 chromatic1 #dg4 ,aberration1 spherical1 #di4 ,aconite1 #bei4 ,actinophrys ,sol1 #ge4 ,adjustment1 coarse1 #eh2 fine1 #ei4 ,adulteration of food1 #acg4 ,alg1 #bbe4 ,alkaloids1 #add4 ,american water-weed1 #ih4 ,amba ,proteus1 #fg4 ,anatome ,plantarum1 #cb4 ,animal cells1 #afh4 ,animalcule1 bell1 #gj2 protean1 #fg2 slipper1 #fh2 sun1 #ge2 wheel1 #gd4 ,animal fibres1 #bfb4 ,annealing1 #bhd1 #bhi4 ,aphids1 #cf4 ,apparatus1 choice of1 #acg4 ,aristotle1 #cb4 ,bacilli1 #aei4 ,bacillus ,subtilis1 #afj4 ,bacteria1 #cf1 #cg1 #ch1 #aeb2 cultures of1 #afe2 examination of1 #afj2 origin of1 #aee2 size of1 #aef2 splitting of1 #aeg2 staining of1 #afb4 ,barnacle1 #bba4 ,bees1 #cd1 #aie1 #aii4 ,bird's head1 #gf1 #baf4 ,bladderwort1 #ajd4 ,blood1 circulation of1 #bc1 #aga4 ,blood corpuscles1 red1 #cd1 #agj2 white1 #agj4 ,blood crystals1 #agc1 #agd4 ,boreel1 #bj4 ,borel1 #bf4 ,botrydium ,granulatum1 #ib4 ,bread1 #adb4 ,brewing1 #bfj4 ,broomrape1 #ahj4 ,brown1 #ci4 ,browne1 #bd4 ,bubbles in glass1 #bhf4 ,buffalo gnat1 #bja4 ,buffon1 #ci4 ,burning glass1 #ag4 ,butter1 #adh2 renovated1 #adi4 ,caddis fly1 #bjb4 ,calcium carbonate1 #aca1 #bbi4 ,callithamnion ,corymbosum1 #bcg4 ,canada ,balsam1 #cjj4 ,carchesium ,spectabile1 #gb4 ,cells1 #ii4 ,chelifer1 #ca1 #bjj4 ,chemical analysis1 #bdh4 ,chemistry1 #be1 #bjj4 ,chicory1 #ade4 ,chlamydomonas ,angulosa1 #he4 ,chlorophyll1 #ih1 #bbf4 ,cicada1 #bjd4 ,citric acid1 #beh4 ,cladophora ,glomerata1 #ij4 ,classification1 #ci4 ,clay1 #abi4 ,cleavers1 #aaa4 ,club moss1 #acf4 ,cluster cups1 #ahf4 ,cocaine1 #add4 ,cocci1 #aei4 ,cocoa1 #add4 ,coffee1 #add4 ,colonial animals1 #bab4 ,colour of plants1 #ig4 ,comb bearer1 #baj4 ,compound microscope1 #bj2 theory of1 #ea2 to make1 #eb4 ,compressed enteromorpha1 #bbh4 ,condenser1 #fj1 #bib4 ,corallina ,officinalis1 #bbi4 ,coralline1 #bbi4 ,cork1 #ca4 ,corn flour1 #ada4 ,cotton1 #bfb4 ,cover slip1 #fd4 ,crab1 #bbb4 ,cricket1 #bje4 ,cristatella ,mucedo1 #gg4 ,crystal layer1 #bef4 ,crystallization1 #bej4 ,crystals in plants1 #bee4 ,crystals of alum1 #bea2 barium chloride1 #beb2 borax1 #bea2 calcium oxalate1 #bee2 copper sulphate1 #bea2 gold chloride1 #bef2 iron sulphate1 #bea2 potassium chlorate1 #beb2 salt1 #bea2 sugar1 #bea2 washing soda1 #bea4 ,cuprammonia1 #bfc4 ,cuttlefish1 #abb4 ,cuvier1 #ci4 ,cyclops1 #ha4 ,cypris1 #hj4 ,darwin1 #ci4 8,dead ,men's ,ropes10 #bcj2 8,toes10 #baa4 ,delessera ,sanguinea1 #bbi4 ,demodex ,folliculorum1 #agf4 ,depth of focus1 #bdj4 ,descartes1 #ah4 ,desmids1 #he1 #bbe4 ,devil's apron1 #bcj4 ,diaphragm1 #fa2 iris1 #fb4 ,diatoms1 #hb1 #bbe1 #bch4 ,didymograptus1 #ace4 ,digges1 ,l41 #ah1 #bj4 ,digges1 ,t41 #ah4 ,diplococci1 #aei4 ,diplograptus1 #ace4 ,divini1 #ai4 ,dodder1 #ahj4 ,doris1 #bbb4 ,double staining1 #afd4 ,draparnalda ,glomerata1 #ia4 ,drebbel1 #ba4 ,dyes in food1 #aej4 ,earliest microscopes1 #ah4 ,early naturalists1 #cg4 ,ears of insects1 #bje4 ,ectocarpus ,siliculosus1 #bbh1 #bca4 ,egg raft1 #bjb4 ,eggs of frogs1 #abd4 ,engyoscopes1 #ai4 ,entomology1 #aib4 ,euclid1 #ag4 ,euglena ,viridis1 #hh4 ,eyepiece1 #ef2 choice of1 #bib2 ,huygens1 #fc4 ,fallen stars1 #id4 ,feathered hair of bees1 #aii4 ,feathers1 #aah4 ,feelers of beetles1 #aih2 gnats1 #aih2 moths1 #aih4 ,ferments1 #aed4 ,finger prints1 #cc4 ,flax1 #bfb4 ,fleas1 #bc1 #ca1 #cg2 water1 #gi4 ,flint1 #abi4 ,flour1 #bgb4 ,flowers1 grass1 #ajf4 ,focus of lens1 #bge4 ,food adulteration1 #acg4 ,foot of butterfly1 #aig2 fly1 #ca1 #aih2 louse1 #aih4 ,foraminifera1 #cj1 #ace4 ,formic acid1 #beh4 ,fossils1 #ci1 #acj1 #acd4 ,fringe wings1 #bjg4 ,fruits of burdock1 #aaa2 dandelion1 #aaa2 goosegrass1 #aaa2 groundsel1 #aaa2 thistle1 #aaa4 ,fusion tests1 #bec4 ,galileo1 #ba1 #bb4 ,geology1 #abe4 ,germination1 #cb4 ,glass1 #bhb2 ,bohemian1 #bhc2 crown1 #bhe2 flint1 #bhc1 #bhe2 ,jena1 #bhe2 optical1 #bhd2 plate1 #bhc4 ,glucose1 #aea4 ,gluten strings1 #bgc4 ,glycerine jelly1 #cja4 ,gordon1 #ag4 ,gossypium1 #bfb4 ,graaf1 #ai4 ,granite1 #abf4 ,graptolites1 #ace4 ,grasshopper1 #bje4 ,grew1 #cc4 ,guinard1 #bhd4 ,hair1 #aja1 #bfa1 #bfg2 root1 #ajc4 ,hardness of glass1 #bhf4 ,harvestmen1 #aae4 ,hay ,bacillus1 #afj4 ,hemp1 #bfd4 ,hodierna1 #bd4 ,honey1 #adi4 ,hooke1 #ai1 #bi1 #ce1 #bae1 #baf4 ,horsetails1 #aaj1 #acf4 ,house fly1 #be1 #aie1 #aih4 ,human blood1 #afi4 ,humboldt1 #ci4 ,hydra1 #cg1 #fi1 #ace1 #bji1 #bae4 ,hydrodictyon ,reticulatum1 #ic4 ,image1 inverted1 #ef2 real1 #eb1 #ee2 virtual1 #eb1 #ec1 #ee4 ,infection1 #bf4 ,infusorians1 #cf4 ,insect transformation1 #cd4 ,insectivorous plants1 #ajd4 ,insectorum ,theatrum1 #cd4 ,intestinal enteromorpha1 #bbh4 ,jute1 #bfd4 ,killing specimens1 #cjf4 ,kircher1 #bc1 #bf1 #cf4 ,laminaria1 #bcj4 ,leaf1 bloom1 #aja2 cabbage1 #ajj2 folded1 #aja2 hair1 #aja2 heather1 #aja2 iris1 #ajj2 marram grass1 #aja2 rolled1 #aja2 structure1 #ajj2 veins1 #ajc2 water lily1 #ajj4 ,leeuwenhoek1 #ai1 #ce1 #cf1 #cg1 #ch4 ,lenses1 perfect1 #di2 shapes of1 #dd4 ,lice1 #bc1 #ca1 #aih2 water1 #gi2 wood1 #gi1 #ace4 ,light1 #dj2 rays1 #da4 ,limestone1 #aca4 ,linen1 #bfd4 ,linnus1 #ci4 ,liver fluke1 #cc1 #gf1 #ahh4 ,lophopus ,crystallinus1 #gf4 ,lung books1 #aaf4 ,magnetite1 #abi4 ,magnification1 to increase1 #fd4 ,malaria1 #agc4 ,malpighi1 #bc1 #ca1 #cb4 ,marble bleb1 #baj4 ,mealy bug1 #bjf4 ,mechanical stage1 #fe4 ,medical work1 #bf4 ,mercer1 #bfc4 ,mercerised cotton1 #bfc4 ,mermaid's fingers1 #baa4 ,miall1 #cg4 ,mica1 #abf1 #abi4 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,seeds1 #aaa2 of campion1 #ahj2 clover1 #agi2 corn buttercup1 #ahj2 cornflower1 #ahj2 evening primrose1 #ahj2 grass1 #agi2 larkspur1 #ahj2 rib wort plantain1 #ahj2 spurrey1 #ahj2 wild carrot1 #ahj4 ,seed testing1 #agh4 ,seneca1 #ag4 ,serpula1 #bba4 ,shale1 #abi4 ,shell binder1 #bba4 ,shells1 #abb1 #abi4 ,shoddy1 #bfi4 ,shrimp1 fresh water1 #gi4 ,silk1 #bgj2 artificial1 #bgb2 glue1 #bgj2 tussore1 #bga2 weed1 #ij2 worm1 #cb4 ,silver fish1 #ca4 ,simulium1 #bja4 ,slate1 #abi4 ,sleeping sickness1 #agc4 ,slides1 #fd4 ,slide making1 #bie2 mounting1 #cjj2 ringing1 #cja4 ,slugs1 #abc4 ,smuts1 #ahd4 ,snail1 #cd1 #ce1 #cg1 #abc2 rasping organ of1 #abc2 water1 #gg4 ,solution tests1 #bed4 ,spicules of ,doris1 #bbb2 sponge1 #acb1 #ach4 ,spider1 #ca1 #cg1 #aab2 crab1 #aae2 drassid1 #aad2 garden1 #aab2 house1 #aac2 wolf1 #aad2 zebra1 #aad4 ,spinnerets1 #aaf4 ,spirilla1 #aei4 ,spirogyra1 #id1 #bbe4 ,sponge1 bath1 #gb2 pond1 #gb2 purse1 #gc2 river1 #gb2 spicules1 #acb1 #ach4 ,spongia ,coalita1 #bac4 ,spores1 #aji1 #afb1 #ahb4 ,stains1 #bia1 #cjh4 ,stalactites1 #acb4 ,staphylococci1 #aei4 ,starch1 #aci2 arrowroot1 #ada2 banana1 #adb2 barley1 #ada2 bean1 #adb2 lentil1 #adb2 maize1 #ada2 pea1 #adb2 potato1 #adj2 rice1 #ada2 rye1 #ada2 sago1 #adb2 spurge1 #adb2 tapioca1 #adb2 to stain1 #adb4 ,star fish1 #bac4 ,stinging darts1 #bji2 hairs1 #cb1 #ajb4 ,stomata1 #cb4 8,stops10 #fa4 ,streptococci1 #aei4 ,stri in glass1 #bhf4 ,strychnine1 #bei4 ,sundew1 #ajd4 ,swammerdam1 #cc4 ,synapta ,inhrens1 #bai4 ,tadpole1 #cd1 #abd4 ,tangle1 #bcj2 fingered1 #bcj4 ,tea1 #adc4 ,telescope1 #bj4 ,theine1 #add4 ,thrips1 #bjg4 ,trichinella ,spiralis1 #agf4 ,trilobites1 #ace4 ,ulva ,lactuosa1 #bbh4 ,vaucheria ,sessilis1 #ia4 ,vegetable fibres1 #bfa4 ,vinci1 #ah4 ,vinegar eels1 #ca4 ,vitrea muscaria1 #ai2 publicaria1 #ai4 ,volvox1 #cg1 #hg1 #bbe4 ,vorticella1 #ga4 ,water net1 #ic4 ,water testing1 #adf4 ,wings of bees1 #aie2 butterflies1 #aic2 dragonflies1 #aid2 flies1 #aid2 gnats1 #aid4 ,wool1 #bfh2 fat1 #bfh4 ,wrack1 bladder1 #bbh1 #bcc1 #bcf2 channelled1 #bcc1 #bcd2 flat1 #bcc2 knobbed1 #bcd2 notched1 #bcd4 ,yeast1 #cf4 ,zacharias1 #bj1 #ba1 #bb4 ,zoospores1 #bca4 99 99 99 99 99 ,seeley1 ,service ,co ,,ltd ,founded #agie ,,the ,,new ,,art ,,library 8,the admirable ,new ,art ,library40--,connoisseur4 ,,new ,,volume ,,the ,,painter',s ,,methods ,,materials ,by ,professor ,a4 ,p4 ,,laurie1 ,m4,a41 ,d4,,sc41 ,f4,r4,s4,e41 ,,hon4 ,r4,s4,a41 ,professor of ,chemistry to the ,royal ,academy4 ,with #ej illus4 #bas4 nett4 ,,landscape4 ,by ,,adrian ,,stokes1 ,r4,a4 #aes4 nett4 ,,etching4 ,by ,e4 ,s4 ,,lumsden4 #bjh illus4 #bas4 nett4 ,,drawing4 ,by ,,harold ,,speed4 #if illus4 #ajs4 #f;d4 nett4 ,,oil ,,painting4 ,s4 ,j4 ,,solomon1 ,r4,a4 #hj illus4 #ajs4 #f;d4 nett4 ,,anatomy4 ,sir ,,alfred ,d4 ,,fripp4 #aei illus4 #aes4 nett4 ,,modelling ,,sculpture4 ,a4 ,,toft4 #aai illus4 #aes4 nett4 ,,water ,,colour4 ,a4 ,w4 ,,rich4 #fj illus4 #ajs4 #f;d4 nett4 ,,perspective4 ,r4 ,,vicat ,,cole4 #dgb illus4 #aes4 nett4 ,,anatomy ,,of ,,trees4 ,r4 ,v4 ,,cole4 #ejj illus4 #aes4 nett4 ,illustration3 ,illustration from ,speed's 8,drawing40 99 99 99 99 99 ,illustration3 ,a ,,marine ,,reptile4 ,from 8,geology of ,to-day40 ,,science ,,of ,,to-,,day ,,series ,,latest ,,volume #af4 ,,wireless ,,of ,,to-,,day4 ,by ,c4 ,r4 ,,gibson1 ,,ll4,d41 ,w4 ,b4 ,,cole4 #fs4 nett each ,vol4 ,,some ,,of ,,the ,,volumes4 #a4 ,,electricity ,,of ,,to-,,day4 ,c4 ,r4 ,,gibson1 ,,ll4,d41 ,f4,r4,s4,e4 #b4 ,,astronomy ,,of ,,to-,,day4 ,,cecil ,g4 ,,dolmage1 ,m4,a41 ,d4,c4,l41 ,,ll4,d41 ,f4,r4,a4,s4 #c4 ,,scientific ,,ideas ,,of ,,to-,,day4 ,c4 ,r4 ,,gibson1 ,f4,r4,s4,e4 #d4 ,,botany ,,of ,,to-,,day4 ,prof4 ,g4 ,f4 ,,scott ,,elliot1 ,m4,a4 #f4 ,,engineering ,,of ,,to-,,day4 ,t4 ,w4 ,,corbin4 #i4 ,,photography ,,of ,,to-,,day4 ,prof4 ,h4 ,,chapman ,,jones4 #aj4 ,,submarine ,,engineering4 ,c4 ,w4 ,,domville-,,fife4 #aa4 ,,geology ,,of ,,to-,,day4 ,prof4 ,j4 ,w4 ,,gregory1 ,f4,r4,s4 #ab4 ,,aircraft ,,of ,,to-,,day4 ,maj4 ,c4 ,c4 ,,turner4 #ad4 ,,animal ,,ingenuity4 ,c4 ,a4 ,,ealand1 ,m4,a4 #ae4 ,,chemistry ,,of ,,to-,,day4 ,p4 ,g4 ,,bull1 ,m4,a4 99 99 99 99 99 ,,the ,,things ,,seen ,,series ,cloth1 #cs4 #f;d4 nett4 ,leather1 #es4 nett4 8,dainty and attractive little books40--,daily ,post4 ,,new ,,volumes #bf4 ,,things ,,seen ,,in ,,switzerland 7,in ,summer74 ,,douglas ,,ashby4 #bg4 ,,things ,,seen ,,in ,,the ,,pyrenees4 ,,capt4 ,,leslie ,,richardson4 #bh4 ,,things ,,seen ,,in ,n4 ,,wales4 ,w4 ,t4 ,,palmer4 #bi4 ,,things ,,seen ,,at ,,the ,,tower ,,of ,,london4 ,h4 ,,plunket ,,woodgate4 ,,already ,,issued ,,in ,,this ,,series ,,things ,,seen ,,in #a4 ,,japan4 ,,clive ,,holland4 #b4 ,,china4 ,j4 ,r4 ,,chitty4 #c4 ,,egypt4 ,e4 ,l4 ,,butcher4 #d4 ,,holland4 ,c4 ,e4 ,,roche4 #e4 ,,spain4 ,g4 ,,hartley4 #f4 ,,north ,,india4 ,t4 ,l4 ,,pennell4 #g4 ,,venice4 ,,lonsdale ,,ragg4 #i4 ,,palestine4 ,a4 ,g4 ,,freer4 #aj4 ,,oxford4 ,n4 ,j4 ,,davidson4 #aa4 ,,sweden4 ,,barnes ,,steveni4 #ab4 ,,london4 ,a4 ,h4 ,,blake4 #ac4 ,,florence4 ,e4 ,,grierson4 #ad4 ,,italian ,,lakes4 ,l4 ,,ragg4 #ae4 ,,riviera4 ,l4 ,,richardson4 #af4 ,,normandy ,,brittany4 ,,clive ,,holland4 #ag4 ,,constantinople4 ,a4 ,,goodrich-,,freer4 #ah4 ,,edinburgh4 ,e4 ,,grierson4 #ai4 ,,switzerland ,,in ,,winter4 ,c4 ,w4 ,,domville-,,fife4 #bj4 ,,english ,,lakes4 ,w4 ,t4 ,,palmer4 #ba4 ,,paris4 ,,clive ,,holland4 #bb4 ,,rome4 ,a4 ,g4 ,,mackinnon1 ,m4,a4 #bc4 ,,norway4 ,s4 ,c4 ,,hammer1 ,m4,a4 #bd4 ,,shakespeare',s ,,country4 ,,clive ,,holland4 #be4 ,,canada4 ,j4 ,e4 ,,ray4 99 99 99 99 99 ,,the ,,ian ,,hardy ,,series ,by ,commander ,e4 ,,hamilton ,,currey1 ,r4,n4 ,with ,coloured ,illustrations4 ,extra ,crown #hvo4 #es4 nett each4 ,each of the volumes in the ,ian ,hardy ,series is a complete story by itself1 but each describes another stage of the adventurous life of the delightful young rascal who is their hero4 ,,vols4 ,i ,,to ,,iv ,,of ,,the ,,ian ,,hardy ,,series4 ,,ian ,,hardy1 ,,naval ,,cadet4 8,an ideal gift book for a boy1 for it is utterly devoid of the milksop piffle in which such stories usually indulge4 ,a whole budget of mirth and adventure40--,manchester ,courier4 ,,ian ,,hardy1 ,,midshipman4 8,combines as much adventure as the most spirited of young readers could possibly wish for1 with a faithful picture of what a middy's life may be when he is lively and as plucky as ,ian0--,glasgow ,herald4 ,,ian ,,hardy1 ,,senior ,,midshipman4 8,it is no exaggeration to say that ,commander ,currey bears worthily the mantle of ,kingston and ,marryat40--,manchester ,courier4 ,,ian ,,hardy1 ,,fighting ,,the ,,moors4 8,commander ,currey is becoming a serious rival to ,kingston40--,yorkshire ,observer4 ,illustration3 ,specimen ,binding4 ,a ,,stirring ,,story ,,for ,,boys4 ,,jack ,,scarlett1 ,,sandhurst ,,cadet4 ,by ,major ,,alan ,m4 ,,boisragon4 ,coloured ,illustrations4 #es4 nett4 8,a dashing youth who has a good time1 but emerges from his training with a good character40--,manchester ,courier4 99 99 99 99 99 ,,the ,,library ,,of ,,romance ,lavishly ,illustrated4 ,ex4 ,crown #hvo4 #fs4 nett each volume4 8,splendid volumes40--,the ,outlook4 8,gift books whose value it would be difficult to over-estimate40--,the ,standard4 8,this series has now won a considerable and well-deserved reputation40--,the ,guardian4 #dj4 ,,the ,,romance ,,of ,,our ,,wonderful ,,world4 ,p4 ,j4 ,,risdon4 ,illustration3 ,,quelling ,a ,,mutiny4 ,from 8,the ,romance of ,piracy40 ,,the ,,romance ,,of-- ,,submarine ,,engineering4 ,t4 ,w4 ,,corbin4 ,,modern ,,exploration4 ,a4 ,,williams1 ,f4,r4,g4,s4 ,,modern ,,invention4 ,a4 ,,williams4 ,,modern ,,engineering4 ,a4 ,,williams4 ,,animal ,,world4 ,e4 ,,selous4 ,m4 ,,locomotion4 ,a4 ,,williams4 ,,electricity4 ,c4 ,r4 ,,gibson1 ,,ll4,d41 ,f4,r4,s4,e4 ,,mod4 ,,mechanism4 ,a4 ,,williams4 ,,insect ,,life4 ,e4 ,,selous4 ,,mining4 ,a4 ,,williams1 ,b4,a4 ,,plant ,,life4 ,prof4 ,,scott ,,elliot4 ,,bird ,,life4 ,,john ,,lea1 ,m4,a4 ,,photography4 ,c4 ,r4 ,,gibson4 ,,chemistry4 ,prof4 ,,philip1 ,f4,r4,s4 ,,manufacture4 ,c4 ,r4 ,,gibson4 ,,early ,,british ,,life4 ,by ,prof4 ,,scott ,,elliot1 ,m4,a41 ,b4,,sc4 ,,geology4 ,e4 ,s4 ,,grew1 ,m4,a4 ,,animal ,,arts ,,crafts4 ,,john ,,lea1 ,m4,a4 ,,early ,,exploration4 ,a4 ,,williams1 ,f4,r4,g4,s4 ,,missionary ,,heroism4 ,dr4 ,,lambert1 ,m4,a4 ,,mighty ,,deep4 ,a4 ,,giberne4 ,,polar ,,exploration4 ,g4 ,f4 ,,scott4 ,,savage ,,life4 ,prof4 ,s4 ,,elliot4 ,,sieges4 ,e4 ,,gilliat1 ,m4,a4 ,,the ,,ship4 ,,keble ,,chatterton4 ,,astronomy4 ,h4 ,,macpherson4 ,,scientific ,,discovery4 ,c4 ,r4 ,,gibson1 ,,ll4,d41 ,f4,r4,s4,e4 ,,piracy4 ,lieut4 ,k4 ,,chatterton4 ,,war ,,inventions4 ,t4 ,w4 ,,corbin4 ,,commerce4 ,h4 ,o4 ,,newland4 ,,microscope4 ,c4 ,a4 ,,ealand1 ,m4,a4 ,,railways4 ,t4 ,w4 ,,corbin4 ,,coal4 ,c4 ,r4 ,,gibson1 ,f4,r4,s4,e4 ,,sea ,,rovers4 ,e4 ,k4 ,,chatterton1 ,b4,a4 ,,lighthouses ,,lifeboats4 ,t4 ,w4 ,,corbin4 99 99 99 99 99 ,,science ,,for ,,children ,illustration3 ,specimen ,binding4 ,popular ,science for ,young ,children of #h to #ad4 ,each #es4 nett4 8,among writers on science for boys1 easily the most skilful is ,mr4 ,charles ,gibson40--,the ,nation4 ,,new ,,volume ,,machines ,,how ,,they ,,work4 ,c4 ,r4 ,,gibson1 ,,ll4,d41 ,f4,r4,s4,e4 ,,earlier ,,volumes ,,photography ,,its ,,mysteries4 ,c4 ,r4 ,,gibson1 ,f4,r4,s4,e4 ,,the ,,great ,,ball ,,on ,,which ,,we ,,live4 ,c4 ,r4 ,,gibson1 ,f4,r4,s4,e4 8,an admirable introduction to about half a dozen of the most recondite sciences without going beyond the comprehension of any intelligent child40--,scotsman4 ,,our ,,good ,,slave ,,electricity4 ,c4 ,r4 ,,gibson1 ,f4,r4,s4,e4 8,reads like a fairy tale1 yet every word is true40--,dundee ,courier4 ,,the ,,stars ,,and ,,their ,,mysteries4 ,c4 ,r4 ,,gibson1 ,f4,r4,s4,e4 ,,war ,,inventions ,,and ,,how ,,invented4 ,c4 ,r4 ,,gibson1 ,f4,r4,s4,e4 ,,chemistry ,,and ,,its ,,mysteries4 ,c4 ,r4 ,,gibson1 ,f4,r4,s4,e4 ,,great ,,inventions ,,how ,,they ,,were ,,invented4 ,c4 ,r4 ,,gibson1 ,f4,r4,s4,e4 99 99 99 99 99 ,,the ,,wonder ,,library ,particularly handsome ,gift ,books for ,young ,people4 ,illustrated4 #cs4 nett each4 ,,new ,,volume ,,the ,,wonders ,,of ,,mining4 ,a4 ,,williams1 ,b4,a41 ,f4,r4,g4,s4 ,illustration3 ,binding of the ,wonder ,library4 ,,some ,,of ,,the ,,earlier #ah ,,vols4 ,,are3-- #a4 ,,the ,,wonders ,,of ,,asiatic ,,exploration4 ,a4 ,,williams1 ,f4,r4,g4,s4 #b4 ,,the ,,wonders ,,of ,,mechanical ,,ingenuity4 ,a4 ,,williams1 ,b4,a4 #c4 ,,the ,,wonders ,,of ,,animal ,,ingenuity4 ,h4 ,,coupin1 ,d4,,sc41 and ,,john ,,lea1 ,m4,a4 #d4 ,,the ,,wonders ,,of ,,the ,,plant ,,world4 ,prof4 ,g4 ,f4 ,,scott ,,elliot4 #e4 ,,the ,,wonders ,,of ,,the ,,modern ,,railway4 ,t4 ,w4 ,,corbin4 #f4 ,,the ,,wonders ,,of ,,the ,,insect ,,world4 ,,edmund ,,selous4 #g4 ,,the ,,wonders ,,of ,,modern ,,engineering4 ,a4 ,,williams1 ,b4,a4 #h4 ,,the ,,wonders ,,of ,,bird ,,life4 ,,john ,,lea1 ,m4,a4 #i4 ,,the ,,wonders ,,of ,,modern ,,chemistry4 ,prof4 ,j4 ,c4 ,,philip1 ,f4,r4,s4 #aj4 ,,the ,,wonders ,,of ,,electricity4 ,c4 ,r4 ,,gibson4 #aa4 ,,the ,,wonders ,,of ,,modern ,,invention4 ,a4 ,,williams1 ,b4,a4 #ab4 ,,the ,,wonders ,,of ,,modern ,,astronomy4 ,,hector ,,macpherson1 ,m4,a4 #ac4 ,,the ,,wonders ,,of ,,savage ,,life4 ,prof4 ,,scott ,,elliot1 ,m4,a41 ,b4,,sc4 #ah4 ,,the ,,wonders ,,of ,,scientific ,,discovery4 ,c4 ,r4 ,,gibson1 ,f4,r4,s4,e4 99 99 99 99 99 ,,the ,,daring ,,deeds ,,library ,with many ,illustrations in ,colours4 #es4 nett each4 #i4 ,,daring ,,deeds ,,of ,,great ,,buccaneers4 ,,norman ,j4 ,,davidson1 ,b4,a4 7,oxon47 ,,daring ,,deeds ,,of #a4 ,,famous ,,pirates4 ,lieut4 ,commdr4 ,,keble ,,chatterton1 ,b4,a47,oxon47 #b4 ,,trappers ,,and ,,hunters4 ,e4 ,,young1 ,b4,,sc4 #c4 ,,indian ,,mutiny4 ,,edward ,,gilliat1 ,m4,a4 #d4 ,,dark ,,forests4 ,h4 ,w4 ,g4 ,,hyrst4 #e4 ,,great ,,pathfinders4 ,e4 ,,sanderson1 ,m4,a4 #f4 ,,great ,,mountaineers4 ,,richd4 ,,stead1 ,b4,a4 #g4 ,,polar ,,explorers4 ,g4 ,,firth ,,scott4 #h4 ,,among ,,wild ,,beasts4 ,h4 ,w4 ,g4 ,,hyrst4 99 99 99 99 99 ,,the ,,library ,,of ,,adventure ,with ,jackets in #c colours ,illustrations4 #fs4 n4 each4 ,,latest ,,volume #aa4 ,,adventures ,,of ,,missionary ,,explorers4 ,dr4 ,pennell1 ,grenfell1 ,barbrooke ,grubb1 ,bishop ,bompas1 c4 ,r4 ,m4 ,a4 ,,ibbotson4 8,of all books on ,missions we have read this is the most fascinating40--,dundee ,courier4 ,,recently ,,issued ,,in ,,this ,,series ,,adventures ,,on ,,the #a4 ,,high ,,mountains4 ,r4 ,,stead1 ,b4,a41 ,f4,r4,h4,s4 #b4 ,,great ,,forests4 ,h4 ,w4 ,g4 ,,hyrst4 #c4 ,,great ,,deserts4 ,h4 ,w4 ,g4 ,,hyrst4 #d4 ,,great ,,rivers4 ,r4 ,,stead1 ,b4,a41 ,f4,r4,h4,s4 #e4 ,,wild ,,beasts4 ,h4 ,w4 ,g4 ,,hyrst4 #f4 ,,high ,,seas4 ,r4 ,,stead1 ,b4,a4 #g4 ,,arctic ,,regions4 ,h4 ,w4 ,g4 ,,hyrst4 #h4 ,,red ,,indians4 ,h4 ,w4 ,g4 ,,hyrst4 #i4 ,,trappers ,,hunters4 ,e4 ,,young1 ,b4,,sc4 #aj4 ,,southern ,,seas4 ,r4 ,,stead1 ,b4,a4 99 99 99 99 99 ,,seeley',s ,,missionary ,,lives ,,for ,,children4 ,with ,covers in #d ,colours4 ,illustrated4 ,price #as4 nett4 ,illustration 8,with attractive coloured covers1 well written1 and at the wonderfully low price of one shilling4 ,will bring delight to the boys and girls who get them40--,missionary ,herald4 ,,barbrooke ,,grubb ,,of ,,paraguay4 ,c4 ,t4 ,,bedford4 ,,moffat ,,of ,,africa4 ,n4 ,j4 ,,davidson4 ,,arnot ,,of ,,africa4 ,,nigel ,b4 ,m4 ,,grahame4 ,,bishop ,,bompas ,,of ,,the ,,frozen ,,north4 ,,nigel ,b4 ,m4 ,,grahame1 ,b4,a4 ,,livingstone ,,of ,,africa4 ,c4 ,t4 ,,bedford4 ,,john ,,williams ,,of ,,the ,,south ,,sea ,,islands4 ,n4 ,j4 ,,davidson4 ,,hannington ,,of ,,africa4 ,,nigel ,b4 ,m4 ,,grahame1 ,b4,a4 ,,pennell ,,of ,,the ,,indian ,,frontier4 ,,norman ,j4 ,,davidson1 ,b4,a47,oxon74 ,,judson ,,of ,,burma4 ,,nigel ,b4 ,m4 ,,grahame1 ,b4,a4 99 99 99 99 99 ,,the ,,prince',s ,,library ,handsome ,gift ,books for ,young ,people4 ,many ,illustrations4 #ds4 #f;d4 nett each4 ,,latest ,,volume #ag4 ,,the ,,count ,,of ,,the ,,saxon ,,shore4 ,prof4 ,a4 ,j4 ,,church4 ,,recently ,,issued #a4 ,,last ,,of ,,the ,,whitecoats4 ,g4 ,i4 ,,whitham4 #b4 ,,diana ,,polwarth1 ,,royalist4 ,j4 ,,carter4 #c4 ,,the ,,fall ,,of ,,athens4 ,prof4 ,,church1 ,m4,a4 #d4 ,,the ,,king',s ,,reeve4 ,,edward ,,gilliat1 ,m4,a4 #e4 ,,cabin ,,on ,,the ,,beach4 ,m4 ,e4 ,,winchester4 #f4 ,,the ,,captain ,,of ,,the ,,wight4 ,f4 ,,cowper4 #g4 ,,grimm',s ,,fairy ,,tales4 ,new ,translation4 #h4 ,,the ,,wolf',s ,,head4 ,,edward ,,gilliat1 ,m4,a4 #i4 ,,andersen',s ,,fairy ,,tales4 #aj4 ,,caedwalla4 ,,frank ,,cowper4 #aa4 ,,the ,,arabian ,,nights' ,,entertainments4 #ab4 ,,robinson ,,crusoe4 ,,daniel ,,defoe4 #ac4 ,,the ,,vicar ,,of ,,wakefield4 ,,goldsmith4 #ad4 ,,cranford4 ,mrs4 ,,gaskell4 #ae4 ,,patriot ,,and ,,hero4 ,prof4 ,,church4 #af4 ,,ministering ,,children4 ,,charlesworth4 99 99 99 99 99 ,,heroes ,,of ,,the ,,world ,,library ,each ,volume fully ,illustrated4 ,ex4 ,crown #hvo4 #fs4 nett4 ,illustration3 ,,the ,,storming ,,of ,,jhansi4 ,from 8,heroes of the ,indian ,mutiny40 ,,latest ,,volume #i4 ,,heroes ,,of ,,the ,,indian ,,mutiny4 ,,edward ,,gilliat1 ,m4,a41 sometime ,master at ,harrow ,school4 ,with ,full-page ,illustrations4 8,a capital book4444 ,full of stories of heroic deeds1 intrepidity1 and determination performed in the face of fearful odds40--,the ,field4 ,,recently ,,issued ,,in ,,this ,,series4 ,,heroes ,,of #a4 ,,missionary ,,enterprise4 ,,claud ,,field1 ,m4,a4 #b4 ,,pioneering4 ,,edgar ,,sanderson1 ,m4,a4 #c4 ,,missionary ,,adventure4 ,,canon ,,dawson1 ,m4,a4 #d4 ,,modern ,,crusades4 ,e4 ,,gilliat1 ,m4,a4 #e4 ,,modern ,,india4 ,e4 ,,gilliat1 ,m4,a4 #f4 ,,the ,,elizabethan ,,age4 ,e4 ,,gilliat1 ,m4,a4 #g4 ,,modern ,,africa4 ,e4 ,,gilliat1 ,m4,a4 #h4 ,,the ,,scientific ,,world4 ,c4 ,r4 ,,gibson1 ,f4,r4,s4,e4 99 99 99 99 99 ,,the ,,dick ,,valliant ,,series ,by ,lieut4-,commander ,,john ,,irving1 ,r4,n4 ,with ,coloured ,illustrations4 ,extra ,crown #hvo4 #es4 nett4 ,,dick ,,valliant1 ,,naval ,,cadet4 ,a stirring story of the life adventures of a naval cadet in peace war4 ,dick ,valliant is the first volume of a new series of books for boys which will deal with the most exciting interesting naval incidents of the ,great ,war4 ,it will be followed in #aibh by the second volume entitled ,,dick ,,valliant ,,in ,,the ,,dardarnelles4 ,a new volume will be added each year thereafter4 99 99 99 99 99 ,,the ,,pink ,,library ,books for ,boys ,girls4 ,illustrated4 #bs4 #f;d4 nett each4 ,,new ,,volume #bi4 ,,the ,,pirate4 ,,capt4 ,,marryat4 ,,some ,,of ,,the #bi ,,vols4 ,,in ,,this ,,series #a4 ,,lionhearted4 ,canon ,e4 ,c4 ,,dawson4 #c4 ,,to ,,the ,,lions4 ,prof4 ,a4 ,j4 ,,church4 #i4 ,a ,,greek ,,gulliver4 ,a4 ,j4 ,,church4 #ae4 ,,missionary ,,heroes ,,in ,,asia4 ,j4 ,g4 ,,lambert1 ,m4,a41 ,d4,d4 #af4 ,,little ,,women4 ,l4 ,m4 ,,alcott4 #ag4 ,,good ,,wives4 ,l4 ,m4 ,,alcott4 #ah4 ,,missionary ,,heroes ,,in ,,africa4 ,j4 ,g4 ,,lambert1 ,d4,d4 #ba4 ,,grimm',s ,,fairy ,,tales4 ,a ,new ,translation4 #bb4 ,,what ,,katy ,,did ,,at ,,home4 ,,susan ,,coolidge4 #bh4 ,,missionary ,,heroines ,,in ,,india4 ,canon ,,dawson4 ,illustration3 ,,boxes ,,from ,,home4 ,from 8,what ,katy ,did40 99 99 99 99 99 ,,missionary ,,biographies--a new series ,with many ,illustrations and a ,frontispiece in ,colours1 #cs4 #f;d4 nett each4 ,,latest ,,volume #ab4 ,,bishop ,,patteson ,,of ,,the ,,cannibal ,,islands4 ,e4 ,,grierson4 8,the life story of ,bishop ,patteson is of such thrilling interest that boys and girls cannot help being fascinated by it40--,teachers' ,times4 ,illustration3 ,vol4 #c4 ,illustration3 ,vol4 #d4 ,illustration3 ,vol4 #a4 ,illustration3 ,vol4 #b4 ,,earlier ,,volumes #a4 ,a ,,hero ,,of ,,the ,,afghan ,,frontier4 ,the ,life of ,dr4 ,t4 ,l4 ,,pennell1 of ,bannu4 ,a4 ,m4 ,,pennell1 ,m4,b41 ,b4,s47,lond471 ,b4,,sc4 #b4 ,,missionary ,,crusaders4 ,rev4 ,,claud ,,field1 ,m4,a4 #c4 ,,judson1 ,,the ,,hero ,,of ,,burma4 ,,jesse ,,page1 ,f4,r4,g4,s4 #d4 ,,on ,,trail ,,and ,,rapid ,,by ,,dog-,,sled ,,and ,,canoe4 ,bishop ,bompas's ,life amongst ,red ,indians ,esquimo4 ,rev4 ,h4 ,a4 ,,cody1 ,m4,a4 #e4 ,,missionary ,,knights ,,of ,,the ,,cross4 ,rev4 ,j4 ,c4 ,,lambert1 ,m4,a41 ,d4,d4 #f4 ,,missionary ,,heroines ,,of ,,the ,,cross4 ,by ,,canon ,,dawson4 #g4 ,,livingstone1 ,,the ,,hero ,,of ,,africa4 ,by ,r4 ,b4 ,,dawson1 ,m4,a47,oxon74 #h4 ,,by ,,eskimo ,,dog-,,sled ,,kayak4 ,by ,dr4 ,s4 ,k4 ,,hutton1 ,m4,b41 ,c4,m4 #i4 ,,missionary ,,explorers4 ,by ,r4 ,m4 ,a4 ,,ibbotson4 #aj4 ,,arnot1 ,a ,,knight ,,of ,,africa4 ,rev4 ,e4 ,,baker4 #aa4 ,,barbrooke ,,grubb1 ,,pathfinder4 ,n4 ,j4 ,,davidson1 ,b4,a47,oxon7 99 99 99 99 99 ,illustration3 ,binding of the ,russell ,series4 ,,the ,,russell ,,series ,,for ,,boys ,,girls ,a ,series of handsome ,gift ,books for ,boys ,girls4 ,with ,coloured and other ,illustrations4 #cs4 #f;d4 nett each4 ,,latest ,,volume #ab4 ,,stories ,,of ,,early ,,exploration4 ,by ,a4 ,,williams1 ,b4,a47,oxon47 ,,some ,,of ,,the #aa ,,earlier ,,volumes ,,stories ,,of ,,red ,,indian ,,adventure4 ,stirring narratives of bravery and peril4 ,h4 ,w4 ,g4 ,,hyrst4 ,,stories ,,of ,,elizabethan ,,heroes4 ,e4 ,,gilliat1 ,m4,a41 sometime ,master at ,harrow4 ,,stories ,,of ,,polar ,,adventure4 ,h4 ,w4 ,g4 ,,hyrst4 ,,stories ,,of ,,great ,,pioneers4 ,,edgar ,,sanderson1 ,m4,a4 ,,stories ,,of ,,great ,,scientists4 ,c4 ,r4 ,,gibson1 ,f4,r4,s4,e4 99 99 99 99 99 ,,books ,,on ,,popular ,,science ,by ,,charles ,r4 ,,gibson1 ,,ll4,d41 ,f4,r4,s4,e4 8,mr4 ,gibson has fairly made his mark as a populariser of scientific knowledge40--,guardian4 8,mr4 ,gibson has a fine gift of exposition40--,birmingham ,post4 ,,modern ,,electrical ,,conceptions4 ,illustrated4 #abs4 #f;d4 nett4 ,,in ,,the ,,science ,,of ,,to-,,day ,,series4 ,illustrated4 #fs4 nett each4 ,,scientific ,,ideas ,,of ,,to-,,day4 ,a ,popular ,account of the ,nature of ,matter1 ,electricity1 ,light1 ,heat1 c4 c4 ,,electricity ,,of ,,to-,,day4 ,,wireless ,,of ,,to-,,day4 ,by ,,charles ,r4 ,,gibson1 ,f4,r4,s4,e41 ,w4 ,b4 ,,cole4 ,,in ,,the ,,romance ,,library4 ,illustrated4 #fs4 nett each4 ,,the ,,romance ,,of ,,modern ,,electricity4 ,,the ,,romance ,,of ,,modern ,,photography4 ,,the ,,romance ,,of ,,modern ,,manufacture4 ,,the ,,romance ,,of ,,scientific ,,discovery4 ,,the ,,romance ,,of ,,coal4 ,,heroes ,,of ,,the ,,scientific ,,world4 #fs4 nett4 ,,what ,,is ,,electricity8 ,long #hvo4 ,with #h ,illustrations4 #fs4 nett4 99 99 99 99 99 ,,the ,,amusements ,,series ,by ,,charles ,r4 ,,gibson1 ,,ll4,d41 ,f4,r4,s4,e4 ,extra ,crown #hvo4 ,fully illustrated4 #es4 nett each4 ,illustration ,,vol4 ,,iii4 ,,chemical ,,amusements ,,experiments4 ,,new ,,volume4 ,,vol4 ,,ii4 ,,scientific ,,amusements ,,experiments4 ,,vol4 ,i4 ,,electrical ,,amusements ,,experiments4 8,dr4 ,c4 ,r4 ,,gibson',s ,,books ,,on ,,science ,,have ,a ,,world-,,wide ,,reputation4 ,every experiment is so clearly explained and skilfully handled that the lesson is learnt at once without difficulty4 ,he has such an engaging way of imparting his knowledge that he is entertainingly educative4 ,an admirable gift book1 packed with illustrations showing how the experiments can be carried out without much trouble or expense40--,yorkshire ,observer4 99 99 99 99 99 ,,classical ,,stories4 ,by ,prof4 ,a4 ,j4 ,,church 8,the ,headmaster of ,eton 7,dr4 the ,hon4 ,e4 ,lyttelton7 advised his hearers1 in a recent speech at the ,royal ,albert ,institute1 to read ,professor ,a4 ,j4 ,church's #8,stories from ,homer1' some of which1 he said1 he had read to ,eton boys after a hard school day1 and at an age when they were not in the least desirous of learning1 but were anxious to go to tea4 ,the stories were so brilliantly told1 however1 that those young ,etonians were entranced by them1 and they actually begged of him to go on1 being quite prepared to sacrifice their tea-time40 ,profusely illustrated4 ,extra ,crown #hvo4 #es4 nett each4 ,the ,children's neid ,the ,children's ,iliad ,the ,children's ,odyssey ,the ,faery ,queen her ,knights ,the ,crusaders ,greek ,story and ,song ,stories from ,homer ,stories from ,virgil ,the ,crown of ,pine ,stories of the ,east from ,herodotus ,story of the ,persian ,war ,stories from ,livy ,roman ,life in the ,days of ,cicero ,count of ,saxon ,shore ,the ,hammer ,story of the ,iliad ,story of the ,odyssey ,heroes of ,chivalry ,romance ,helmet and ,spear ,stories of ,charlemagne 99 99 99 99 99 ,,the ,,king',s ,,library ,with many ,coloured ,illustrations4 #es4 nett each4 ,,latest ,,volume #g4 ,,cranford4 ,,mrs4 ,,gaskell4 ,,the ,,children',s ,,odyssey4 ,prof4 ,a4 ,j4 ,,church ,,the ,,children',s ,,iliad4 ,prof4 ,a4 ,j4 ,,church ,a ,,knight ,,errant4 ,n4 ,j4 ,,davidson1 ,b4,a4 ,,the ,,children',s ,,aeneid4 ,prof4 ,a4 ,j4 ,,church ,,vicar ,,of ,,wakefield4 ,,goldsmith ,,the ,,faery ,,queen4 ,prof4 ,a4 ,j4 ,,church 99 99 99 99 99 ,,the ,,marvel ,,library ,fully ,illustrated4 ,each ,volume1 #ds4 nett4 ,,latest ,,volume #aj4 ,,marvels ,,of ,,animal ,,ingenuity4 ,by ,c4 ,a4 ,,ealand1 ,m4,a4 ,,marvels ,,of #a4 ,,scientific ,,invention4 ,by ,t4 ,w4 ,,corbin4 #b4 ,,aviation4 ,maj4 ,c4 ,c4 ,,turner1 ,r4,a4,f4 #c4 ,,geology4 ,by ,e4 ,s4 ,,grew1 ,m4,a4 #d4 ,,war ,,inventions4 ,by ,t4 ,w4 ,,corbin4 #e4 ,,photography4 ,c4 ,r4 ,,gibson4 #f4 ,,the ,,ship4 ,by ,lieut-,com4 ,e4 ,,keble ,,chatterton1 ,r4,n4,v4,r4 #g4 ,,mechanical ,,invention4 ,by ,t4 ,w4 ,,corbin4 #h4 ,,world',s ,,fisheries4 ,by ,,sidney ,,wright4 #i4 ,,railways4 ,by ,a4 ,,williams4 ,illustration3 ,specimen ,binding4 99 99 99 99 99 ,,two ,,excellent ,,reciters ,each volume consists of over #gjj pages1 cloth1 #fs4 nett each4 ,also ,thin ,paper ,edition 7measuring #f-c_/d #c_/d ins41 and only #c_/d of an inch thick71 price #gs4 #f;d4 nett each4 ,they also contain practical ,introductions by ,prof4 ,cairns ,james1 ,professor of ,elocution at the ,royal ,college of ,music4 ,,the ,,golden ,,reciter ,selected from the works of ,rudyard ,kipling1 ,r4 ,l4 ,stevenson1 ,conan ,doyle1 ,thomas ,hardy1 ,austin ,dobson1 ,christina ,rossetti1 ,maurice ,hewlett1 ,a4 ,w4 ,pinero1 ,sydney ,grundy1 c41 c4 8,an admirable collection of pieces both in prose and verse40--,spectator4 8,offers an unusual wealth from authors of to-day40--,the ,athenum4 8,far superior to anything we have yet seen40--,western ,press4 ,,the ,,golden ,,humorous ,,reciter ,from ,anstey1 ,barrie1 ,major ,drury1 ,j4 ,k4 ,jerome1 ,barry ,pain1 ,a4 ,w4 ,pinero1 ,owen ,seaman1 ,g4 ,bernard ,shaw1 c41 c4 8,a most comprehensive well-chosen collection of some hundreds of pieces4 ,a small encyclopdia of ,english humour40--,the ,spectator4 8,unquestionably the best collection of modern humorous pieces for recitation which has yet been issued40--,the ,dundee ,advertiser4 ,,the ,,pilgrim',s ,,way ,by ,prof4 ,,sir ,a4 ,t4 ,,quiller-,,couch ,a ,little ,book for ,wayfaring ,men4 ,in ,prose and ,verse4 ,fcap4 #hvo1 cloth1 #cs4 #f;d4 nett2 thin paper1 #es4 nett2 buff leather yapp1 in a box1 #fs4 nett4 8,the very flower of a cultivated man's reading40--,country ,life4 99 99 99 99 99 ,,microscopes ,,accessories ,,microscopical ,,preparations4 ,large ,stock of ,slides in ,botany1 ,zoology1 ,petrology1 ,diatoms1 and ,commercial ,fibres4 ,,photomicrographic ,,and ,,other ,,scientific ,,lantern ,,slides4 ,see ,illustrations in this book4 ,thousands in ,stock4 ,illustration3 ,,mersol ,the ,improved ,immersion ,oil1 ,stains1 ,mounting ,media and ,reagents4 ,,pond ,,life and other ,collecting ,apparatus4 ,,aplanatic ,,magnifiers4 ,,flatters ,,garnett ,,ltd41 #cji ,,oxford ,,road 7,opposite the ,university71 ,,manchester4 99 99 99 99 99 ,,the ,,romance ,,of ,,aeronautics ,,an ,,interesting ,,account ,,of ,,the ,,growth ,,and ,,achievements ,,of ,,all ,,kinds ,,of ,,aerial ,,craft ,,by ,,charles ,c4 ,,turner ,holder of the ,royal ,aero ,society's ,aviation ,certificate1 ,author of 8,aerial ,navigation of ,to-day10 c4 c4 ,with ,fifty-two ,illustrations and ,diagrams4 ,extra ,crown #hvo4 #es4 8,a capital survey by an expert writer40--,guardian4 8,brightly written1 exceptionally well illustrated1 and shows a due regard for historical accuracy40--,aeronautics4 8,a most interesting book40--,spectator4 8,a most complete history 444 told with lucidity and enthusiasm1 and brimful of interest40--,truth4 8,set forth with a persuasive and accomplished pen40--,pall ,mall ,gazette4 ,,the ,,romance ,,of ,,animal ,,arts ,,crafts ,,describing ,,the ,,wonderful ,,intelligence ,,of ,,animals ,,revealed ,,in ,,their ,,work ,,as ,,masons1 ,,paper ,,makers1 ,,raft ,,diving-,,bell ,,builders1 ,,miners1 ,,tailors1 ,,engineers ,,of ,,roads ,,bridges1 c4 c4 ,,by ,h4 ,,coupin1 ,d4,,sc4 ,,john ,,lea1 ,b4,a4 7,,cantab47 ,with ,thirty ,illustrations4 ,extra ,crown #hvo4 #es4 8,will carry most readers1 young and old1 from one surprise to another40--,glasgow ,herald4 8,a charming subject1 well set forth1 and dramatically illustrated40--,athenum4 8,it seems like pure romance to read of the curious ways of ,nature's craftsmen1 but it is quite a true tale that is set forth in this plentifully illustrated book40--,evening ,citizen4 8,this popular volume of ,natural ,history is written by competent authorities1 and besides being entertaining is instructive and educative40--,liverpool ,courier4 ,,the ,,romance ,,of ,,missionary ,,heroism ,,true ,,stories ,,of ,,the ,,intrepid ,,bravery ,,and ,,stirring ,,adventures ,,of ,,missionaries ,,with ,,uncivilized ,,men1 ,,wild ,,beasts1 ,,and ,,the ,,forces ,,of ,,nature ,,in ,,all ,,parts ,,of ,,the ,,world ,,by ,,john ,c4 ,,lambert1 ,m4,a41 ,d4,d4 ,with ,thirty-six ,illustrations4 ,extra ,crown #hvo4 #es4 8,a book of quite remarkable and sustained interest40--,sheffield ,telegraph4 8,the romantic aspect of missionary careers is treated without undue emphasis on the high prevailing motive4 ,but its existence is the fact which unifies the eventful history40--,athenum4 8,we congratulate ,dr4 ,lambert and his publishers4 ,dr4 ,lambert has proved that the missionary is the hero of our day1 and has written the most entrancing volume of the whole romantic series40--,expository ,times4 ,,the ,,romance ,,of ,,early ,,british ,,life ,,from ,,the ,,earliest ,,times ,,to ,,the ,,coming ,,of ,,the ,,danes ,,by ,,professor ,g4 ,f4 ,,scott ,,elliot ,m4,a4 7,cantab471 ,b4,sc4 7,edin471 ,f4,r4,g4,s41 ,f4,l4,s4 ,author of 8,the ,romance of ,savage ,life10 8,the ,romance of ,plant ,life10 c4 c4 ,with over ,thirty ,illustrations4 ,extra ,crown #hvo4 #es4 8,calculated to fascinate the reader40--,field4 8,every chapter is full of information given in fascinating form4 ,the language is simple1 the style is excellent1 and the information abundant40--,dundee ,courier4 99 99 99 99 99 ,,the ,,ian ,,hardy ,,series ,,by ,,commander ,e4 ,,hamilton ,,currey1 ,r4,n4 ,each ,volume with ,illustrations in ,colour4 #es4 each ,,ian ,,hardy',s career in ,h4,m4 ,navy is told in four volumes1 which are described below4 ,each volume is complete in itself1 and no knowledge of the previous volumes is necessary1 but few boys will read one of the series without wishing to peruse the others4 ,,ian ,,hardy1 ,,naval ,,cadet 8,a sound and wholesome story giving a lively picture of a naval cadet's life40--,birmingham ,gazette4 8,a very wholesome book for boys1 and the lurking danger of ,ian's ill deeds being imitated may be regarded as negligible in comparison with the good likely to be done by the example of his manly1 honest nature4 ,ian was a boy whom his father might occasionally have reason to whip1 but never feel ashamed of40--,united ,service ,magazine4 ,,ian ,,hardy1 ,,midshipman 8,a jolly sequel to his last year's book40--,christian ,world4 8,the #8real thing4'444 ,certain to enthral boys of almost any age who love stories of ,british pluck40--,observer4 8,commander ,e4 ,hamilton ,currey1 ,r4,n41 is becoming a serious rival to ,kingston as a writer of sea stories4 ,just as a former generation revelled in ,kingston's doings of his three heroes from their middy days until they became admirals all1 so will the present-day boys read with interest the story of ,ian ,hardy4 ,last year we knew him as a cadet2 this year we get ,ian ,hardy1 ,midshipman4 ,the present instalment of his stirring history is breezily written40--,yorkshire ,observer4 ,,ian ,,hardy1 ,,senior ,,midshipman 8,of those who are now writing stories of the sea1 ,commander ,currey holds perhaps the leading position4 ,he has a gift of narrative1 a keen sense of humour1 and above all he writes from a full stock of knowledge40--,saturday ,review4 8,it is no exaggeration to say that ,commander ,currey bears worthily the mantle of ,kingston and ,captain ,marryat40--,manchester ,courier4 8,the ,ian ,hardy ,series is just splendid for boys to read1 and the best of it is that each book is complete in itself4 ,but not many boys will read one of the series without being keenly desirous of reading all the others40--,sheffield ,telegraph4 ,,ian ,,hardy ,,fighting ,,the ,,moors 8,by writing this series the author is doing national service1 for he writes of the ,navy and the sea with knowledge and sound sense4444 ,what a welcome addition the whole series would make to a boy's library40--,daily ,graphic4 8,the right romantic stuff1 full of fighting and hairbreadth escapes4444 ,commander ,currey has the secret of making the men and ships seem actual40--,times4 8,by this time ,ian ,hardy has become a real friend and we consider him all a hero should be40--,outlook4 99 99 99 99 99 ,a ,,hero ,,of ,,the ,,afghan ,,frontier ,,the ,,splendid ,,life ,,story ,,of ,t4 ,l4 ,,pennell1 ,m4,d41 ,b4,sc41 ,f4,r4,c4,s4 ,,retold ,,for ,,boys ,,girls ,,by ,,alice ,m4 ,,pennell1 ,m4,b41 ,b4,s4 7,lond471 ,b4,sc4 ,with many ,illustrations a ,frontispiece in ,colour4 ,extra ,crown #hvo4 #bs4 #f;d4 8,this is the glorious life story of ,dr ,t4 ,l4 ,pennell retold for boys and girls40--,church ,family ,newspaper4 8,the life story of a fearless ,englishman of the best kind40--,daily ,telegraph4 8,one of the very finest men who ever devoted his life to the ,missionary cause40--,guardian4 8,a great story of a grand ,christian hero40--,christian ,world4 ,,missionary ,,knights ,,of ,,the ,,cross ,,true ,,stories ,,of ,,the ,,splendid ,,courage ,,patient ,,endurance ,,of ,,missionaries ,,in ,,their ,,encounters ,,with ,,uncivilized ,,man1 ,,wild ,,beasts ,,the ,,forces ,,of ,,nature ,,in ,,all ,,parts ,,of ,,the ,,world ,,by ,,canon ,e4 ,c4 ,,dawson1 ,m4,a4 7,oxon47 ,with ,thirty-six ,illustrations a ,frontispiece in ,colour4 ,extra ,crown #hvo4 #bs4 #f;d4 8,after all there are few men who see so much of adventure as the missionaries who go fother among the uncivilised4 ,no better book could be put into the hands of a lad than this present record of derring-do4444 ,a volume of thrilling adventure40--,eastern ,morning ,news4 8,a most entrancing book40--,aberdeen ,daily ,journal4 8,most readable4 ,written with rare skill and attractively illustrated40--,expository ,times4 ,,on ,,trail ,,rapid ,,by ,,dog-,,sled ,,canoe ,,the ,,story ,,of ,,bishop ,,bompas',s ,,life ,,amongst ,,the ,,red ,,indians ,,eskimo4 ,,retold ,,for ,,boys ,,girls ,,by ,,the ,,rev4 ,h4 ,a4 ,,cody1 ,m4,a4 ,with ,twenty-six ,illustrations a ,frontispiece in ,colours4 ,extra ,crown #hvo4 #bs4 #f;d4 8,a book of golden deeds1 full of inspiration40--,queen4 8,an admirable picture of a great career40--,spectator4 8,an admirable book for the young1 full of interest and of healthy romance40--,irish ,times4 8,should prove an inspiration and a help to all young people40--,record4 ,a ,,charming ,,anthology ,,by 8,q0 ,,the ,,pilgrims' ,,way ,a ,,little ,,scrip ,,of ,,good ,,counsel ,,for ,,travellers ,,by ,,sir ,a4 ,t4 ,,quiller-,,couch ,professor of ,english ,literature at ,cambridge ,university ,cloth1 price1 nett1 #es4 ,thin paper edition in leather1 #fs4 nett2 buffed leather1 yapp1 in a box1 price1 nett1 #fs4 8,prof4 ,quiller-,couch is the prince of anthologists40--,the ,glasgow ,evening ,news4 8,a little book of grave and beautiful thoughts4 ,it would be difficult to better the selections40--,the ,guardian4 8,the poems and prose passages are chosen--as might be safely foretold--with taste and discrimination1 and the volume will be found a heartening companion40--,the ,tribune4 8,the very flower of a cultivated man's reading40--,country ,life4 8,prof4 ,quiller-,couch's anthologies are the best of their kind in modern ,english literature40--,the ,morning ,post4 ,,the ,,golden ,,reciter ,,recitations ,,and ,,readings ,,in ,,prose ,,and ,,verse ,,selected ,,from ,,the ,,writings ,,of ,,rudyard ,,kipling1 ,r4 ,l4 ,,stevenson1 ,,conan ,,doyle1 ,,thomas ,,hardy1 ,,austin ,,dobson1 ,,christina ,,rossetti1 ,,maurice ,,hewlett1 ,a4 ,w4 ,,pinero1 ,,sydney ,,grundy1 c4 ,,with ,a ,,practical ,,introduction ,,by ,,prof4 ,,cairns ,,james ,professor of ,elocution at the ,royal ,college of ,music and the ,guildhall ,school of ,music ,extra crown #hvo1 over #gjj pages1 cloth1 nett1 #fs42 also a thin paper pocket edition1 with coloured edges1 nett1 #fs4 #f;d4 8,an admirable collection of pieces1 both in prose and verse40--,spectator4 8,far superior to anything we have yet seen40--,western ,press4 8,a more admirable book of its kind could not well be desired40--,liverpool ,courier4 ,,the ,,golden ,,humorous ,,reciter ,,recitations ,,and ,,readings ,,in ,,prose ,,and ,,verse ,,selected ,,from ,,the ,,writings ,,of ,f4 ,,anstey1 ,j4 ,m4 ,,barrie1 ,,major ,,drury1 ,,jerome ,k4 ,,jerome1 ,,barry ,,pain1 ,a4 ,w4 ,,pinero1 ,,owen ,,seaman1 ,g4 ,b4 ,,shaw1 c4 c4 ,,with ,a ,,practical ,,introduction ,,by ,,prof4 ,,cairns ,,james ,extra crown #hvo1 over #gjj pages1 cloth1 nett1 #fs42 also a thin paper pocket edition1 with coloured edges1 nett1 #fs4 #f;d4 8,unquestionably the best collection of modern humorous pieces for recitations which has yet been issued40--,the ,dundee ,advertiser4 8,packed with things that are fresh and unhackneyed40--,bookman4 8,an excellent selection1 three-fifths of them being taken from the work of the best modern writers40--,the ,world4 8,a most comprehensive and well-chosen collection of some hundreds of pieces--a most catholic array of all that is good in ,english literature1 and a small encyclopdia of ,english humour40--,the ,spectator4 99 99 99 99 99 ,,the ,,new ,,art ,,library 8,the admirable ,new ,art ,library40--,connoisseur4 ,new ,volume4 ,just ,ready4 ,,water ,,colour ,,painting ,,alfred ,w4 ,,rich4 ,with over ,sixty ,illustrations4 ,price #ajs4 #f;d4 nett4 8,no artist living is better qualified to undertake a text-book on water colour painting than ,mr ,rich4 ,not only is he one of the most distinguished exponents of the art in this country1 but he has had considerable experience and success as a teacher4 ,this admirable volume 4440--,studio4 8,a book on the art of water colour painting by one of its best living practitioners4444 ,mr ,rich's technique1 clean1 direct1 and scrupulous1 is the best possible foundation for the student40--,times4 ,,the ,,practice ,,of ,,oil ,,painting ,,solomon ,j4 ,,solomon1 ,r4,a4 ,with ,eighty ,illustrations4 ,price #ajs4 #f;d4 nett4 8,eminently practical4444 ,can be warmly recommended to all students40--,daily ,mail4 8,the work of an accomplished painter and experienced teacher40--,scotsman4 8,if students were to follow his instructions and1 still more1 to heed his warnings1 their painting would soon show a great increase in efficiency40--,manchester ,guardian4 ,,human ,,anatomy ,,for ,,art ,,students ,sir ,,alfred ,d4 ,,fripp1 ,k4,c4,v4,o41 ,c4,b41 ,lecturer upon ,anatomy at ,guy's and ,,ralph ,,thompson4 ,drawings by ,,innes ,,fripp1 ,a4,r4,c4,a41 ,master of ,life ,class1 ,city ,guilds ,art ,school4 #aea ,illustrations4 #aes4 nett4 8,the character of this book all through is clearness1 both in the letterpress and the illustrations4 ,the latter are admirable40--,spectator4 8,just such a work as the art student needs1 and is probably all that he will need4 ,it is very fully illustrated4 ,there are #i plates showing different views of the skeleton and the muscular system1 #bc reproductions of photographs from life1 and over #acj figures and drawings40--,glasgow ,herald4 ,,modelling ,,sculpture ,,albert ,,toft1 ,hon4 ,associate of the ,royal ,college of ,art1 ,member of the ,society of ,british ,sculptors4 ,with #aah ,illustrations4 #aes4 nett4 8,mr ,toft's reputation as a sculptor of marked power and versatility guarantees that the instruction he gives is thoroughly reliable40--,connoisseur4 8,will be exceeding useful and indispensable to all who wish to learn the art of sculpture in its many branches4 ,the book will also appeal to those who have no intention of learning the art1 but wish to know something about it4 ,mr ,toft writes very clearly40--,field4 ,,the ,,practice ,,science ,,of ,,drawing ,,harold ,,speed1 ,member of the ,royal ,society of ,portrait ,painters4 ,with #ic ,illustrations1 #ajs4 #f;d4 nett4 8,this book is of such importance that everyone interested ,in the subject must read it40--,,walter ,,sickert in ,the ,daily ,news4 8,altogether this is one of the best volumes in the admirable series to which it belongs40--,literary ,world4 8,there are many new and original ideas in the book40--,the ,outlook4 ,,the ,,artistic ,,anatomy ,,of ,,trees ,,rex ,,vicat ,,cole4 ,with #ejj ,illustrations ,diagrams4 #aes4 nett4 8,no work on art published during recent years is better calculated to be of practical assistance to the student40--,connoisseur4 8,excellently and copiously illustrated40--,times4 8,like all volumes of the ,new ,art ,library1 thorough in its teaching1 eminently practical in its manner of presenting it1 and so splendidly illustrated that not a rule is laid down or a piece of advice given but what a drawing accompanies it4 ,mr ,vicat ,cole's ability as a landscape painter is well known1 and he unites to his executive talents the qualifications of an accomplished teacher40--,connoisseur4 ,,seeley1 ,,service ,,co41 ,,limited 99 99 99 99 99 ,transcriber's ,notes3 ,the one footnote has been moved to the end of its chapter4 ,illustrations have been moved to paragraph breaks near where they are mentioned4 ,punctuation has been made consistent4 ,variations in spelling and hyphenation were retained as they appear in the original publication1 except that obvious typos have been corrected4 p4 #ej3 ,page reference is missing 7described on p4 47