,illustration3 ,plate ,i4 ,london1 ,john ,van ,voorst4 ,,an ,,elementary ,,text-,,book ,,of ,,the ,,microscope2 ,,including ,a ,,description ,,of ,,the ,,methods ,,of ,,preparing ,,and ,,mounting ,,objects1 ,,etc4 ,,by ,j4 ,w4 ,,griffith1 ,m4,d41 ,f4,l4,s41 ,,etc41 ,,member ,,of ,,the ,,royal ,,college ,,of ,,physicians2 ,,conjoint ,,author ,,of ,,the ,,micrographic ,,dictionary1 ,,etc4 ,,with ,,twelve ,,coloured ,,plates1 ,,containing #dea ,,figures4 ,illustration ,,london3 ,,john ,,van ,,voorst1 ,,paternoster ,,row4 ,,mdccclxiv4 ,the right of translation is reserved4 ,,preface4 ,the object of this little work is to furnish an elementary course of instruction in the use of the ,microscope1 and on its application to the examination of the structure of plants and animals4 ,assuming that the reader has had no previous acquaintance with the ,microscope1 or with the study of natural history1 ,i have attempted to render the descriptions of the objects as simple as possible4 ,at the same time1 the technical terms have been added and explained1 in order gradually to render them familiar to the reader1 and thus facilitate the future study of larger and more detailed works4 ,the objects figured and described comprise the principal structures and more minute forms of both the vegetable and the animal kingdom1 those having been selected which are common and readily procurable4 ,a chapter has been given upon the optical principles on which the action of the instrument depends 7which will assist the reader to understand the operation of its constituent parts71 including a sketch of the subject of polarized light4 ,the order in which the subjects are treated is scientific1 and particular directions have been given for the examination of the objects4 ,the small size of the work has necessitated the exclusion of figurative descriptions1 so that it is adapted rather for a worker than a reader2 at the same time1 the matter forms a course1 and must be taken as a whole for the proper comprehension of the subjects4 ,the technical terms used are referred to in the ,index1 so as to furnish to some extent a glossary of terms2 and their derivation is given1 to facilitate their recollection4 ,the figures1 with very few exceptions1 are drawn from nature1 and are coloured that the objects may be more easily recognized4 ,the magnifying powers under which they have been drawn are denoted by a small number placed beneath each figure3 and the particular attention of the reader is requested to this point2 otherwise the whole subject will be utterly confused2 so much does the appearance of objects vary under different powers4 ,directions are given for preparing and mounting objects1 implying that the reader will collect specimens for himself1 which is to be strongly recommended as the best method of acquiring a practical and useful acquaintance with the objects4 ,these will serve to furnish permanent landmarks in the great ocean of structural forms1 will probably recall in after-years pleasant recollections of early excursions in search of the beauties of nature1 and1 surely1 deepen the conviction of the existence of their ,all-wise ,creator4 ,j4 ,w4 ,g4 ,,contents4 ,,chap4 ,,page ,i4 ,,the ,,microscope #a ,,ii4 ,,the ,,mounting ,,of ,,objects #aj ,,iii4 ,,vegetable ,,elements ,,and ,,tissues #ai ,,iv4 ,,vegetable ,,organs #ca ,v4 ,,ferns #di ,,vi4 ,,mosses #ed ,,vii4 ,,alg #fd ,,viii4 ,,lichens #ia ,,ix4 ,,fungi #if ,x4 ,,animal ,,elements ,,and ,,tissues #aac ,,xi4 ,,articulata #abg ,,xii4 ,,radiata #aec ,,xiii4 ,,protozoa #aee ,,xiv4 ,,optical ,,principles #afg ,,plate ,i4 ,,frontispiece4 ,,vegetable ,,tissues1 c4 ,fig4 #a4 ,leaf of ,geranium3 cells1 chlorophyll1 and intercellular passages4 #b4 ,cells of ,apple4 #c4 ,starch-granules3 a1 of ,wheat2 b1 of ,arrowroot2 c1 of ,potato2 d1 of ,oat2 e1 of ,lentil2 f1 of ,rice4 #d4 ,cells of ,potato1 containing ,starch4 #e4 ,garden ,rhubarb-stalk3 a1 raphides2 b1 reticulated duct2 c1 spiral vessel2 d1 woody fibre2 e1 annular vessel4 #f4 ,wood-cells from stem of ,chrysanthemum4 #g4 ,deal1 transverse section3 a1 glandular tissue2 b1 woody fibre4 #h4 ,deal1 longitudinal 7radial7 section of glandular tissue4 #i4 ,deal1 longitudinal section of woody fibre4 #aj4 ,deal1 tangential section4 #aa4 ,holly1 wood of3 a1 porous cells2 b1 d1 e1 wood-cells2 c1 dotted ducts4 #ab4 ,hairs1 vegetable3 a1 b1 of ,groundsel2 c1 of ,london ,pride2 d1 e1 of ,geranium2 f1 of ,chrysanthemum4 #ac4 ,epidermis of ,geranium-leaf4 #ad4 ,style of ,crocus1 with pollen-granule and-tube4 #ae4 ,pollen-grain of ,crocus1 with pollen-tube4 #af4 ,pollen of ,primrose4 #ag4 ,pollen of ,sunflower4 #ah4 ,pollen of ,convolvulus major4 #ai4 ,caraway-seed4 #bj4 ,needle-point4 #ba4 ,sting of ,nettle4 #bb4 ,hair of ,spiderwort4 #bc4 ,hair of ,spiderwort1 single cell4 #bd4 ,epidermis of ,geranium-petal4 #be4 ,petal of ,chickweed4 #bf4 ,sepal of ,chickweed4 #bg4 ,seed of ,poppy4 #bh4 ,epidermis of ,deutzia4 #bi4 ,seed of ,mignonette4 #cj4 ,pollen of ,chickweed1 dry4 #ca4 ,pollen of ,chickweed1 in water4 #cb4 ,flower of ,chickweed4 #cc4 ,epidermis of petal of ,chickweed4 #cd4 ,hairs of calyx of ,chickweed4 #ce4 ,hairs of seed of ,collomia4 #cf4 ,stem of ,dicotyledon1 section of4 #cg4 ,stem of ,monocotyledon1 section of4 #ch4 ,seed of ,shepherd's ,purse1 transverse section4 #ci4 ,stamen of ,chickweed4 #dj4 ,stigma of ,chickweed4 #da4 ,ovary of ,chickweed4 #db4 ,leaf of ,chickweed4 #dc4 ,seed of ,wallflower1 section of4 #dd4 ,seed of ,wallflower1 radicle and cotyledons4 #de4 ,embryo-sac of ,chickweed4 #df4 ,embryo-sac of ,chickweed4 #dg4 ,embryo-sac of ,chickweed4 #dh4 ,wheat1 cotyledon and leaves of1 section4 #di4 ,mustard-seed1 cotyledons and radicle4 #ej4 ,mustard-seed1 transverse section4 #ea4 ,chickweed1 seed of4 #eb4 ,seed of ,eccremocarpus scaber4 #ec4 ,grain of ,wheat3 a1 cotyledon2 b1 embryo2 c1 radicle2 d1 albumen4 #ed4 ,ovule of ,wallflower4 #ee4 ,cotyledons of ,chickweed4 #ef4 ,plum-stone1 section of4 ,a ,,text-,,book ,,of ,,the ,,microscope4 ,,chapter ,i4 ,,the ,,microscope4 ,the microscope 7from 1 little1 and 1 to see71 so called because it enables us to see objects which are too small to be seen with the naked eye1 consists of several parts1 each of which has its special use4 ,as the proper management of these is of great importance in the successful application of the instrument to minute investigations1 we shall commence with the consideration of their names and uses1 including those of the more important pieces of accessory apparatus4 ,microscope4--,the foot of the microscope is that part which supports the instrument upon the table2 it is connected above with the stand1 of which it is often considered a part4 ,the stand sometimes consists of a single rod or pillar2 but in the best microscopes it is composed of two upright plates1 between which1 at the upper part1 the rest of the microscope swings stiffly upon an axle4 ,arising from this axle1 indirectly through the medium of parts which require no special mention1 is an arm1 to which the body is fixed4 ,the body is moveable up and down by one or two large milled heads1 connected with a grooved rod or pinion1 which works in the teeth of a rack fixed to the back of the body1 or of the arm which supports the body4 ,the large milled heads form the 8coarse movement10 as it is called4 ,on the top of the arm1 or on the front and lower part of the body of the microscope1 is placed the 8fine movement10 consisting of a small milled head1 with a fine screw1 for moving the body through very small distances4 ,next is the 8stage10 or flat plate1 upon which the objects to be viewed are placed4 ,this is often so arranged that1 by turning two milled heads1 the object can be moved backwards and forwards1 or from side to side2 it is then a 8moveable stage40 ,the eye-piece slides into the upper end of the body2 and the object-glass screws into its lower end4 ,beneath the stage is the mirror1 which reflects the light through the object1 the object-glass1 and eye-piece to the eye4 ,object-glasses4--,the object-glasses are the most valuable parts of the instrument4 ,there are generally three or more of them2 and1 by means of an 8adapter10 any object-glass can be made to fit any microscope4 ,great care is required in their use1 especially to avoid scratching the lower surface of the glass1 which is sometimes accidentally done by pressing the surface against any hard body1 or allowing such a body to fall upon it4 ,when not in use1 the object-glasses should either be put away in the brass boxes or covered with a small bell-glass1 to prevent their receiving any injury4 ,the object-glasses possess various magnifying powers1 according to the distance at which they require to be placed from the object for distinct vision3 this is not1 however1 absolutely correct1 yet may serve as a general expression4 ,thus we have a #a-;inch1 -inch1 -inch object-glass1 c4 ,the object-glasses1 for brevity1 are often called powers4 ,as a beginner may at first have some difficulty in distinguishing a high from a low power1 it may be remarked that the size of the lower glass is larger the lower the power3 but1 in the case of the better object-glasses1 the focal distance is engraved on the box in which the object-glass is packed when put away4 ,as the coarse movement raises or depresses the body and object-glass through comparatively large distances1 it must be used only with the lower object-glasses1 i4 e4 those of low or little magnifying power1 as the #b-;inch1 #a-;inch1 or -inch1 or to bring the object-glass near the focal distance with the higher powers2 whereas the fine movement serves to adjust the higher powers1 as the -inch1 c4 ,if the object-glasses should become soiled on the lower face1 this should be wiped very gently with an old silk handkerchief or piece of very soft wash-leather1 previously shaken to displace dust4 ,the same method will answer to cleanse the upper surface of the eye-piece4 ,great care must be taken that a slide which has been warmed in any experiment be not placed near the object-glass until quite cold4 ,mirror4--,the mirror has sometimes one silvered face only1 at others two--one flat1 the other concave4 ,the flat surface is used to reflect the light upon the object when the light is too great with the concave surface4 ,beneath the stage1 in most microscopes1 is a circular moveable 8diaphragm10 perforated with holes of various sizes1 to allow more or less of the light reflected by the mirror to pass through1 as may be required4 ,when opake objects are viewed1 the mirror should be turned aside1 so as not to reflect any light through the stage4 ,eye-pieces4--,with all microscopes1 two or more eye-pieces are supplied4 ,these possess different magnifying powers1 and are lettered or numbered accordingly2 the lowest power with the earliest letters of the alphabet1 or with the smallest numbers1 thus3 ,a1 ,b1 ,c2 or #a1 #b1 #c1 c4 ,forceps4--,these are fine pincers1 for holding minute bodies to be viewed as opake objects4 ,in use1 they are inserted by a stem connected with a joint1 in an aperture1 generally in the stage2 and are moveable in all directions4 ,live-box4--,this is a brass slide1 perforated in the middle1 to the aperture in which is soldered a short piece of brass tube1 closed at the top with a circular plate of thin glass4 ,a rather wider and longer piece of brass tube slides over the former2 this is also closed at the top by a thin glass plate1 so as to allow of an object being confined or compressed between the two glass plates4 ,it is used for examining living objects in water4 ,knife1 c4--,for cutting slices or sections of objects1 a very sharp knife with a thin back will be found useful2 or a razor may be used for the same purpose4 ,and for picking minute objects to pieces1 or dissection1 fine needles1 cut off short with pliers1 the blunt ends being thrust into hair-pencil sticks1 will be requisite4 ,a pair of fine surgical forceps will also be required1 for taking up minute objects4 ,these should be without teeth1 and the spring-action so weak that the points can be very easily approximated4 ,dipping-tubes4--,for removing minute objects from water1 two or three narrow glass tubes1 of different lengths1 are very useful4 ,these are called 8dipping tubes10 and are used thus3--the tube being held upright between the second finger and the thumb1 the fore finger is placed at the top of the tube to close it2 the tube is then put into the water until the lower end is close to the object1 when1 on suddenly removing the fore finger1 the water will rise in the tube1 carrying the object with it4 ,the fore finger is then again applied to the tube1 and1 as thus held1 the water will not run out4 ,the tube is then held over a watch-glass1 or a slide1 upon which the water and object will fall on removing the fore finger4 ,a small glass spirit-lamp will be found very useful4 ,the spirit for burning should be methylated alcohol1 or wood-naphtha4 ,as these spirits are inflammable1 great care should be taken to keep the stock-bottle away from a candle or other flame1 when filling the lamp4 ,achromatic condenser4--,a very important piece of apparatus1 when high powers are used1 is the achromatic condenser2 it is not1 however1 usually supplied with the cheaper microscopes4 ,it consists of a brass fitting1 placed beneath the stage1 into which an object-glass is screwed1 in an inverted position1 i4 e4 the small end of the object-glass being placed uppermost4 ,it serves to condense the light to a focus upon the object1 so as to illuminate it more brightly2 and as it can be elevated or depressed by a milled head and rack-work1 the object can be viewed by either converging or diverging rays4 ,simple microscope4--,for examining the larger kinds of objects1 and for dissection1 a simple microscope is very useful4 ,this consists of a stand1 a stage1 and an arm supporting a simple lens or combination of lenses1 but without the body of the compound microscope 7as the ordinary microscope is distinctively called74 ,for most purposes1 common plano-convex or doubly convex lenses are sufficient to form the object-glasses of a simple microscope4 ,with the best microscopes1 an 8erector10 or tube containing a pair of lenses1 fitted within the body1 renders the compound microscope capable of answering most of the purposes of a simple microscope4 ,polariscope4--,an expensive but interesting and useful addition to a microscope is a polarizing apparatus1 or polariscope4 ,this consists of a ,nicol's prism1 or a plate of tourmaline1 placed beneath the stage1 and another in the body of the microscope or above the eye-piece2 both in brass fittings4 ,the former is called the polarizer1 and the latter the analyzer4 ,rotating disk4--,another most useful piece of apparatus1 for moving opake objects whilst under the microscope1 in all directions1 is ,smith and ,beck's 8rotating disk40 ,slides4--,the slides upon which objects1 especially those to be viewed as transparent objects1 are to be placed1 should be made of crown or plate glass4 ,they are usually #c inches long1 and #a inch wide2 but ,i prefer them #b inches long1 and #a inch wide1 simply because they take up less room in a cabinet1 and because they do not project beyond the stage on either side4 ,they should not be more than #a_/bjth of an inch thick1 and as colourless and clear as possible4 ,the edges should be ground or filed1 to prevent their scratching the stage4 ,covers4--,the covers are square pieces of very thin glass1 less in breadth than the slides1 so as not to reach their margins2 and of various thicknesses1 the thicker and stronger being used to cover large objects for examination under the lower powers1 and the thinner serving to cover very delicate objects requiring the higher powers4 ,side condenser4--,for illuminating opake objects1 a large plano-convex or doubly convex 8bull's-eye0 lens1 or side condenser1 is used2 this is fixed to an arm1 which slides on a stand1 so as to be capable of being raised or lowered to a suitable height4 ,this is placed between the source of light and the stage1 and at such a distance from the latter that the light may be brought to a focus upon the object4 ,sometimes a 8,lieberkuhn0 or concave silver reflector is used for this purpose4 ,these are the most important pieces of apparatus required in examining microscopic bodies4 ,but the beginner will do well1 if he have the achromatic condenser and the polarizing apparatus1 to lay these aside until he has had considerable practice in examining objects simply with the mirror and the lower powers4 ,general method of observation4--,in the ordinary use of the microscope1 the object to be examined is laid upon the middle of a slide1 which is placed upon the stage4 ,the object is then brought under the centre of the object-glass1 the mirror inclined half towards the light and half towards the object1 until the object is seen to be illuminated1 when1 upon looking through the eye-piece and adjusting the coarse and fine movements1 the object as it comes into focus will be seen1 as it were1 drawn upon a white disk1 which is called the 8field40 ,when the object is wet1 it cannot be viewed without the application of a cover1 because the water evaporates and condenses upon the under surface of the object-glass4 ,to avoid the danger of injuring the object-glass1 or crushing the object by lowering the body and object-glass too much in adjustment to focus1 the best plan is to lower the body by means of the coarse movement until the object-glass appears near the object to the eye placed on one side of the stage1 and then to apply the eye to the eye-piece1 and turn the milled head so as to raise the body and object-glass until the object is brought into focus4 ,in the examination of an object1 it is best to begin with a low power1 so as to obtain a view of the general arrangement of its parts1 and then to apply the higher eye-pieces and powers1 so that the more minute structural details may be observed4 ,illumination4--,the illumination or proper management of the light in using the microscope is of very great importance4 ,the best light1 especially with the low powers1 is daylight1 particularly that reflected from white clouds2 this is least injurious to the eyes4 ,but as daylight cannot always be used for microscopic investigations1 and as cloud-light is insufficient with the higher powers1 some kind of artificial light must be supplied4 ,that mostly used is the light of a reading oil lamp or of a gas-burner1 a candle being quite useless1 on account of the flickering of the flame with the slightest draught4 ,a moderator lamp has the defect of too great height2 otherwise this would be better than any other oil lamp4 ,a powerful and excellent light for the highest powers is afforded by a short paraffine-oil lamp4 ,as intently looking at strongly illuminated objects is injurious to the sight1 the amount of light allowed to pass the diaphragm should be no more than is agreeable1 and sufficient to show the object distinctly4 ,in using the higher powers1 the field is much less bright with the use of the same light than in the case of the lower powers2 and difficulty is often found in obtaining sufficient light for the distinct vision of the object4 ,the achromatic condenser is of most important service here2 but it is sometimes requisite1 even when this is used1 to condense the light upon the mirror by a shallow bull's-eye2 or a large common metallic reflector may be used for the same purpose4 ,the most convenient manner of proceeding in regard to the use of the individual eyes is to apply the left eye to the eye-piece1 so that the right eye may be used in finding the stage-movements1 or in moving the slide1 without removing the eye from the eye-piece4 ,if this arrangement be adopted1 the light should be placed towards the left-hand side of the microscope4 ,but the best way to avoid injuring the sight would be to use both eyes for viewing the objects in turn1 although most microscopic observers make use of one eye only for this purpose4 ,the structure of many transparent objects can be best seen when the mirror is turned more or less obliquely to one side1 so as to view them by oblique light1 as it is called3 we shall refer to this point hereafter4 ,as a rule1 objects are best seen by transmitted light1 or as transparent objects1 although it is well to examine objects under both kinds of illumination1 i4 e4 by transmitted and reflected light4 ,if during the use of the microscope1 after removing the eye from the instrument1 the impression of the light remains perceptible to the sight1 the light used has been too strong1 or its action too long continued2 and the instrument should be at once laid aside for a time4 ,,chapter ,,ii4 ,,the ,,mounting ,,of ,,objects4 ,the mounting or 8putting up0 of microscopic objects signifies their preparation in such way that they may be preserved for future reference and observation4 ,as a general rule1 objects should be mounted in that manner by which their structure is best and most clearly shown2 but in certain instances the objects are mounted so as to make their structure difficult of detection1 that they may form test-objects of the power and quality of the microscope4 ,some objects require to be mounted in the dry state1 while others are best mounted in liquid2 some again as opake1 others as transparent objects3 these must be considered separately4 ,dry opake objects were formerly mounted by gumming them upon small coin-shaped pieces or disks of cork1 blackened upon the surface with a mixture of fine lamp-black and thin warm size1 laid on with a hair-pencil4 ,they were kept in a drawer1 to the bottom of which a sheet of cork was glued1 the disk being transfixed by the pin1 so that the free or projecting pointed end of the pin could be thrust into the sheet-cork4 ,this plan may still be adopted in the case of common objects1 as seeds1 c42 but it is objectionable1 on account of the facility with which the bare objects are knocked off or injured by dust4 ,hence dry opake objects are usually mounted in such manner as to be enclosed in a cell1 the sides being formed by a ring of glass-tube or cork1 or a square piece of leather1 cardboard1 or paper1 with a hole cut or punched out of the middle4 ,the glass rings are best2 but as they are expensive1 some of the other substances are generally used4 ,the size and thickness of the material from which the rings are made must obviously vary according to the size and depth of the object4 ,the rings are cemented to the middle of ordinary slides2 and it is best to keep a number of them ready prepared4 ,the cementing material must vary according to the nature of the ring used4 ,if this consists of glass1 ,canada-balsam or marine glue is best4 ,in using the former1 the ring is gently heated over the flame of the spirit-lamp1 and a thin layer of the balsam applied to its upper or under surface1 by means of an iron wire with a little balsam on its end2 it is next warmed over the spirit-lamp1 so that the surface is entirely and evenly coated4 ,a clean slide is then slightly heated1 the ring laid upon it1 and gentle pressure is used to squeeze out the excess of balsam2 and the slide is kept at a gentle heat1 until on cooling the balsam becomes so hard as not to be indented with the finger-nail4 ,marine glue is applied in the same way as the balsam1 except that prolonged heat is not required to harden it1 for it becomes hard on cooling4 ,the balsam may also be replaced by black japan or asphalte4 ,the pieces of cork1 leather1 or paper are best fastened to the slides with solution of shellac or sealing-wax in methylated alcohol1 or with white hard varnish4 ,when the ring or piece has been firmly fixed to the slide by either of the above cementing materials1 so as to form the sides of the cell1 the bottom is to be covered with a piece of black paper1 cut to fit it exactly1 and fastened to the surface of the slide with a little gum1 or of either of the above varnishes4 ,as soon as this is thoroughly dry1 the upper surface of the cell-wall1 whether of glass or cork1 c41 is thinly covered with varnish1 and a clean thin-glass cover laid upon it1 and very lightly pressed2 the object is then permanently preserved4 ,the main points to be observed are1 that the object and varnish are completely dry1 and that the cell is thoroughly closed4 ,if the latter be not the case1 more varnish must be applied to any little openings which may have been left2 and it is better to apply the varnish in very small quantities at a time1 the application being renewed as soon as the previous layer is quite dry4 ,dry transparent objects are usually small and delicate2 for1 unless they are so1 their structure cannot be well seen4 ,in mounting these1 a square piece of note-paper or tracing-paper1 with the centre cut out1 may be fastened to a clean slide with a little paste1 gum1 or shellac varnish4 ,when this is thoroughly dry1 the object is placed in the vacant space1 a clean dry cover laid on1 and the varnish applied by means of a hair-pencil to the edges in very small quantities4 ,this will run in between the under surface of the edges of the cover and the upper surface of the paper1 and when dry will cement the two together4 ,supposing that the object is so delicate that it cannot be removed from the surface of a slide1 if it will not be injured by heat1 a good plan is to draw a square or circle around the object with a little black japan1 then to heat the slide gradually until the japan is not indented with the finger-nail when cold4 ,a clean slide is then laid upon the ring of japan1 the whole again gently warmed1 until the varnish is softened1 and the cover lightly pressed so as to be in contact all round with the varnish4 ,the slide must then be rapidly cooled1 by being laid upon a piece of metal1 which prevents the varnish from running in so as to spoil the object4 ,many dry transparent objects can be preserved by mounting in ,canada balsam4 ,this is the best process for mounting objects in general2 but only those can be so preserved which are not injured by drying1 and which are not rendered too transparent by the balsam4 ,if the object to be mounted in balsam be small1 it is thoroughly dried1 and then a drop of oil of turpentine added to it upon a slide2 the slide is then gently warmed1 which causes the turpentine to evaporate4 ,when this has nearly all evaporated1 a drop of balsam is allowed to fall upon the object from the end of a wire held at a distance above the flame of a spirit-lamp4 ,a warmed cover is next laid upon the balsam1 and gentle pressure applied until the cover is sufficiently depressed4 ,the slide is then kept at a gentle heat until the balsam is quite hard when cold4 ,the superfluous portions may be removed with the point of a knife1 and any residues cleaned off with turpentine or a little benzole on a cloth4 ,another way consists in laying a cover upon the dry object on a slide1 adding a drop of turpentine1 and warming the whole over a spirit-lamp until all air-bubbles are displaced1 then continuing the application of the heat until most of the turpentine has evaporated4 ,a drop or more of the balsam may next be applied to the edge of the cover1 when it will run in and mix with the turpentine4 ,the whole is then gently heated until the balsam is hard when cold1 more balsam being added if necessary1 to replace the turpentine which has evaporated4 ,when the objects are large1 they should be pressed as flat as possible without injury between two slides1 being retained until dry by enclosure between the prongs of an ,american clothes-peg2 or the slides may be fastened at the ends by sealing-wax4 ,when perfectly dry1 the object should be immersed in turpentine1 kept in a common gallipot1 until all the air-bubbles have been entirely displaced1 and the object appears very transparent4 ,it is then removed from the turpentine with forceps1 drained1 laid upon a slide1 and melted balsam dropped upon it until it is quite covered4 ,a clean dry slide is then laid upon its surface1 and the two slides gently pressed together1 the two slides fixed at the ends by sealing-wax1 and the whole allowed to cool and dry4 ,if requisite1 more balsam is added to fill up any vacuities4 ,when the balsam has become hard1 the excess is cleaned away with a knife and turpentine1 and the object is permanently mounted4 ,if the object should be spoiled by the presence of air-bubbles1 the slides and object should be immersed in turpentine or methylated alcohol1 until the whole of the balsam is dissolved2 the remounting may then be proceeded with as at first4 ,if the slides have been immersed in the alcohol 7which is the quickest method71 the object must be soaked in turpentine before the balsam is reapplied4 ,if1 after an object has been mounted in balsam1 on applying heat1 bubbles resembling air-bubbles should be formed1 the object must not be considered as spoiled2 for these are merely bubbles of the vapour of turpentine1 and will disappear spontaneously after a little time4 ,a quick way of mounting in balsam is to drop the melted balsam at once upon the dried object2 but as air-bubbles are very apt to be produced in this way1 the beginner had better previously apply the turpentine4 ,as balsam is very viscid1 and adheres firmly to everything with which it comes in contact1 some care is required in its use4 ,young microscopists very generally manage to soil the microscope1 tables1 chairs1 papers1 books1 and even their clothes with it4 ,it may be easily cleaned off1 however1 with turpentine or benzole4 ,moist objects are best preserved1 whenever practicable1 in glycerine4 ,there are1 however1 two important objections to its use3 one is1 that it makes objects very transparent2 the other is1 that it often wrinkles and distorts them1 by withdrawing their watery contents4 ,hence only those objects can be preserved in glycerine1 which are not too transparent1 and which are sufficiently firm to resist the tendency to collapse4 ,when the objects are tolerably flat1 and sufficiently firm to bear the pressure of the cover1 they may be mounted by adding a small quantity of glycerine to them lying on a slide2 the cover is then applied1 and a little of the cement mentioned below applied warm with a hair-pencil around the edges of the cover to fasten it to the slide4 ,care is required that the glycerine applied be no more than sufficient2 for wherever it has touched the cover or the slide1 the cement will not adhere4 ,superfluous portions may be sucked up with a piece of clean moist sponge or a corner of blotting-paper4 ,when it is required to mount a large number of objects in a short time1 the cement need only be applied to two opposite sides of the cover1 leaving the other two sides open4 ,when the objects require to be protected from the pressure of the cover1 the sides of a cell must be made with the cement or black japan upon the slide before the cover is applied1 a further quantity being used to close the cell as usual4 ,a very strong solution of chloride of calcium may be used for the same purposes and in the same way as the glycerine4 ,it has the advantage of not making the object so transparent2 but it has the disadvantage of crystallizing slightly in a dry atmosphere4 ,in most cases1 ,i prefer it to glycerine4 ,a large number of interesting objects cannot1 however1 be preserved in either glycerine or chloride of calcium1 without their value being impaired by the cause mentioned above4 ,many kinds of liquid have been recommended for preserving these1 all agreeing mainly in being inefficient4 ,the objection to them is1 that they are evaporable2 and after the object has been mounted for some time1 the liquid creeps between the cement and the slide or cover1 at some spot1 and evaporates2 and if the cement be not quite hard1 the inner and more liquid portion of it runs into the cell1 and spoils the object4 ,a solution1 containing a grain of salt and a grain of alum to the ounce of distilled water1 is as good as any other2 or simply distilled water in which a piece of camphor has been kept4 ,in use1 the cell is first formed by making a circle or outline square on the slide with black japan1 and heating this carefully until it becomes solid when cold4 ,the object is then laid in the cell1 the liquid added1 and the cover applied1 any excess being removed with blotting-paper4 ,the cell is to be closed with old black japan or gold-size1 applied round the margins of the cover with a hair pencil4 ,a second and a third layer of the varnish may be applied upon the first1 when it has become hard outside4 ,although black japan and gold-size are generally used for the cement1 ,i prefer that mentioned below4 ,when large preparations are mounted in liquid1 the cell-walls are either formed of glass rings1 or they are built up with four oblong pieces of glass1 cemented to the slide and to each other with marine glue4 ,a very good preservative liquid for large specimens is a solution of chloride of zinc1 in the proportion of #bj grains to the ounce of distilled water4 ,a mixture of spirit of wine and water1 in the proportion of #a part to #b1 or #a to #d1 is often used for the same purpose4 ,when preparations are mounted1 the cement and the adjacent parts of the slide and cover should be coated with a solution of sealing-wax in spirit1 which hardens the exterior of the cement4 ,the cement above alluded to is made by melting together #e parts of rosin1 #b parts of balsam1 #a part of bees'-wax1 and #a of red ochre4 ,the cement is best kept in a little metallic cup1 and melted over a spirit-lamp when used4 ,it should be applied while hot1 with a hair pencil2 and cools very quickly4 ,the preservative liquids should be kept in corked bottles1 a hair pencil being fixed into the under part of the cork2 or1 what is better1 in stoppered bottles1 the stopper being prolonged to a point nearly reaching the bottom of the bottle4 ,as soon as the preparations are mounted1 they should be labelled1 the labels being kept ready gummed4 ,the balsam should be kept in a capped bottle1 such as is used for holding solutions of gum1 with an iron wire for removing portions as required4 ,by keeping1 the balsam becomes thicker2 it may be thinned by the addition of oil of turpentine1 and the application of a gentle heat4 ,the black japan1 c41 may be procured at any oil-shop2 the glass rings1 cell-sides1 covers1 c41 from ,mr4 ,norman1 #agh ,city ,road1 or of the microscope-makers4 ,mounted objects should be kept in shallow drawers1 and be laid flat--not standing on edge4 ,magnifying power4--,before entering upon the consideration of the objects themselves1 a word or two must be said upon the magnifying powers4 ,in the plates of this work1 the serial number of each figure is expressed by large numerals placed above the objects1 while the number of times the object is magnified is indicated by small numerals placed beneath4 ,the latter must be understood to express the number of times the drawing is larger than the object in one dimension4 ,thus1 considering fig4 #ac1 ,plate ,i4 to be an inch in width 7for it is really somewhat less71 being magnified #aej times in the direction of the width1 the object itself is about #a_/aejth of an inch in size2 and it is represented magnified #aej times linear1 or #aej diameters1 as it is called4 ,a knowledge of the number of times the object is magnified is of the greatest importance in making use of the drawings2 for1 without it1 the observer will be unable to apply such a magnifying power of the microscope as will enable him to see the structural appearances figured in the drawings4 ,the observer must also be acquainted with the magnifying powers of his microscope with the various object-glasses and eye-pieces4 ,these are usually given when the instrument is purchased4 ,or they may be determined approximatively thus3--,an ivory scale1 with #a_/ajjth of an inch engraved upon it1 is placed on the stage1 and viewed as an opake object1 both eyes being kept open2 and the size of the image of one of the gradations is measured with compasses1 upon the stage as seen with that eye which is not applied to the eye-piece4 ,the number of #a_/ajjths of an inch contained in the measure obtained with the compasses represents the magnifying power4 ,thus1 supposing the image of the #a_/ajjth of an inch on the scale appears magnified to the length of #a inch on the stage2 the magnifying power is #ajj diameters1 or #ajj times linear4 ,this proceeding is difficult to any one unaccustomed to the use of the microscope1 yet by practice it becomes very easy4 ,other methods1 which require the use of the camera lucida1 are given in the ,micrographic ,dictionary4 ,,chapter ,,iii4 ,,vegetable ,,elements ,,and ,,tissues4 ,we may now enter upon the consideration of the microscopic structure of objects1 beginning with those which are derived from the vegetable kingdom1 as they are more easily procured and prepared for examination than those belonging to the animal kingdom2 moreover they are not so transparent1 and hence are more readily distinguished under the microscope1 which is of importance in the case of an unpractised observer4 ,cells4--,the elements of which all plants consist are cells4 ,cells1 in their simplest condition1 are microscopic1 rounded1 colourless1 closed sacs or vesicles1 resembling small bladders 7,plate ,i4 fig4 #b71 and consist of a thin1 transparent1 colourless1 vegetable skin or membrane 7a7 called the cell-wall4 ,the cells are well seen in a little of the pulp of an apple 7fig4 #b71 or in a section of almost any soft part of a plant4 ,a high power is usually required to show them distinctly1 on account of their minute size4 ,the outline of the cells is seen to be double1 one line indicating the inner1 the other the outer1 surface of the cell-wall1 the space between the two lines corresponding to the thickness of the cell-wall4 ,in the pulp of the apple1 the cells are loosely connected1 and so retain their rounded form2 but in most parts of plants1 the cells become crowded and squeezed together1 from their ordinary or normal expansion being limited in certain directions1 so as mutually to alter each other's shapes4 ,the sides then lose their originally rounded form and outline1 becoming more or less straight 7,pl4 ,i4 figs4 #a #d71--the cells at the same time mostly adhering to each other1 so as to be separated with difficulty4 ,the forms thus produced are various and interesting1 and have all received names by which they are distinguished4 ,they are described in works on botany in two ways--according to the outline 7which is the most common1 as this expresses the appearance usually presented in sections and on the surfaces of vegetable structures71 or according to the entire or solid form1 which it is often a difficult matter to determine4 ,cellular tissue4--,cells aggregated thus form a tissue1 which is called cellular tissue or parenchyma 71 among1 and 1 poured substance71 because it fills up the interstices of the other tissues of plants4 ,in technical descriptions1 the cell-structure is often left out of consideration2 and bodies composed of parenchymatous tissue are described as being reticulated or netted1 because the united sides of the cell-walls appear as a network covering the surface4 ,it must be understood that parenchymatous cells are such only as have the three dimensions of solidity 7viz4 the length1 breadth1 and depth7 nearly equal4 ,intercellular passages4--,the observer will not have examined many sections of cellular tissue1 without noticing certain irregular black lines running between the cells1 as in a piece of a ,geranium-7,pelargonium-7 leaf 7,pl4 ,i4 fig4 #a74 ,these lines arise from the existence of passages between the cells1 containing air2 and they are called intercellular passages4 ,by gently warming a section containing them in water over a spirit-lamp1 or by moistening the section with a drop of spirit1 the passages will be filled up with the liquid1 so as to become transparent4 ,when the intervals between the cells are larger and broader1 they are called intercellular spaces4 ,so far1 cells have been considered simply in regard to their form1 as vesicles1 either rounded or altered in shape by mutual pressure4 ,we have now to notice the matters contained within the cells1 or the cell-contents4 ,cell-contents4--,in most cells1 especially when young1 a minute1 rounded1 colourless body may be seen1 either in the middle or on one side1 called the nucleus2 this is very distinct in a cell of the pulp of an apple 7,pl4 ,i4 fig4 #b b74 ,and within this nucleus is often to be seen another smaller body1 frequently appearing as a mere dot1 called the nucleolus4 ,the nucleus is imbedded in a soft substance1 which fills up the entire cell 7,pl4 ,i4 fig4 #b c72 this is the protoplasm 71 first1 1 formative substance74 ,as it is very transparent1 it is readily overlooked2 but it may usually be shown distinctly by adding a little glycerine to the edge of the cover with a glass rod1 when it contracts and separates from the cell-walls1 as in the lower cell of fig4 #b4 ,the protoplasm in some cells is semisolid and of uniform consistence1 while in others it is liquid in the centre1 the outer portion being somewhat firmer and immediately in contact with the cell-wall4 ,in the latter case1 it forms an inner cell to the cell-wall1 and is called the primordial utricle4 ,the terms 8protoplasm0 and 8primordial utricle0 are1 however1 used by some authors synonymously4 ,the protoplasm is the essential part of the cell1 and it forms or secretes the cell-wall upon its outer surface in the process of formation of the cell considered as a whole4 ,it is also of different chemical composition from the cell-wall1 being allied in this respect to animal matter4 ,chlorophyll 71 green2 1 leaf74--,on examining a section of any green part of a plant1 as the green substance of a ,geranium-7,pelargonium-7 leaf1 it will be seen that the green colour does not arise from the whole substance being coloured1 as appears to be the case to the naked eye1 but from the presence of little grains or granules of a green colouring-matter in the protoplasm of the cells4 ,this green matter is called chlorophyll4 ,if the cells be crushed1 the granules will escape1 and can be examined in the separate state4 ,chlorophyll is most abundant in those parts of plants which are exposed to the light4 ,starch4--,in many cells of plants1 particularly those which have attained their full growth1 other granules1 larger than those of chlorophyll1 and colourless1 are met with2 these are the starch-granules 7,pl4 ,i4 fig4 #c74 ,they are usually rounded or oblong1 and exhibit on the surface a number of rings1 one within the other1 or concentric1 as it is called4 ,in the centre of the innermost ring is a black dot or streak1 arising from the presence of a little pit or furrow1 and called the hilum4 ,the starch-grains may be readily seen within cells in a thin section of a potato 7,pl4 ,i4 fig4 #d72 here they are very numerous1 and larger than in most other plants4 ,a separate grain is represented in fig4 #c4 ,the appearance of rings in the separate grains arises from the starch-granules being composed of numerous concentric coats or layers1 like those of an onion4 ,a very simple and striking method of determining whether any granule is composed of starch or not1 consists in adding to it1 when placed in water on a slide1 a drop of solution of iodine4 ,as soon as this touches the granule1 it assumes a beautiful purple colour1 the depth of tint depending upon the quantity of the iodine-solution2 if this be very considerable1 the granule appears almost black4 ,the section of potato forms a very interesting object when moistened with the iodine-solution1 the starch-granules becoming beautifully coloured1 whilst the cell-wall remains colourless1 and the protoplasm becomes yellow4 ,the form of the starch-granules differs in different plants1 so that the kind of plant from which starch has been derived may be distinguished by attention to the size1 form1 and structure of its starch-granules4 ,thus1 the granules represented in ,pl4 ,i4 fig4 #c1 which it will be noticed are all drawn under the same power1 are derived from different plants1--a being those of wheat-flour1 in which the hilum is obscure1 and the rings faint2 b is a granule of ,west ,indian arrowroot1 in which the hilum forms a transverse crack2 c is a granule of potato-starch1 in which the hilum is a dot1 and the rings are very distinct2 d represents the compound granules of the oat1 the separate granules being figured below2 e is a granule of lentil-starch1 with its long dark hilum and elegant oval concentric rings2 and f represents a compound and separate granule of rice-starch4 ,it will be noticed that the granules of oat-and rice-starch are angular1 as it is called4 ,the knowledge of the peculiar forms of the starch-granules is important in a practical point of view1 for it enables us to recognize them when mixed as an adulteration with other substances1 and also to distinguish the different kinds of starch from each other4 ,thus table-mustard1 as it is called1 is principally composed of the cheaper wheat-or pea-flour1 which is easily recognized by the structure of the starch-grains4 ,arrowroot is considerably dearer than potato-starch2 hence in trade the latter is fraudulently sold for the former1 the adulteration being detected with difficulty by the eye1 but easily under the microscope4 ,again1 rice is largely mixed with wheat-flour1 as it makes inferior flour into very white bread2 and this may also be readily detected under the microscope4 ,the reader can now understand how valuable the microscope is in detecting adulterations1 with a knowledge of the various forms and structures of substances1 especially with the aid of a few chemical tests4 ,starch-grains are altered by boiling in water1 becoming swollen and often changed into curious forms1 the rings becoming faint or disappearing4 ,if a piece of boiled potato be examined1 the starch-granules will seem to have vanished from the cells1 which are swollen and covered with an irregular kind of network4 ,the network consists of parts of the protoplasm situated in the interstices of the starch-granules1 and solidified or coagulated by the heat4 ,on crushing the cells by pressing upon the cover1 the starch-granules will escape1 swollen and partly fused together2 but they may easily be recognized as consisting of starch by the iodine test4 ,the granules of 8tous les mois0 starch are particularly well adapted for showing the concentric rings1 the granules being about twice as large as those of the potato4 ,starch-granules are best examined in water2 and a small quantity only of the starch must be placed on the slide1 if the structure of the granules is to be seen clearly4 ,they may be mounted in glycerine1 although this makes them very transparent4 ,to those who possess a polariscope1 starch-granules are particularly interesting1 as they exhibit a black cross1 and1 with a plate of selenite laid beneath the slide1 a beautiful play of colours4 ,in addition to the starch and chlorophyll1 the cells of plants contain other matters1 as gum1 sugar1 c42 but as they are dissolved in the cell-liquid1 they are not visible4 ,in the cells of certain plants1 however1 spherical globules1 with light centres and black outlines1 will be met with3 these consist of oil4 ,raphides4--,lastly1 occurring in the cells of plants1 especially such as are soft and juicy 7succulent71 will be found minute1 hard1 colourless crystals1 called raphides 71 a needle74 ,these are most frequently needle-like or acicular 7acus1 a needle71 but sometimes prismatic or rod-like with flat sides2 they are also not unfrequently grouped into little tufts4 ,they may be readily found in a piece of the stem of garden-rhubarb 7,pl4 ,i4 fig4 #e a71 or of the common balsam4 ,porous and spiral cells4--,the walls of the cells of cellular tissue are sometimes covered with little dots 7,pl4 ,i4 fig4 #aa a71 or slit-like markings2 the cells are then called porous cells4 ,a specimen of them may be obtained from a section of the pith of the elder 7,sambcus ngra74 ,sometimes cells exhibit the appearance of a spiral line marking their walls1 as if a little bell-spring were coiled up in them 7,pl4 ,,iii4 fig4 #b a74 ,these are called spiral cells1 or spiral fibrous cells1 and the tissue formed by them is called fibro-cellular tissue4 ,we now leave the cells of ordinary cellular tissue1 to examine those in which the dimension of length predominates1 so that they form tubular cells2 and first of those required to possess strength and firmness1 combined with flexibility4 ,these qualities are met with in the cells constituting ,woody tissue4--,of this there are two forms1 called respectively wood-cells and woody fibres4 ,the wood-cells are moderately long1 more or less tapering and overlapping at the ends2 and the cell-walls are thickened1 so as to possess considerable firmness4 ,these cells are found in the wood of stems1 as in the white woody portion of an ash stick1 that of a lime-tree1 the stem of a ,chrysanthemum1 c4 7,pl4 ,i4 fig4 #f74 ,they are closely packed1 and the tissue formed by their union is called prosenchyma 71 close1 1 tissue74 ,in the other kind of woody tissue the cells are very long and slender1 strong1 yet flexible1 gradually tapering at the ends1 where they overlap each other2 and they have thick walls1 so that1 when divided transversely1 the cavity appears almost filled up 7,pl4 ,i4 figs4 #e d1 #i1 #g b74 ,this tissue is called woody fibre or pleurenchyma 71 rib1 71 from its strength4 ,the walls of the cells of woody tissue are often covered with dots1 either simple or with an inner dot 7,pl4 ,i4 fig4 #f b1 fig4 #aa b71 or with streaks 7,pl4 ,i4 fig4 #f a7 or with a spiral fibre 7fig4 #aa b1 c71 either alone or with dots also4 ,this tissue is of great importance in plants1 from its strength and flexibility2 it forms a considerable part of the veins of leaves1 the inner bark 7liber71 and of the wood of the stems of trees4 ,it is also very useful to man3 for it constitutes hemp1 of which rope and string are made2 flax1 of which linen is made2 cocoanut fibre2 bast1 used by gardeners for tying up plants1 which is the inner bark of the lime2 and jute1 which is the inner bark of an ,indian lime-tree4 ,in the white woody part of the stems of trees belonging to the fir-order 7,conifer71 as a piece of deal or pine1 which is mainly composed of wood-7prosenchymatous7 cells1 the cells exhibit rows of minute circular markings 7,pl4 ,i4 fig4 #aj74 ,these were formerly supposed to be solid bodies or glands2 hence the tissue is still sometimes called glandular4 ,within the outer ring of each marking is an inner central dot1 or sometimes an oblique streak4 ,the side view of the cells 7,pl4 ,i4 fig4 #h a71 which is seen in a tangential section1 shows that the markings are minute pits1 each being opposite to one of an adjacent cell1 and sunk inwards towards the centre of the cell1 the inner dot or streak being a thinner portion of the cell-wall4 ,this glandular tissue of the ,conifer is interesting as forming a test-object for the defining power of the microscope1 which should show the two rings sharply and free from colour2 the section of the wood should be examined as a dry transparent object4 ,the difference between the woody fibre and the wood-cells of coniferous wood may also be seen well in a piece of deal1 as cut up for fire-wood4 ,if the end of a stick of this be examined with the naked eye1 parts of brown rings will be seen traversing the whiter portion of the wood4 ,these brown rings consist of woody fibre2 the white portion of wood-cells4 ,on making a very thin transverse section1 the interior of the woody fibres is seen to be almost entirely filled up 7,pl4 ,i4 fig4 #g b71 while the cavity of the wood-cells is much more open 7,pl4 ,i4 fig4 #g a72 the former also contain globules of turpentine4 ,it must be remarked here that some botanical authors include both forms of woody tissue under the term prosenchyma4 ,but1 as we shall see hereafter1 the form of the prosenchymatous cells being sometimes used as a character for distinguishing the cells of leaves1 to which the term pleurenchymatous cells would be inapplicable1 the above distinction will be found important4 ,vessels1 vascular tissue4--,in the next form of tubular cells1 these are broader and softer than the cells of woody tissue1 thin-walled1 and the ends pointed2 and their walls exhibit spiral or ring-like markings1 or rows of dots 7,pl4 ,i4 fig4 #e c1 e1 b71 indicating the existence of one or more spiral fibres or rings4 ,when the vessels contain spiral fibres1 they are called spiral vessels 7,pl4 ,i4 fig4 #e c72 when they contain ring-shaped portions of fibre1 they are called annular 7annulus1 a ring7 vessels 7,pl4 ,i4 fig4 #e e72 and when the spaces between the fibres are partly filled up1 leaving only dots1 the deposit forming a kind of network1 we have a reticulated 7rte1 a net7 vessel 7,pl4 ,i4 fig4 #e b74 ,this tissue can easily be obtained from a piece of cooked rhubarb1 the stem of a balsam1 or from any soft-stemmed plant4 ,vessels very frequently contain air4 ,ducts4--,the tubular cells forming ducts 7,pl4 ,i4 figs4 #e b1 #aa c7 are large1 more or less flattened or blunt at the ends 7truncated72 and the cell-membrane at first closing the ends is often removed or absorbed1 so that the ducts communicate with each other1 to allow of the free passage of the sap through them4 ,their walls are invariably covered with markings1 consisting of either simple or bordered dots1 resembling those met with in the preceding forms of tissue4 ,the ducts are often easily recognizable with the naked eye1 in transverse sections of stems1 by the large pores which they form in the wood4 ,these may be well seen in a section of a piece of cane4 ,the tissue composed of dotted ducts is called bothrenchyma 71 pit72 but the term is principally applied to those ducts in which the dots are simple1 i4 e4 have no inner dot4 ,the structure of the above forms of tissue may be best understood in relation to their development4 ,it has been stated that the essential part of the cell is the protoplasm4 ,as cells grow older1 new matter is deposited by the protoplasm upon the inner surface of the cell-wall1 either to a small extent1 evenly and uniformly1 as in ordinary parenchyma1 or unevenly1 in the form of spiral layers1 forming fibres or bands1 leaving bare spaces1 where the original cell-wall exists alone4 ,the matter thus deposited is called secondary deposit1 the original cell-wall being the primary deposit4 ,when the secondary deposit covers the interior of the cells except at certain slit-like spaces1 we have the appearance figured in ,pl4 ,i4 fig4 #f a4 ,when the deposit forms a spiral fibre1 or a series of rings1 we have the spiral or annular vessel or duct4 ,and when the interspaces between the coils of a close spiral fibre are filled up except at certain spots1 we have the dotted or reticulated vessel or duct4 ,in many instances1 these deposits are present together3 thus1 sometimes the outermost deposit leaves rounded pits or dots1 while an inner portion forms a spiral fibre 7,pl4 ,i4 fig4 #aa b72 or one layer leaves simple rounded pits1 while the other leaves smaller slits or dots placed opposite the former 7,pl4 ,i4 fig4 #f b74 ,in some cells the cavity is almost entirely filled up by secondary deposit1 which leaves minute canals radiating from a small cavity in the centre to the circumference1 as seen in the transverse section of a plum-stone 7,pl4 ,i4 fig4 #ef72 here the canals appear as dark lines4 ,in others1 again1 the secondary deposit forms several distinct layers1 leaving channels very similar to those of the last2 an example is met with in the gritty tissue of the pulp of a pear4 ,the obvious use of the pits and channels in the above tissues is to preserve the permeability of the walls of the elements1 which would be destroyed if the walls were equally thickened all over4 ,cell-formation4--,new cells are formed by the division of old or parent cells4 ,the actual process of division is difficult to observe1 as it requires prolonged observation2 but cells are often met with in all stages of division1 of which some instances will be pointed out hereafter4 ,the cell-division takes place in two ways1 either according to the endogenous 71 within1 1 to produce71 or the exogenous 71 outside1 7 method4 ,the manner in which the division takes place in the former is this3--,at first a slight indentation or constriction of the protoplasm occurs at the line of division2 this deepens until the protoplasm is completely divided4 ,the freshly divided surfaces then become coated with a new portion of cell-wall1 so as to make two or more new cells1 which either remain in contact or separate from each other4 ,in some cases1 the divided portions of protoplasm become coated all over with new cell-walls4 ,in the exogenous process1 a portion of the protoplasm protrudes from the surface of the cell1 carrying the cell-wall before it1 so as to form a little bud-like body2 this is next cut off at its point of junction with the parent-cell1 and coated1 as in the first case1 with a new cell-wall1 so as to form a new cell4 ,preparation4--,in examining the vegetable elements and tissues1 very thin sections must be made with a razor or thin sharp knife2 these are then to be placed in a little water on a slide4 ,as the structures are all minute1 the distinctness with which they are seen will mainly depend upon the proper thinness of the sections4 ,when sections of dry stems are to be examined1 the black margins of the air-bubbles contained in the cells often render the structure indistinct2 these must therefore be displaced by first wetting the tissue with methylated alcohol1 and then adding water to it in a watch-glass or on a slide2 or the tissue may be soaked in warm water for some hours3 and this is mostly requisite in preparing thin sections of dry tissues4 ,attention must also be paid to the manner in which the section is made1 or the direction in which the portion of the plant is cut4 ,there are three important directions which must be distinguished1 producing transverse1 longitudinal1 and tangential sections4 ,if the cuts be made across the length of a stem1 for instance1 the section is called transverse4 ,if the cuts be made in the direction of the length1 through the centre1 the section is longitudinal2 and if the cuts are made in a direction parallel to a line running down the centre of the stem1 but nearer its margin1 it is a tangential section4 ,it is scarcely necessary to mention that an oblique section is intermediate between a transverse and a longitudinal section4 ,,chapter ,,iv4 ,,vegetable ,,organs4 ,the vegetable elements and tissues which have been described form1 either separately or by their combination in various ways1 the organs of plants4 ,to these we shall now pass1 and consider the structure of the principal organs of the members of the vegetable kingdom4 ,leaves4--,leaves in their simplest form consist of a single sheet or layer of parenchymatous cells or cellular tissue1 an example of which may be found in almost any moss 7,pl4 ,,iii4 fig4 #cj74 ,the granules of chlorophyll will often be very distinctly seen in these cells4 ,the first addition to this form of leaf is a row or two of prosenchymatous cells running longitudinally down the middle of the leaf1 so as to form a rudimentary vein or nerve4 ,in other and more highly developed leaves1 the layers of cells are numerous1 and traversed by bundles of wood-cells1 vessels1 and ducts 7fibro-vascular tissue71 forming the veins1--the entire surface being covered with a skin or membrane1 called the epidermis4 ,epidermis 71 upon1 1 skin74--,this membrane is composed of one or more layers of colourless1 closely packed cells 7,pl4 ,i4 figs4 #ac #bh71 the colour it occasionally exhibits usually arising from some of the underlying cells of the leaf being seen through it1 or remaining adherent to it when stripped from the leaf4 ,it is easily separated1 by making a cut in a soft leaf1 and peeling it off with a fine pair of forceps1 or by soaking a leaf for some time in water and then stripping it off4 ,it must be remarked that the epidermis covers not only the leaves1 but every part of the plant4 ,hairs4--,arising from the epidermis are the hairs of plants4 ,these are thread-like or filamentous prolongations of the epidermis beyond the surface of the leaf 7,pl4 ,i4 fig4 #ab71 consisting of cells arranged end to end4 ,they are often branched1 sometimes star-shaped 7stellate7 7fig4 #bh71 and present great varieties in form1 as shown in the figures1 the plants from which these were drawn being mentioned in the ,description of the ,plates4 ,sometimes hairs terminate in a little head 7,pl4 ,i4 figs4 #ab c1 d1 e71 the cell or cells composing which secrete a colouring or a viscid substance2 they are then termed glandular4 ,the hairs of plants are particularly interesting to the microscopic observer1 not only on account of their curious forms1 but in connexion with the remarkable phenomenon of the circulation of the cell-contents1 or rotation1 as it is called1 observable in them4 ,this is difficult to be perceived by any one unaccustomed to microscopic observation1 because the particles by which the motion of the cell-contents becomes evident are exceedingly minute2 but practice in the use of a high power will overcome this difficulty4 ,the hairs which exhibit the phenomenon best are those of the ,american ,spiderwort 7,tradescantia ,virginica71 which is to be found in every garden4 ,it may1 perhaps be recognized thus3--,the plant is about a foot and a half high2 the leaves are sword-shaped and channelled1 and the flowers are purple1 in heads1 and #a inch in diameter4 ,the hairs are attached to the sides of the stamens1 towards the lower part or base4 ,the stamens should be carefully picked off with forceps1 and placed on a slide in a drop of water2 the hairs should then be separated with the mounted needles1 and a cover applied4 ,under a low power1 the hairs are seen to be beaded or moniliform 7monle1 a necklace71 and of a fine purple colour 7,pl4 ,i4 fig4 #bb74 ,on applying a high power1 as the -inch1 the individual cells will come distinctly into view1 and the nucleus will be seen very clearly as a roundish granular mass 7,pl4 ,i4 fig4 #bc a74 ,on carefully examining the cell-contents1 delicate lines will be observed radiating irregularly from the nucleus1 some passing to the top of the cells1 while others run towards its base1 as in the figure2 and on very close inspection1 the portions of protoplasm of which these lines consist1 will be found to move slowly and steadily1 the motion becoming perceptible by means of the minute granules of which the protoplasm consists4 ,the currents return at the ends of the cell1 there being no passage of the contents of one cell into the cavity of either of those adjacent4 ,during this examination1 it will be noticed that the surface of the cell-wall is striated with fine wrinkles4 ,it may be remarked that the hairs should be taken from flowers which have only just opened2 for this curious and inexplicable rotation is connected with the growth of the cell2 and when this has attained maturity1 it no longer occurs4 ,the phenomenon may be observed in many other hairs of plants1 as those of common groundsel 7,sencio vulgris7 7,pl4 ,i4 fig4 #ab a1 b71 and in the cells of the leaves of some water-plants2 but ,i must refer to the article 8,rotation0 in the ,dictionary for further information4 ,the most important variety of hair is that derived from the ,cotton-plant 7a kind of ,mallow71 and forming the cotton of commerce4 ,these hairs spring from the epidermis of the seeds4 ,the cells composing it are very long and soft1 becoming flaccid and easily bent when dry 7,pl4 ,,ix4 fig4 #ac74 ,stings4--,stinging hairs or stings may be well illustrated by reference to the common large nettle 7,urtca dioca74 ,in this plant they consist of a thick-walled cell1 bulbous at the base1 which is imbedded in the epidermis 7,pl4 ,i4 fig4 #ba71 the pointed end being terminated by a very minute dilatation or knob4 ,the sting contains an acrid liquid1 which escapes when the little knob is broken off in wounding the skin1 and produces the well-known irritation4 ,by the side of the figure of the sting is represented the point of a fine needle 7fig4 #bj71 showing that the expression 8sharp as a needle0 has no force when microscopic bodies are in question4 ,stomata 71 mouth74--,on viewing a strip of epidermis1 the observer will be sure to notice certain oval or roundish bodies 7,pl4 ,i4 fig4 #ac a71 composed of mostly two kidney-shaped cells in apposition but leaving a chink between them2 these are the stomata4 ,they communicate beneath with the intercellular passages1 of which they may be considered the mouths2 and by their agency a direct communication is established between these passages and the air4 ,the two cells which guard the orifice are termed the 8guard cells40 ,stomata are most numerous on the under surface of leaves2 they are entirely absent in plants growing under water1 and in most of the lower plants4 ,in many of the stomata1 viewed in the ordinary way1 the air situated between the guard cells is indicated by the black spot or dot present2 but after a time1 or by the application of a gentle heat to the slide1 the air becomes displaced by the water1 and their structure becomes very distinct4 ,in certain plants1 the epidermis is imbued with flint or silica2 so that even when burnt to an ash the stomata are still quite distinct4 ,examples of this may be found in the stalk or culm of grasses1 as in straw1 the shining epidermis of which is siliceous2 or the epidermis of canes4 ,among the lower plants1 this peculiarity is especially curious in the species of ,equistum1 or mares'-tails4 ,the manner in which the veins of leaves are arranged is worthy of special attention1 as it forms one of the characters by which the two leading divisions of the ,vegetable ,kingdom are characterized4 ,thus in one of these divisions the veins are branched1 so as to form a network throughout the leaf2 the plants with these netted veins1 to which belong our trees1 shrubs1 and most herbs1 are the ,dicotyldons1 or ,exogens2 while in the second division1 the veins run parallel to each other1 being little or not at all branched1 and not forming a network4 ,the plants with parallel veins1 among which are our grasses1 lilies1 c41 are the ,monocotyldons or ,endogens4 ,stems4--,in the stems of plants1 the tissues are arranged round a centre2 otherwise1 in the simpler and lower plants1 they agree in structure with leaves1 the centre being occupied by some element of fibro-vascular tissue1 as simple wood-cells1 a few vessels or ducts4 ,in the higher or flowering plants1 the stem exists in two distinct forms1 corresponding to the differences above noticed in the arrangement of the veins of the leaves2 these must be considered separately4 ,in the ,dicotyledons or ,exogens 7,pl4 ,i4 fig4 #cf71 the centre of the stem1 in a transverse section1 is seen to be occupied by the pith or medulla1 which is represented in the figure by the innermost circle4 ,immediately outside and around this is a narrow ring1 indicating the section of a sheath to the pith1 and called the medullary sheath4 ,next comes a broad ring of wood of the first year's growth 7fig4 #cf a71 traversed1 from the pith to the bark1 by wedge-shaped paler rays1 termed the medullary rays4 ,outside the first year's wood is the newer and paler wood of the second year 7b72 and so on1 a new ring of wood being added outside the preceding layer for each year of growth of the stem4 ,on the outer side of the wood is the inner bark or liber 7fig4 #cf c72 and outside this is the spongy outer bark 7d71 covered by its epidermis4 ,these structures are of different composition1 as may be best seen in longitudinal sections4 ,the pith and the medullary rays consist of cellular tissue1 the cells being mostly rounded in the former1 and more closely pressed together and squarish in the latter4 ,the medullary sheath consists of vascular tissue2 and the wood1 of wood-cells traversed longitudinally by bundles of vascular tissue and ducts1 the latter being larger and more distinct towards its outer boundary4 ,the liber is composed of woody fibre1 and the outer bark of cellular tissue4 ,the new woody matter being deposited outside the old1 between the bark and the previously formed layer1 gives origin to the term exogen 71 outside1 1 to produce74 ,these structures may be examined in the section of a branch of the lime-tree or lilac4 ,in the ,monocotyledons or ,endogens 7,pl4 ,i4 fig4 #cg71 there is no distinct bark1 nor pith1 nor medullary rays--the entire stem consisting of cellular tissue with isolated bundles of fibro-vascular tissue scattered through it4 ,moreover the new substance is added to the centre of the stem1 or within the old2 hence the term endogen 71 within1 74 ,a section of a piece of cane will exhibit this structure4 ,to examine the structure of stems1 sections must be made in various directions4 ,the relative position of the component parts of a stem are best seen in a transverse section2 but the structure of the tissues is most evident in longitudinal sections1 and under the higher powers4 ,the annual rings of the ,exogens are best observed in transversely sawn-off pieces of perfectly dry stems1 which have been polished with sandpaper1 and varnished with spirit varnish4 ,roots4--,the structure of roots is very similar to that of stems2 there is1 however1 no distinct pith1 nor are there stomata on the epidermis2 and the vessels are replaced by ducts4 ,the very fine rootlets or radicles of water-plants often show the rotation of the protoplasm very distinctly4 ,flowers4--,the various parts of flowers1 being each a modified leaf1 present the same general structure as the latter4 ,as the reader may not be acquainted with the names of these parts or organs in the higher plants1 and as we shall have to compare them with their representatives in the lower forms of vegetable life1 it will be well briefly to indicate them4 ,a common and beautiful yet despised flower 7,pl4 ,i4 fig4 #cb7 may serve for illustration2 this is chickweed 7,stellria mdia71 which can be found everywhere4 ,the outermost circle of flower-leaves1 which forms a kind of cup to the rest of the flower 7a71 is the calyx2 the separate leaves being called the sepals4 ,the row within this1 in most flowers consisting of brilliantly coloured pieces1 forms the corolla 7b72 the individual pieces being the petals4 ,when the two kinds are equally coloured1 or not distinguishable1 the whole is called the perianth1 as in a tulip4 ,when the segments of the perianth are dry and chaffy1 as in the flowers of grasses1 the outermost are said to constitute the glumes1 and the innermost the pale4 ,within the ring of petals are certain thread-like organs called stamens 7c72 and these consist of a filament 7fig4 #ci a71 surmounted at the top or apex by the anther 7fig4 #ci b71 which is usually coloured1 and consists of two lobes4 ,the anthers when ripe burst1 and discharge a coloured dust2 this is the pollen4 ,lastly1 within the stamens is the central organ of the flower1 the pistil1 and sometimes there are several of them4 ,the pistil consists of three parts1 viz4 a swollen base1 the ovary 7fig4 #da b71 surmounted by a column or style 7fig4 #da a71 and which is crowned by a viscid and often hairy summit1 the stigma 7fig4 #dj9974 ,in chickweed there are #c styles4 ,it must be remarked that1 in the flowers of some plants1 stamens alone are present1 while others contain pistils only1 although most flowers contain both organs4 ,when the stamens and pistils occur in separate flowers on the same plant1 the plant is said to be moncious 71 single1 1 family72 when all the flowers of distinct plants contain either stamens only or pistils only1 the plant is dicious 71 twice1 72 and when the stamens and pistils occur together in all the flowers of the same plant1 the plant is said to be hermaphrodite4 ,these terms had their origin in the idea that the differences of plants in respect to these organs were analogous to those of the sexes in animals4 ,all the parts of a flower have their special uses3 thus the calyx and corolla protect the delicate organs enclosed by them1 until they attain maturity4 ,the petals also1 by their brilliant colours1 attract insects which feed upon or collect the honey of the flowers2 these at the same time conveying the pollen which adheres to their bodies from one flower to the stigma of another4 ,the stamens and pistils are organs of fructification1 it being essential for the fertilization of the flowers that the pollen should come into contact with the stigma4 ,we will now consider some interesting points of structure in these organs4 ,petals4--,the petals often form most beautiful microscopic objects1 on account of the curious shape and structure of the cells of their epidermis1 and the splendid tints of the colouring matters contained in them4 ,as petals are mostly too thick to allow of the cells being distinctly seen in the entire state1 a little cut should be made in them while gently stretched on the finger1 and the epidermis carefully stripped off with forceps2 the strip should then be laid on the slide in water as usual3 in this way the curious patterns of the epidermic cells will become very distinct4 ,the petals of a red geranium 7,pelargnium7 may be used to illustrate them 7,pl4 ,i4 fig4 #bd74 ,the structure may be best understood by reference to the epidermis of the leaf of a geranium 7,pl4 ,i4 fig4 #ac71 in which the cells present wavy or undulate walls4 ,in the petal 7fig4 #bd71 the walls are inflexed at tolerably regular distances1 so as to give rise to the appearance of a row of teeth lining the cell4 ,if the strip of petal be folded1 so as to exhibit the side view1 it will also be seen that the cells project outwards from the surface to form a bluntish point or papilla1 or the petals are papillose as it is called2 and the surface of the membrane around the papill is finely wrinkled1 so as to present the appearance of very delicate radiating lines or stri4 ,intermediate degrees of this inflexion may be found in various flowers1 between the slight condition seen in fig4 #ac and the extreme state of fig4 #bd1 as in the snapdragon 7,antirrhnum mjus74 ,anthers4--,the cavities of the anthers are lined with fibro-cellular tissue1 the fibres of which aid in discharging the pollen2 this may be seen by dissecting an anther of ,london pride 7,saxifraga umbrsa71 or of a wallflower 7,cheiranthus cheri7 in water4 ,it also exists in chickweed4 ,pollen4--,the pollen consists of minute grains called the pollen-granules4 ,they may be viewed either in the dry state as opake objects1 or when immersed in water as transparent objects4 ,as it is often difficult to moisten them1 they may be touched on the slide with a little spirit1 and then a drop of water added4 ,their forms are very varied and curious1 but they are difficult of observation from their minute size4 ,they consist of one or more coloured cells1 and these cells are remarkable for their surfaces exhibiting spines1 networks1 folds1 and markings of various kinds4 ,thus in the primrose the pollen-granules are cylindrical1 the surface being furrowed 7,pl4 ,i4 fig4 #af72 in the sunflower the granules are spherical1 and covered with tubercles surmounted by spines 7fig4 #ag72 in the garden convolvulus the surface of the spherical granules is covered with an elegant network1 in the meshes of which are also situated spines 7fig4 #ah72 and in the granules of chickweed the surface presents pits1 with minute tubercles in the centre 7figs4 #cj #ca74 ,the pollen-granules are often considerably altered by immersion in water2 so that1 in judging of their structure when examined in water1 the resulting alteration must be taken into account4 ,when ripe pollen-granules have been immersed in water for a short time1 one or more minute tubes will be seen protruding from their surface2 these are the pollen-tubes1 and the granular protoplasm contained in them is called the fovilla4 ,in the process of fertilization of the flower1 the pollen-granules fall upon the viscid stigma2 the pollen-tubes are then protruded1 and1 passing down the intercellular spaces of the style 7,pl4 ,i4 fig4 #ad71 enter an aperture in the ovule or young seed1 which is thus endowed with the power of growing into a new plant4 ,the pollen-tubes are often very long1 and they do not exist fully developed in the pollen-granules1 but grow down the style1 just as the little rootlet of a seed grows into the soil4 ,the style of a crocus will serve for dissecting out with mounted needles the long and very slender pollen-tube 7,pl4 ,i4 fig4 #ae74 ,ovary4--,the ovary by its growth and enlargement becomes the fruit4 ,there are many interesting microscopic structures to be found in fruits and the seeds they contain1 a few of which may be noticed here4 ,on examining the surface of the rind or pericarp 71 around1 1 fruit7 of an orange1 little dots will be seen1 paler than the rest of the surface4 ,these are receptacles of secretion1 or glands1 containing the evaporable or volatile oil upon which the fragrance of the orange depends4 ,they consist of loose cells1 surrounding a central cavity1 and are imbedded in the rind4 ,other receptacles of secretion1 called vitt 7vitta1 a band71 occur in the wall 7pericarp7 of the fruit of the ,umbellifer1 or ,parsley ,order of plants1 and their arrangement forms characters for distinguishing the genera4 ,they may be well seen in caraway-seeds2 for the caraway-plant is one of the ,umbellifer4 ,it must be observed that a caraway 8seed0 is not really a seed1 but consists of half the fruit2 for1 on careful examination1 one side of it will be found to be flattened1 the flattening resulting from the mutual pressure of the two half-fruits at that part2 moreover the dried style exists at its summit4 ,in the figure 7,pl4 ,i4 fig4 #ai71 the flattened part of the seed is next the observer4 ,the seed has five evident longitudinal ridges1 one at each corner or angle4 ,the vitt are dark-coloured 7fig4 #ai a71 and placed one between each pair of these ridges2 and they consist of long flattened spaces in the substance of the pericarp1 with transverse markings1 indicating internal cross partitions4 ,in botanical works1 the presence of five ridges1 with single vitt in the intervals1 is given as a character by which the half-fruits 7carpels7 of the caraway are to be distinguished4 ,but on closely inspecting the flattened surface1 another ridge is seen running down its middle2 so that the seed really has six ridges1 one of which is smaller than the rest from the pressure of the other half4 ,hence the character of five ridges with single vitt is incorrect4 ,the vitt contain the volatile oil to which the fragrance and pungency of the fruit is owing1 although some of the oil exists also in the cells of the kernel or albmen1 which forms the white and greater part of the seed4 ,the skin of a reddish apple1 peeled off in the manner described for petals1 exhibits beautifully the red colouring matter of different tints in adjacent cells1 while the pulp displays the cell-contents1 as already mentioned4 ,the latter may also be easily examined1 from their large size1 in most of the softer fruits1 as that of the snowberry or the cucumber4 ,as the ovary or fruit approaches maturity1 the petals and stamens wither and fall off1 the calyx often remaining1 and being sometimes adherent to the ovary1 at others free or unattached to it4 ,seeds4--,during the ripening of the fruit1 the seeds contained within it are gradually becoming further developed4 ,the seeds themselves are covered outside by a skin or coat called the testa 7testa1 a shell74 ,this is remarkable for frequently displaying various kinds of figured patterns1 consisting of raised networks1 ridges1 little knobs or tubercles1 c4 ,examples of these may be found in the seeds of the poppy 7,pl4 ,i4 fig4 #bg71 mignonette 7fig4 #bi71 and chickweed 7fig4 #ea74 ,some seeds are winged1 as it is called1 i4 e4 furnished with an extension of the testa beyond the margin of the seed4 ,this not unfrequently consists of aggregated fibre-cells1 the spiral fibre being very distinct1 as in the seeds of ,eccremocarpus scber 7,pl4 ,i4 fig4 #eb74 ,in the seeds of another curious plant in this respect1 viz4 ,collmia grandiflra1 the fibre-cells are separate1 so as to resemble hairs1 and very mucilaginous1 and in the dry seed are closely pressed to its surface4 ,if a portion of the testa of these seeds1 which can be procured at the seed-shops1 be cut off1 laid on a slide1 a cover applied1 and when the object is in focus1 a drop of water be added1 in a short time water softens the mucilaginous walls of the cells1 the power of the spiral fibres comes into play1 and the cells expand so as to form a very interesting object2 the cells1 in their expansion1 apparently writhing like so many minute worms 7,pl4 ,i4 fig4 #ce74 ,the seed itself1 which is contained within the testa or seed-coat1 consists essentially of the young plant or embryo4 ,this is composed of three parts1 viz4 the plmule 7plumula1 a little feather71 or the young stem2 the radicle 7radicula1 a little root71 or the young root2 and one or two1 rarely more1 imperfectly developed or rudimentary leaves1 the cotyledons 71 a cup74 ,these structures are closely packed in the seed1 and are not easily recognized at first4 ,by keeping seeds moist for a day or two until they begin to grow1 or germinate as the seed-growth is called1 they are readily detected1 and may then be more easily found in the dry seed4 ,when somewhat advanced in growth1 they are familiar to every one1 although they may not be recognized by their names4 ,in table 8mustard and cress10 the whole consists of these organs of the two plants2 the white stalk directed downwards being the radicle1 the two green leaf-like lobes the cotyledons1 and between the latter directed upwards is the very minute plumule1 which is more easily seen when the plants have been allowed to grow larger4 ,this structure of the seed is important to be known1 because the absence or presence and the number of cotyledons afford characters1 corresponding with those already mentioned in respect to the veins of the leaves and the structure of the stem1 for distinguishing the great divisions of the ,vegetable ,kingdom4 ,thus1 the ,exogens are ,dicotyledons 71 twice71 their seeds having two cotyledons2 while the ,endogens are ,monocotyledons 71 single71 having one only2 and the ,cryptogamic plants are ,acotyledons 71 without71 their seeds 7spores7 having none of these organs4 ,some seeds consist entirely of the embryo1 surrounded by the testa4 ,but in many others there is also present a usually whitish1 firm cellular substance1 called the albmen 7albumen1 white of egg74 ,the albumen of seeds often affords good specimens of secondary deposit1 the cells being almost entirely filled with it4 ,an example may be found in a section of vegetable ivory1 of which ornaments are sometimes made2 its structure resembles essentially that of the plum-stone4 ,in other instances the cells contain secreted matters1 as starch1 oil1 c42 and sometimes the cotyledons also contain starch and oil4 ,an example of the former exists in the albumen of wheat2 and of the latter1 in the horse-chestnut1 the filbert1 and mustard-seed4 ,the albumen and cotyledons serve to supply the embryo with nutriment until the roots have grown sufficiently to enable them to absorb it from the soil2 the cotyledons also serve as temporary leaves4 ,the form and relative position of the radicle and cotyledons serve to distinguish certain groups of plants4 ,this may be illustrated by the natural order ,crucifer1 or that containing the mustard1 wall-flower1 c4 ,thus1 in one group1 which may be represented by the wall-flower1 the cotyledons are flat or plane 7,pl4 ,i4 figs4 #dc #dd71 the radicle being applied to their edges4 ,this is best seen in a transverse section 7fig4 #dc74 ,they are then called accumbent 7accumbo1 to lie against72 and the botanical sign is ,o4 ,in the second group1 the cotyledons are plane 7,pl4 ,i4 fig4 #ch71 with the radicle applied to the back of one of them1 as in the seed of the common shepherd's purse 7,capsella bursa pastris7 7,pl4 ,,vii4 fig4 #ai74 ,they are then termed incumbent 7incumbo1 to lie upon71 and the sign is ,o4 ,while in the third group the cotyledons are folded in the middle1 like the leaves of a book 7,pl4 ,i4 figs4 #di #ej71 and the radicle is enclosed between them1 as in the white mustard 7,sinapis alba74 ,the cotyledons are then called conduplicate 7conduplico1 to fold72 and their sign is ,o 4 ,the plants above-mentioned are evidently all ,dicotyledonous1 or their seeds have two cotyledons2 and they contain no albumen4 ,in the ,monocotyledonous division1 which may be represented by a grain of wheat 7,pl4 ,i4 fig4 #ec71 the single cotyledon forms a minute sheath 7a71 enclosing the plumule 7b71 the radicle 7c7 being here but little developed at first1 the greater part of the grain consisting of the albumen 7d72 the grain should be softened in water before examination4 ,in the germinated grain the cotyledon appears as a pale sheath1 surrounding the convolute green leaves of the plumule2 which may be best seen in a transverse section 7,pl4 ,i4 fig4 #dh74 ,fertilization4--,a few words must now be said regarding the formation of seeds1 and the action of the pollen-tubes in the process of fertilization4 ,in the earliest stages of growth1 the young seeds1 or ovules as they are called1 appear as little buds1 arising from the inner wall of the ovary2 and the part from which they arise is called the placenta 7placenta1 a cake74 ,in chickweed 7,pl4 ,i4 fig4 #da c71 the placenta forms a central column2 and when the ovules are a little older1 they are found to have separated somewhat from the placenta1 but retaining a connexion by means of a little cord or stalk1 termed the funiculus 7funis1 a cord74 ,the ovules may be readily found in the ovary or young pod of a wall-flower1 the placentas forming four lines1 running longitudinally down the interior of the pod4 ,in this early condition the ovule consists of a mass of cellular tissue2 and as new formations are soon added to it1 it is termed in this state the ncleus4 ,around the nucleus are then formed two coats1 an outer1 called the prmine1 and an inner1 termed the secundine4 ,these coats or membranes are open at one end1 so as to leave a passage down to the apex of the nucleus2 the opening is called the formen4 ,these structures are well seen in the ovule of the wall-flower 7,pl4 ,i4 fig4 #ed71 the foramen in the figure being indicated by a 992 it will be noticed also that the funiculus runs down one side of the ovule1 so as to terminate at the bottom or base of the nucleus4 ,in ripe seeds1 the spot at which the funiculus has been attached is mostly perceptible in the form of a scar4 ,the slight prominence of the foramen can also often be distinguished1 as in the seed of chickweed 7,pl4 ,i4 fig4 #ea9972 in the ripe seed the foramen is termed the mcropyle1 and towards it the radicle of the embryo is always directed4 ,one of the cells of the nucleus near its apex then enlarges1 so as to form a sac1 called the embryo-sac4 ,this is excessively thin and transparent 7,pl4 ,i4 figs4 #de b #dg72 and in it1 also at the end next the foramen1 one or more 7in the chickweed one7 smaller cells are formed from the cell-contents of the embryo-sac1 which are called the embryonal vesicles 7,pl4 ,i4 fig4 #de a74 ,thus far developed1 the embryo exists prior to the expansion of the flower and the discharge of the pollen4 ,the embryo-sac is not figured in this early condition1 the embryonal vesicle being then smaller than that in fig4 #de b1 although occupying the same position4 ,when the pollen has escaped from the anthers and fallen upon the stigma1 the pollen-tubes growing down the intercellular passages of the style1 enter the foramen of the ovule1 and so reach the apex of the nucleus1 at which the embryonal vesicle contained in the embryo-sac is situated4 ,the end of the pollen-tube then adheres to the embryonal vesicle1 and such interchange of cell-contents takes place between them as effects fertilization4 ,the process of cell-formation in the fertilized embryonal vesicle then takes place rapidly1 new cells being formed by the division of its cell-contents 7,pl4 ,i4 fig4 #de a72 and it will be noticed that the new cells are formed at the end of the embryonal vesicle1 opposite to that situated at the apex of the embryo-sac4 ,as the cell-division and formation proceed further1 a mass of new cells is produced 7,pl4 ,i4 figs4 #df c #dg71 forming the rudimentary embryo2 and from this1 by further growth1 the perfected embryo 7fig4 #ee7 results2 or1 to use a fashionable technical term1 the simply cellular embryonic mass becomes differentiated into the radicle1 cotyledons1 and plumule1 forming the embryo4 ,it will be remarked that the position of the embryo in fig4 #ee is the reverse of that in figs4 #df #dg1 the radicle in the former being directed downwards1 whilst that of the embryo in the figure of the embryo-sac 7fig4 #dg7 is directed upwards4 ,the embryonal structures are very difficult of detection2 but it happens that in our little chickweed they are more easily dissected out than in most other plants4 ,for this purpose1 the ovules1 placed on a slide and lying in water1 should be picked to pieces with the mounted needles1 under the simple microscope4 ,they may be preserved in chloride of calcium or glycerine4 ,a clear distinction must be drawn between seeds1 which result from the process of fertilization1 and buds1 which are formed independently of this process4 ,both consist essentially of embryo plants2 but while the former originate from a single cell1 the latter are outgrowths of a parent stem1 from which their tissues are derived2 and while the former propagate the species1 the latter increase the individual4 ,the obvious use of seeds is the distribution of the species by the formation of new individuals4 ,in the general outline which has been given of the elements1 tissues1 and organs of plants1 they have been examined principally as existing in the higher groups1 or those of more complex structure2 and to enter further upon a description of these plants would involve the consideration of variations in the form and arrangement of the organs of which they are composed4 ,as these can mostly be investigated without the use of the microscope1 we must pass to those in which the entire plant consists of little more than simple or parenchymatous cells1 and in which the representatives of the flower are so inconspicuous1 or are reduced to so elementary a condition1 that the plants included in the ,division have been termed ,cryptogamic 71 concealed1 1 union--figuratively for reproductive organs7 or ,flowerless ,plants4 ,the reproductive organs of the ,cryptogamia are usually termed the fructification1 implying that they produce fruit1 but not flowers4 ,,plate ,,ii4 ,,page #di4 ,,ferns ,,and ,,lichens4 ,fig4 #a4 ,chlorococcum vulgare4 #b4 ,parmelia parietina4 #c4 ,parmelia parietina1 section of a saucer 7apothecium74 #d4 ,parmelia parietina1 gonidia and asci4 #e4 ,parmelia parietina1 asci and paraphyses2 #e a1 spores4 #f4 ,calicium clavellum4 #g4 ,calicium clavellum1 stalked apothecia4 #h4 ,calicium clavellum1 apothecium4 #i4 ,polypodium vulgare1 frond4 #aj4 ,polypodium vulgare1 lobe of frond4 #aa4 ,polypodium vulgare1 group of capsules 7thec74 #ab4 ,polypodium vulgare1 capsule and spores4 #ac4 ,polypodium vulgare1 spore germinating4 #ad4 ,polypodium vulgare1 prothallium4 #ae4 ,polypodium vulgare1 portion of prothallium1 with archegonia4 #af4 ,aspidium filix mas1 frond4 #ag4 ,aspidium filix mas1 pinnules with sori4 #ah4 ,aspidium filix mas1 single pinnule4 #ai4 ,scolopendrium vulgare1 frond4 #bj4 ,scolopendrium vulgare1 portion of frond4 #ba4 ,cladonia coccifera4 #bb4 ,cladonia cornuta4 #bc4 ,cladonia pyxidata4 #bd4 ,cladonia rangiferina4 #be4 ,cladonia rangiferina1 ends of podetium4 #bf4 ,graphis scripta4 #bg4 ,graphis scripta1 lirell4 #bh4 ,graphis scripta1 asci and spores4 #bi4 ,graphis scripta1 spore4 #cj4 ,opegrapha betulina4 #ca4 ,opegrapha betulina1 lirell4 #cb4 ,opegrapha betulina1 lirella4 #cc4 ,opegrapha betulina1 ascus with spores4 #cd4 ,scalariform ducts of ,brake 7,pteris74 ,illustration3 ,plate ,,ii4 ,w ,bagg sculp ,london3 ,john ,van ,voorst4 ,,chapter ,v4 ,,ferns1 ,,or ,,fil,,ices4 ,the general appearance of plants belonging to the class of ,ferns is so well known that it need scarcely be described1 especially since the introduction of the glass plant-cases1 by means of which the air can be kept so damp that ferns are now grown in the very heart of our cities4 ,their bright green and finely cleft leaves 7,,pi4 ,,ii4 figs4 #i #af7 or fronds 7frons1 a leaf7 as the leaf-like organs of the lower plants are called1 arising in tufts from the stems1 give them the elegant appearance we are called upon to admire1 whenever they are met with4 ,the brownish spots or stripes seen upon the back or under surface of the fronds1 and consisting of the fructification1 form also a simple character by which they may generally be distinguished2 although in a few of them the fructification is placed upon a distinct stalk4 ,the stem or rhizome 71 a root7 of a fern is mostly situated just beneath or at the surface of the ground1 and is commonly mistaken for the real root1 which is buried in the earth4 ,it is brownish outside1 and covered with scurfy scales or ramenta 7ramentum1 a shaving74 ,these scales are interesting microscopic objects1 from the distinctness with which they exhibit the cellular network4 ,a section of the rhizome exhibits the fibro-vascular tissue arranged differently from that in the stems of either ,exogens or ,endogens4 ,it forms curiously curved longitudinal plates1 a very abundant component of which is the scalariform 7scala1 a ladder7 duct 7,pl4 ,,ii4 fig4 #cd74 ,the walls of the scalariform ducts are angular1 and the secondary deposit is arranged in the form of transverse bars1 somewhat resembling the steps of a ladder2 which structure is best seen in a transverse or slightly oblique section4 ,the fronds are usually cleft nearly down to the main vein or midrib 7fig4 #i71 or pinnatifd 7pinna1 a feather1 findo1 to cleave72 sometimes the segments are similarly cleft1 so that the fronds are bipinnatifid4 ,the manner in which the veins usually branch is also peculiar1 each branch separating from the point of division at an acute angle with the original direction of the vein 7fig4 #bj71 so as to be forked4 ,it is also worthy of notice1 that the young frond is rolled up into a flat spiral1 or is circinate 7circino1 to go round71 before it opens4 ,we will now examine one or two species more minutely4 ,,polypodiace4 ,polypdium vulgare 7,pl4 ,,ii4 fig4 #i1 one-third of the natural size71 a member of this family1 is very common on old trunks of trees1 on banks1 c4 ,the frond is deeply pinnatifid1 the segments being oblong1 blunt 7obtuse71 scalloped 7crenate7 at the edges 7,,pi4 ,,ii4 fig4 #aj71 and becoming gradually shorter towards the apex of the frond4 ,on the back of the fronds are the little orange-coloured groups of capsules 7,pl4 ,,ii4 figs4 #i #aj72 these are called sori 71 a heap74 ,the capsules or thc 71 a case71 a magnified group of which is represented in fig4 #aa1 consist each of an aggregation of cells1 fixed to a stalk 7fig4 #ab72 and along the back of the capsule is a close row of thicker cells1 forming an elastic ring1 the annulus4 ,when the seed-like bodies or spores 71 a seed7 are ripe1 the annulus becomes straightened from its elastic power1 and tears the capsule open1 so that the spores are set free and scattered4 ,aspidium filix mas 7,pl4 ,,ii4 fig4 #af1 reduced to one third or fourth of the natural size71 is the most common ,british fern4 ,in this the fronds are pinnate1 i4 e4 the segments 7pinn7 corresponding to those of ,polypodium are cleft entirely to the main stalk1 the pinn 7fig4 #ag7 being pinnatifid2 and the segments of the pinn or the pinnules 7fig4 #ah7 are oblong1 obtuse1 and saw-edged 7serrate74 ,in all botanical works the fronds are incorrectly said to be bipinnate4 ,the sori are brown1 kidney-shaped 7fig4 #ah71 and differ from those of ,polypodium in being covered by a thin membrane 7indsium71 which is fixed to the frond at the notch4 ,scolopendrium vulgre 7,pl4 ,,ii4 fig4 #ai71 the ,hart's-tongue ,fern1 is common in hedges and on moist banks4 ,its fronds are simple or undivided1 strap-shaped1 heart-shaped at the base1 and narrowed to a point at the apex4 ,the sori 7fig4 #bj7 are brown1 narrow1 longish 7linear71 and transverse or slightly oblique4 ,the indusium is cleft down the middle1 so as to form a longitudinal fissure or suture4 ,reproduction4--,the spores of the ferns 7,pl4 ,,ii4 fig4 #ab a7 resemble in appearance the seeds of flowering plants on a small scale4 ,they are usually brown1 covered on the surface with little tubercles or other markings1 and when kept on a slide in a moist atmosphere1 as over a saucer of water covered with a bell-glass1 they germinate4 ,when this takes place1 one or more short1 brownish1 hair-like radicles emerge from one part of the surface 7,pl4 ,,ii4 fig4 #ac71 and a process containing chlorophyll issues from an adjacent spot4 ,as growth proceeds1 the latter by cell-division gives rise to a flattened two-lobed leafy cotyledon-like body or prothallium 71 before1 1 leaf71 with numerous rootlets springing from the base of the lobes4 ,the prothallium is of a peculiar dull-green colour1 different from that of the young frond which is subsequently formed4 ,this arises from the absence of stomata and intercellular passages containing air2 for the air in these passages of leaves and petals contributes greatly to the production of the brightness of their colours4 ,moreover1 the cells of the prothallium resemble those of the parenchyma of a leaf1 the epidermis with its wavy-margined cells being absent4 ,when the prothallium has attained its full development1 minute scattered protrusions from its cells occur on the margin or under surface1 resembling short and blunt hairs2 and each of these becomes partitioned off to form a new cell1 within which a number of crowded smaller cells are produced4 ,these organs are called antheridia 7anther1 and 1 resemblance72 and within each of the crowded smaller cells is contained a very minute1 colourless1 coiled fibre1 furnished with still finer filaments1 called cilia 7cilium1 an eyelash72 the ciliated fibres being termed spermatozoa 71 seed1 1 animal74 ,at a later period1 other organs are found also on the back of the prothallium4 ,these are larger than the antheridia1 and are composed of several cells1 arranged around a central canal which leads to an embryo-cell situated at its base 7,pl4 ,,ii4 fig4 #b74 ,these organs are the archegnia 71 beginning1 1 offspring74 ,when the antheridia are ripe1 they discharge the spermatozoa1 which are enabled to swim about by means of their cilia in water 7rain71 and entering the canal1 reach the embryo-cell1 which thus becomes fertilized4 ,when fertilized1 the embryo-cells produce the little fronds which afterwards grow into the mature plants4 ,hence the spores of ferns differ strikingly from the seeds of the higher plants in not containing the embryo radicle and cotyledons already formed1 these being produced during or after germination2 also in the fertilizing organs1 viz4 the antheridia or representatives of the anthers1 and the archegonia or the representatives of the pistils1 being produced from the cells of the prothallium4 ,the more minute of these structures are too difficult of observation and preparation for any one unaccustomed to microscopic manipulation1 so that they have not been figured in detail2 the figures given will1 however1 serve to guide the observer in their recognition4 ,preservation4--,the ferns may be easily preserved in the entire state1 by laying them flat between sheets of coarse unsized paper1 and subjecting them to moderate pressure in a screw-press2 the paper should be changed1 or dried before a fire every two or three days1 and the pressure repeated until the specimens become dry and rigid4 ,they may then be mounted on sheets of paper1 being fastened either with thread passed round the stalk or portions of the frond with a needle1 and tied in a knot behind1 or with strips of paper gummed at the ends4 ,the minute structures may be preserved either in the dry state or in glycerine4 ,,chapter ,,vi4 ,,mosses1 ,,or ,,mus,,ci 7,,muscus1 ,,moss74 ,i need scarcely refer to the figures in ,pl4 ,,iii4 to enable the reader to recognize the ,mosses2 every one knows them at once by their remarkably uniform general appearance1 their miniature-plantlike form1 their crowded little leaves1 concealing the slender wiry stems1 their growth in patches1 and their curious urn-shaped fruits raised up on slender bristle-like stalks4 ,the leaves of the mosses are simple1 i4 e4 not cut into segments1 and consist of one or two layers of cells4 ,the thinness of the leaves enables these cells to be seen very distinctly1 the closely united cell-walls giving the leaves a netted or reticulated appearance 7fig4 #dh71 and the grains of chlorophyll being generally few and readily distinguished4 ,the veins of the leaves1 or the nerves as they are usually called1 scarcely deserve the name2 for neither they nor even the stems contain fibro-vascular tissue1 but consist simply of elongate closely packed cells1 and often the leaves have no nerves4 ,the fruit of the mosses consists of a capsule1 sometimes called a sporangium 71 seed1 1 vessel71 usually placed at the end of a slender stalk1 called the sta 7seta1 a bristle72 but sometimes the stalk is absent or extremely short1 when the capsule is said to be sessile 7sessilis1 sitting74 ,the young capsule is covered with a thin extinguisher-like cap or calyptra 71 a cover71 which is carried up as the capsule and its stalk grow1 so as to be either entirely thrown off1 or to remain covering a greater or less portion of the capsule1 when this attains maturity4 ,,plate ,,iii4 ,,page #ed4 ,,mosses4 ,fig4 #a4 ,sphagnum acutifolium1 expanded leaf4 #b4 ,sphagnum acutifolium1 cells of leaf4 #c4 ,spermatozoa of ,polytrichum piliferum4 #d4 ,sphagnum acutifolium4 #e4 ,sphagnum acutifolium1 capsule4 #f4 ,gymnostomum truncatulum4 #g4 ,gymnostomum truncatulum1 leaf4 #h4 ,gymnostomum truncatulum1 capsule and operculum4 #i4 ,gymnostomum truncatulum1 spore4 #aj4 ,dicranum heteromallum4 #aa4 ,dicranum heteromallum4 #ab4 ,dicranum heteromallum1 leaf4 #ac4 ,dicranum heteromallum1 operculum4 #ad4 ,dicranum heteromallum1 calyptra4 #ae4 ,dicranum heteromallum1 capsule2 #ae a1 peristome4 #af4 ,tortula muralis4 #ag4 ,tortula muralis1 leaf4 #ah4 ,tortula muralis1 capsule2 a1 tooth of peristome4 #ai4 ,tortula muralis1 operculum4 #bj4 ,tortula muralis1 calyptra4 #ba4 ,tortula muralis1 archegonia4 #bb4 ,polytrichum piliferum4 #bc4 ,polytrichum piliferum1 leaf4 #bd4 ,polytrichum piliferum1 calyptra4 #be4 ,polytrichum piliferum1 antheridial stems4 #bf4 ,polytrichum piliferum1 single head4 #bg4 ,polytrichum piliferum1 antheridia and paraphyses4 #bh4 ,funaria hygrometrica4 #bi4 ,funaria hygrometrica4 #cj4 ,funaria hygrometrica1 leaf4 #ca4 ,funaria hygrometrica1 capsule2 a1 operculum4 #cb4 ,funaria hygrometrica1 stalk-like body4 #cc4 ,funaria hygrometrica1 young archegone4 #cd4 ,funaria hygrometrica1 more advanced archegone4 #ce4 ,funaria hygrometrica1 section of young capsule4 #cf4 ,funaria hygrometrica1 calyptra4 #cg4 ,funaria hygrometrica1 antheridia4 #ch4 ,funaria hygrometrica1 spores4 #ci4 ,funaria hygrometrica1 annulus4 #dj4 ,funaria hygrometrica1 archegonia4 #da4 ,funaria hygrometrica1 antheridial head4 #db4 ,funaria hygrometrica1 peristome4 #dc4 ,hypnum rutabulum4 #dd4 ,hypnum rutabulum1 leaf4 #de4 ,hypnum rutabulum1 capsule4 #df4 ,hypnum rutabulum1 spores4 #dg4 ,hypnum rutabulum1 peristome4 #dh4 ,hypnum rutabulum1 cells of leaf4 #di4 ,bryum capillare4 ,illustration3 ,plate ,,iii4 ,w ,bagg sculp ,london3 ,john ,van ,voorst4 ,the calyptra is either simply mitre-shaped1 or mtriform 7,pl4 ,,iii4 fig4 #bd71 or it is half-cleft1 or dimidiate 7figs4 #ad1 #cf74 ,when the capsule is ripe1 the upper part usually separates at a circular horizontal line 7fig4 #h7 as a kind of lid1 which is called the operculum 7operculum1 a lid71 and thus the spores are enabled to escape4 ,the rim of the capsule1 from which the operculum has separated1 forms its mouth1 and this often exhibits a fringe of teeth 7figs4 #ae1 #ah1 #ca71 arranged in one or more rows2 sometimes the teeth are replaced by a membrane1 or1 again1 both teeth and a membrane may be present4 ,this mouth-fringe is the peristome 71 around1 1 mouth74 ,in many mosses1 an elastic row or ring of cells is situated between the mouth of the capsule and its operculum1 called the annulus 7figs4 #ah #ci72 this1 when the capsule is ripe1 aids in throwing off the operculum4 ,it is important to become acquainted with the structure and arrangement of these parts1 as they form characters by which the families and genera of mosses are distinguished4 ,the capsules of the mosses form very beautiful microscopic objects1 especially those furnished with a toothed peristome4 ,most of the mosses produce their fructification in the winter and spring4 ,the class of mosses is divided into two ,orders1 according to whether the fruit-stalk is terminal1 i4 e4 arises from the end of the stem or its branches1 or whether it is lateral1 arising from the side of the stem4 ,those with the fruit-stalk terminal1 or the end fruited 7,pl4 ,,iii4 fig4 #bb71 form the ,acrocarpi 71 summit1 1 fruit72 while those with the fruit-stalks lateral1 or the side-fruited mosses 7fig4 #dc71 constitute the ,pleurocarpi 71 side74 ,the new shoots or young branches of the stems of mosses are termed innovations4 ,we will now examine a few common mosses more in detail1 beginning with the ,,acrocarpi4 ,sphagnum acutiflium 7,pl4 ,,iii4 fig4 #d7 is found in pools or bogs1 growing at the margins so as to be partially immersed4 ,in this moss1 the upper branches are grouped into a head4 ,the leaves are crowded1 and overlapping or imbricate 7imbrex1 a tile7 on the elongate stems2 they are egg-shaped 7ovate7 on the main stems 7fig4 #a71 and narrower or ovate-lanceolate on the branches2 they are nerveless1 and finely toothed at the apex4 ,the capsule 7fig4 #e7 is roundish-ovate1 without a peristome1 and the operculum is flattened4 ,the grouped arrangement of the upper branches renders the species of ,sphagnum easily recognized4 ,the structure of the leaves is also very peculiar and characteristic 7fig4 #b74 ,the cells of which they consist are of two kinds1 one 7fig4 #b a7 being colourless1 elongate1 pointed1 and containing a spiral fibre2 the other consisting of shorter and narrower obtuse cells1 containing chlorophyll1 and situated between the former4 ,in many of the former kind of cells1 little round apertures exist on the under surface1 and minute animals may sometimes be found imprisoned in them4 ,another species of ,sphagnum1 ,s4 obtusifolium1 is common1 and greatly resembles the above1 but has shorter and thicker stems1 and rounded-ovate1 very concave1 and obtuse leaves4 ,gymnostomum truncatulum 7,pl4 ,,iii4 fig4 #f7 is a common little moss1 found on banks and in fields and gardens4 ,in this there is no peristome1 although1 in the young condition1 a membrane extends more or less over the interior of the mouth of the capsule4 ,the stem is slender1 rigid1 and simple1 or but little branched4 ,the calyptra is dimidiate2 the operculum is present 7fig4 #h71 and terminates above in an oblique beak1 or it is obliquely rostrate 7rostrum1 a beak7 as it is called4 ,the leaves are obovate 7fig4 #g7 or ovate with the broader part remote from the stem1 and narrowed at the apex1 where the nerve protrudes or is excurrent 7excurro1 to run out74 ,the spores 7fig4 #i7 are reddish brown and smooth4 ,dicrnum heteromallum 7,pl4 ,,iii4 figs4 #aj #aa7 is probably the first moss the reader will meet with on banks and heaths in the early spring2 and it will be sure to be noticed on account of the bright green colour of the patches and the beautiful orange-brown capsules4 ,in this moss the capsule is nodding 7cernuous7 7,pl4 ,,iii4 fig4 #ae71 and has a single peristome1 consisting of sixteen equidistant teeth1 each being deeply cut or cleft longitudinally 7fig4 #ae a71 so that there are thirty-two teeth altogether2 and these are marked with internal cross-bars1 or transverse ridges4 ,the calyptra is dimidiate 7fig4 #ad72 and the lid is furnished with a long oblique beak 7fig4 #ae b74 ,the leaves are crowded1 strongly nerved 7fig4 #ab71 lanceolate at the base1 and very narrow towards the apex1 which is toothed2 they are1 moreover1 curved1 and bent towards one side1 or scund4 ,tortula murlis 7,pl4 ,,iii4 fig4 #af7 may be found on the top of almost every wall and on waste ground4 ,in this moss the peristome is single 7fig4 #ah71 consisting of thirty-two spirally twisted teeth1 arranged in pairs4 ,they are narrow and slender1 and each is composed of two longitudinal portions 7fig4 #ah a71 one of which is pale yellow1 the other reddish brown1 like the capsule1 and both are fringed and covered with very minute papill4 ,the capsule 7fig4 #ah7 is oblong1 the ring or annulus remaining for some time4 ,the lid is conical 7fig4 #ai71 with a longish somewhat oblique beak1 and the calyptra is dimidiate 7fig4 #bj74 ,the stems are very short2 the leaves 7fig4 #ag7 are oblong1 obtuse2 the nerve strong1 and projecting as a colourless spirally striated bristle4 ,the bristles often give the patches of the moss a hoary appearance on wall-tops4 ,the margins of the leaves are folded back or recurved1 giving them a peculiar thickened appearance4 ,the largest of our mosses are contained in the next genus1 viz4 ,polytrichum1 some of them having the stems from #b to #d inches1 or even more1 in height2 they are common on heaths and in woods4 ,polytrichum piliferum 7,pl4 ,,iii4 fig4 #bb7 is very common on open dry heaths4 ,this moss has simple stems1 with the leaves crowded on the lower part of those which are fertile or fruit-bearing4 ,the fruit-stalk is terminal 7acrocarpous72 the capsule ovate1 #d-sided or quadrangular1 with a knob or struma 7strma1 a swelling7 at the base1 the lid having a short beak4 ,the calyptra 7fig4 #bd7 is half-cleft 7dimidiate7 and very hairy4 ,the peristome is single1 and consists of sixty-four teeth4 ,the leaves 7fig4 #bc7 are lanceolate1 nearly upright1 the margins folded inwards or inflexed2 and they end abruptly in a saw-edged or serrated hair-like point4 ,polytrichum commne1 which is also very common1 is larger than the last species1 and may easily be distinguished by the curved and serrate leaves1 which have no bristle-point4 ,in the early spring1 patches of both these mosses may be found1 in which the stems are terminated by little rosettes 7figs4 #be #bf72 these will be referred to presently4 ,keeping still to the end-fruited or ,acrocarpous mosses1 we have next to mention ,funaria hygrometrica 7,pl4 ,,iii4 figs4 #bh1 #bi71 which is readily distinguished from most other mosses by the pale apple-green colour which it possesses before the capsule ripens4 ,it is extremely common on walls and waste ground4 ,the capsule of this moss 7fig4 #ca7 differs from those of the preceding mosses in the peristome being double 7fig4 #db71 or composed of an outer and an inner row of teeth4 ,the outer row consists of sixteen oblique reddish teeth1 which are marked with transverse bars or trabecul 7trabecula1 a little beam71 and their points are connected by a net-like thin plate4 ,the inner row contains also sixteen teeth1 arising from the division of the membrane lining the capsule2 these are yellowish1 thin1 and placed opposite the outer teeth4 ,the capsule itself is pear-shaped or pyriform1 orange-red when ripe1 curved1 and with the mouth oblique4 ,the calyptra 7fig4 #cf7 is half-cleft1 and expanded as if blown out below4 ,the lid 7fig4 #ca a7 is convex and obtuse2 and the annulus 7fig4 #ci7 is large and easily separable4 ,the fruit-stalks are curved near the top4 ,the leaves 7fig4 #cj7 are ovate1 concave1 entire1 with a nerve reaching the apex1 which is acute and prolonged into a little point1 or apiculate4 ,the spores 7fig4 #ch7 are small and reddish brown4 ,the specific name 7hygrometrica7 of this moss expresses its hygrometric property2 for if either the recent and moist moss be dried or the dry moss wetted1 the fruit-stalk gradually twists in opposite directions in the two cases4 ,the last of the ,acrocarpous mosses which we shall notice1 ,bryum capillare 7,pl4 ,,iii4 fig4 #di71 is tolerably common on trunks of trees1 on the ground1 and sometimes on walls4 ,the capsule of this moss has a double peristome or mouth-fringe2 the outer consisting of sixteen reddish-brown1 equidistant1 transversely striped teeth2 the inner composed of sixteen thin keeled teeth1 more or less split down the middle1 and with two or three intermediate cilia4 ,the capsule is nodding1 smooth1 oblong1 pear-shaped1 slightly narrowed below the mouth2 the lid being somewhat convex1 and furnished with a short slender beak4 ,the calyptra is dimidiate4 ,the leaves 7fig4 #ej7 are obovate1 the nerve extending beyond the point1 rendering them bristle-pointed4 ,the seeds 7fig4 #di a7 are small and green4 ,this moss serves to illustrate a great difficulty1 which will often occur to the student1 in determining whether a moss is end-fruited or side-fruited4 ,for in this1 as in many other end-fruited mosses1 a little side-shoot or young branch 7innovation7 grows from the main stem immediately below the leaves surrounding the base of the fruit-stalk1 so that the fruit-stalk appears to arise from the side of the stem4 ,the only method of overcoming the difficulty is to examine carefully the comparative size and thickness of the stem and the shoot1 and to determine which is the weaker and so the newer4 ,the leaves surrounding the base of the fruit-stalk1 which are mostly somewhat different in structure from the stem-leaves1 are called the perichtial 71 around1 1 bristle7 leaves4 ,from among the side-fruited or ,pleurocarpous mosses we shall select one only1 ,hypnum rutabulum 7,pl4 ,,iii4 fig4 #dc71 which is common on the trunks of trees and on banks4 ,in this moss1 the nodding unequal curved capsule 7fig4 #de7 has a double peristome1 resembling that of ,bryum 7fig4 #dg74 ,the calyptra is half-cleft1 and the lid conical and shortly beaked4 ,the stem is reclining or procumbent1 and the pale green imbricated leaves 7fig4 #da7 are ovate and pointed1 faintly saw-edged1 the nerve becoming indistinct at about the middle4 ,it will be noticed that the cells of the leaf 7fig4 #dh7 have the prosenchymatous form1 or are elongate with pointed ends2 and that the fruit-stalk 7fig4 #de7 is rough with little grains4 ,fructification4--,the fruit-producing organs of the mosses are of two kinds1 comparable to those of the flowering plants1 but with their names changed1 as in the case of the ferns2 the representatives of the anther being called antheridia1 and those of the pistil archegonia4 ,the antheridia may be best examined in ,polytrichum piliferum or commune1 the patches of stems with red rosette-like heads 7figs4 #be1 #bf7 being readily found in the spring on open heaths4 ,the coloured leaves forming these heads differ in form from those of the stem1 being broader and very sharp-pointed1 and have received the distinctive name of perignial 71 around1 1 offspring7 leaves4 ,in the centre of these leaves1 which must be separated with mounted needles in a drop of water1 the antheridia 7fig4 #bg71 forming oblong cellular green sacs1 will be seen2 and intermingled with them will be found some slender pale filaments1 composed of mostly two rows of cells1 which are the paraphyses 71 a side growth74 ,if the antheridia are quite ripe1 they swell somewhat in the water1 and from the free or unattached end a very delicate1 colourless1 cellular mass gradually escapes4 ,if the antheridia are not quite ripe1 the mass must be liberated by dissection4 ,on carefully examining this mass under a high power1 it will be seen to consist of very delicate rounded cells 7fig4 #c a71 each containing a coiled filament1 revolving more or less rapidly4 ,after a time1 these filaments 7fig4 #c b7 escape1 so that they may be examined more minutely4 ,they are excessively delicate1 and are best seen when dried on the slide4 ,each consists of a very slender curved filament1 with a still finer filament1 or cilium1 arising from it on each side4 ,these are the spermatoza or spermatozids 71 seed1 1 animal1 1 resemblance74 ,in ,funria the antheridia 7fig4 #cg7 may also be found1 by careful examination1 in the little green heads terminating some of the stems 7fig4 #da1 of the natural size74 ,in this moss1 the paraphyses are inflated at the summit into little knobs1 or they are capitate 7fig4 #cg74 ,the pistil-like organs of mosses1 or the archegnia1 from which the capsule is formed1 must be looked for in the winter or early spring4 ,they occur in the parts of the stems from which the fruit-stalk subsequently arises1 and are surrounded by perichtial leaves1 so as to resemble in general aspect the antheridial heads4 ,they are readily found in ,tortula and ,funaria1 which are always at hand4 ,the archegonia 7,pl4 ,,iii4 fig4 #ba7 differ in form from the antheridia1 being flask-shaped1 with a neck and a dilated base4 ,the neck contains a slender canal1 and within the base is a special embryonal cell1 from which the capsule is subsequently formed4 ,the spermatozoa of the antheridia pass down the canals of the archegonia1 and fertilize the embryonal cells2 but one archegonium only comes to maturity in each head1 the others ceasing to grow1 and withering1 in which condition they are found at the base of the fruit-stalk when the capsule is fully formed4 ,the embryonal cell grows by subdivision1 so as to form a stalk-like body1 which as it rises extends the archegonium upwards until it splits across near the base4 ,thus the archegonium becomes split horizontally into two parts1 the upper and longer of which forms the calyptra1 whilst the lower remains as a very short tube or sheath 7vaginula7 surrounding the base of the fruit-stalk4 ,the cellular stalk-like body then swells at the summit1 the swollen portion gradually becoming developed into the capsule1 by resolving itself into an outer wall lined inside with a coat forming the outer row of teeth at the top1 and within this a thinner membrane or spore-sac1 the cleft upper margin of which forms the inner teeth2 and within this are contained the spores4 ,the mass of cells within the spore-sac remains1 forming a central column1 called the columella4 ,these stages of growth may be readily traced in ,funaria4 ,in ,plate ,,iii41 fig4 #dj represents two fertilized archegonia of the natural size1 surrounded by the perichtial leaves2 fig4 #cc is a still more advanced archegone4 ,in fig4 #cd the calyptra has separated from the vaginule1 and contains the stalk-like body1 which is represented alone in fig4 #cb1 the dark summit indicating the commencing formation of the capsule4 ,fig4 #ce represents the young capsule1 in which all the parts are more advanced in growth4 ,when the seeds of mosses germinate1 they produce at first a green ,conferva-like filament1 which branches at one end1 the cells containing green endochrome1 while brownish little roots are given off from the other end4 ,the young leafy buds or young stems arise from these confervoid filaments4 ,examination4--,in the examination of the mosses1 the capsules should be viewed as opake objects while fixed in the forceps2 and to discover the minute structure of the teeth of the peristome1 a capsule should be wetted with spirit1 then immersed in water1 slit up with fine scissors1 and spread out with the mounted needles1 so as to form a transparent object4 ,in this way1 the curious structure of the teeth becomes very distinct4 ,it must be noticed that1 in the mosses1 the antheridia and the archegonia usually occur in separate flower-like heads2 or the mosses are either moncious or dicious 7p4 #ch74 ,preservation4--,the mosses may be dried under pressure1 and preserved entire in the same manner as the ferns or the flowering plants4 ,if simply dried without pressure1 their structure can be readily made out at any future time1 by immersing them in water1 or by keeping them for a few hours in a moist atmosphere4 ,the minute structures of mosses may be mounted in solution of chloride of calcium1 or in glycerine2 they keep extremely well without closing the cells4 ,,chapter ,,vii4 ,,alg 7,,alga1 ,,sea-,,weed74 ,the plants belonging to the ,class ,alg grow in water1 either in that of the sea or in fresh water2 a few of them1 however1 being found on damp earth1 damp walls1 c4 ,the marine ,alg are commonly known as sea-weeds2 but the fresh-water ,alg generally receive but little popular notice1 forming1 as they do1 slimy masses or strata1 of a green or brownish1 sometimes red1 colour4 ,alg are of simple structure1 consisting entirely of cells2 in some these are single1 in others1 united end to end1 to form threads or filaments1 or grouped into a leaf-like expansion1 or collected few together into a little spherical group or a flat plate4 ,they possess none of the fibres1 vessels1 or ducts of the higher plants1 although some long and slender cells1 existing in the stalks of the fronds of the larger kinds1 bear considerable resemblance to woody fibre4 ,they exhibit no distinction of stem and leaf1 but consist of fronds representing the stem and leaf combined and undistinguishable4 ,and the term frond must be understood to signify the separate parts arising from the point of attachment when they are fixed2 and in the case of those which are unattached or free1 the entire plant is called a frond4 ,the ,alg are divided into three ,orders1 viz4 the ,fucoide or olive-coloured ,alg1 the ,floride or red1 and the ,confervoide or green ,alg4 ,,fucoid,e1 ,fucoid ,alg1 or ,melanospore 71 black or dark74 ,the plants composing this order form our largest sea-weeds1 and are found everywhere in the sea and on the sea-shore4 ,they are of an olive-green or olive-brown colour1 and usually become darker on drying4 ,,plate ,,iv4 ,,page #fd4 ,,marine ,,alg4 ,fig4 #a4 ,dasya coccinea1 piece of4 #b4 ,dasya coccinea1 portion with capsule 7ceramidium74 #c4 ,dasya coccinea1 portion of main filament4 #d4 ,dasya coccinea1 section of filament4 #e4 ,melobesia polymorpha4 #f4 ,melobesia polymorpha1 portion with capsules 7ceramidia74 #g4 ,jania rubens4 #h4 ,jania rubens4 #i4 ,lithocystis ,allmanni4 #aj4 ,ceramium nodosum4 #aa4 ,ceramium nodosum1 filament4 #ab4 ,ceramium rubrum1 filament4 #ac4 ,ceramium rubrum1 tetraspore4 #ad4 ,ceramium rubrum1 end of filament4 #ae4 ,ceramium rubrum1 capsule 7favella74 #af4 ,fucus vesiculosus1 receptacles of4 #ag4 ,fucus vesiculosus1 capsules 7conceptacles74 #ah4 ,fucus serratus1 antheridial conceptacles4 #ai4 ,spore of ,fucus vesiculosus4 #bj4 ,antheridia of ,fucus serratus4 #ba4 ,plocamium coccineum1 sporophyll4 #bb4 ,plocamium coccineum1 with capsule 7coccidium74 #bc4 ,plocamium coccineum1 portion of frond4 #bd4 ,plocamium coccineum1 tetraspore from sporophyll4 #be4 ,polysiphonia fastigiata1 portion of4 #bf4 ,polysiphonia fastigiata1 filament with capsules 7ceramidia74 #bg4 ,polysiphonia fastigiata1 portion of filament4 #bh4 ,corallina officinalis4 #bi4 ,corallina officinalis1 portion of filament4 #cj4 ,corallina officinalis1 capsule 7ceramidium74 #ca4 ,enteromorpha compressa4 #cb4 ,enteromorpha compressa1 cells of frond4 #cc4 ,hypnea purpurascens1 capsule 7coccidium74 #cd4 ,hypnea purpurascens1 spores4 #ce4 ,hypnea purpurascens1 filament4 ,illustration3 ,plate ,,iv4 ,w ,bagg sculp ,london3 ,john ,van ,voorst4 ,fcus vesiculsus1 with its parallel-sided or linear olive-brown fronds1 is known to every one as the seaweed which is hung up to act as a weather-glass4 ,the fronds have a central stout vein1 or midrib1 and scattered air-bladders1 mostly in pairs4 ,the fructification consists of yellowish oval enlargements of the ends of the fronds1 called the receptacles 7fig4 #af72 but these are somewhat variable in form1 being often angular or truncate4 ,on holding one of the receptacles to the light1 it will appear to contain a number of little grains imbedded in its substance1 slightly projecting above the surface1 and in the centre of each is a minute dot or pore4 ,these grains are the capsules1 or conceptacles1 and contain the spores4 ,the substance of the receptacles is composed of a beautiful network of colourless1 jointed1 cellular fibres 7figs4 #ag a and #ah a71 the meshes of which are filled with a transparent gelatinous substance2 but immediately around the conceptacles the cells are shorter and more closely packed4 ,the spores 7fig4 #ai7 are arranged in the conceptacles in a radiate manner2 they are brown1 and surrounded by a colourless sac1 called the perispore 71 around1 1 seed72 and between them are numerous slender1 colourless1 jointed filaments1 the paraphyses4 ,the spores are not1 however1 truly single spores1 for they ultimately divide into eight segments or sporules1 each of which is capable of producing a new plant4 ,in the conceptacles of some fronds of ,fucus no spores will be found1 the conceptacles 7fig4 #ah7 being filled with elegantly branched colourless filaments 7fig4 #bj71 the ends of many of them being distended into little yellowish sacs2 these are the antheridia4 ,the antheridia contain large numbers of exceedingly minute spermatozoa1 furnished with two cilia1 and very similar to those existing in the antheridia of the mosses2 these1 escaping through the pore of the conceptacle1 fertilize the spores4 ,the figure 7#bj7 in the plate was drawn from a conceptacle of ,fucus serrtus1 another common species1 differing from ,f4 vesiculosus in having the margins of the frond serrate2 the antheridia of the two species do not1 however1 differ in any important respect4 ,to examine the conceptacles of ,fucus and their contents1 the receptacles should be soaked in water1 if not fresh1 and thin sections made with a sharp knife4 ,they form very beautiful objects1 and may be preserved in chloride of calcium or glycerine4 ,,florid,e1 or ,rhodosperme 71 rose1 1 seed74--,the second ,order of ,alg1 forming the ,floride 7flos1 a flower71 comprises the red sea-weeds2 a few of them are purple1 or greenish-red2 so that by the colour alone they may be readily distinguished from the ,fucoids1 and from nearly all those of the next ,order1 the ,confervoids4 ,a few of them are leaflike1 or possess flat fronds2 but most of them consist of finely divided or feathery fronds4 ,they are often found upon the sea-shore of a dirty white colour1 the colouring matter having been decomposed or washed out by rain4 ,we shall consider a few of the genera and species under the heads of the families to which they belong4 ,,corallina,,ce1 the ,corallines1 or calcareous ,alg4--,in this family we have the beautiful ,corallna officinlis 7,pl4 ,,iv4 fig4 #bh71 the common ,coralline1 which is very abundant on the sea-shore1 attached to larger sea-weeds1 shells1 and rocks4 ,it is hard and chalky1 from the presence of a large proportion of carbonate of lime in its minute cells4 ,the fronds are composed of jointed and branched filaments4 ,the fructification 7figs4 #bi and #cj7 consists of ovate cellular capsules1 or ceramidia 71 earthen vessel71 placed mostly at the ends of pinnate stalks1 and containing a tuft of somewhat club-shaped jointed spores1 springing from the base of the capsules 7fig4 #cj74 ,when ripe1 the spores escape from a pore or hole in the end of the capsules4 ,the spores are #d-;jointed1 and hence are called tetraspores 71 four74 ,to observe these spores1 the capsules must be soaked in strong vinegar for some hours1 and then washed with water1 to dissolve the calcareous matter4 ,jnia rbens 7,pl4 ,,iv4 figs4 #g and #h7 is another common and very elegant little coralline1 and is of a pale red colour4 ,it differs from the last in the branches being dichotomous 71 in two1 1 cutting7 or forked1 instead of pinnate4 ,the capsules1 or ceramidia1 have also two short horn-like branchlets1 placed one on each side1 near the end4 ,the genus ,melobsia has the frond crustaceous1 i4 e4 forming a hard crust or layer4 ,m4 polymorpha 7,pl4 ,,iv4 figs4 #e and #f7 is common on shells1 stones1 c4 ,the capsules 7ceramidia7 here form little blunt cones1 scattered over the crusts1 and containing the tufted tetraspores1 as in ,corallina4 ,lithocystis ,allmanni 7fig4 #i7 is very minute1 and not uncommon upon sea-weeds1 stones1 c4 ,it consists of a single fan-shaped crustaceous layer of cells1 closely investing the body to which it is attached2 its fructification is unknown4 ,leaving the family of crustaceous ,floride1 we shall now pass to those of softer consistence1 although all the marine ,alg contain a considerable quantity of calcareous matter4 ,,rhodomela,,ce4--,in this family we have the large genus ,polysiphnia1 in which the frond 7,pl4 ,,iv4 figs4 #be and #bf7 is filamentous1 the filaments being apparently jointed and longitudinally striated4 ,the filaments are composed of rings of cells 7fig4 #bg71 arranged end to end1 and containing dark endochrome4 ,the ends of the colourless cell-walls separating the endochromes of the cells of adjacent rings produce the jointed appearance2 while the striated appearance is caused by the dark cells being elongate and the cell-walls thick1 so as to form white interspaces4 ,the fructification consists of capsules 7ceramidia71 attached to the sides of the branches1 containing pear-shaped spores1 with tetraspores imbedded in swollen branches of separate plants4 ,polysiphnia fastigita 7fig4 #be1 a small piece7 is common1 attached to the fronds of ,fucus4 ,its filaments are rigid1 bristle-like1 of the same breadth throughout1 forked1 and forming globular brown or yellowish tufts1 from #b to #d inches long4 ,the joints are broader than long1 each with #af-ah of the dark cells4 ,in the centre of the branches of this sea-weed is a row of curious objects 7fig4 #bf a71 consisting of a dark-coloured body surrounded with irregular spiny marginal processes1 and with a colourless short process above and below4 ,these require further investigation4 ,p4 nigrescens is also common among masses of seaweeds4 ,its filaments are brown1 pinnate1 the branches awl-shaped1 and the joints about as long as broad4 ,dsya coccinea 7,pl4 ,,iv4 figs4 #a and #b1 representing small portions of a filament7 is a very common filamentous red sea-weed of the same family4 ,the filaments are #f-h inches long1 and bipinnate1--the larger ones somewhat resembling those of ,polysiphonia1 in being composed of parallel longitudinal cells1 arranged round the centre1 but containing also smaller intermediate cells2 while the smallest branches 7fig4 #b71 which arise in tufts1 consist of a single row of cells1 little longer than broad4 ,the fruit consists of ovate capsules 7ceramidia71 placed at the base of the branches1 and containing a round mass of spores4 ,there is also another kind of fructification1 occurring on distinct plants2 this is formed of one or two rows of tetraspores1 immersed in pod-like capsules1 called stichidia 71 row74 ,,delesseria,,ce4--,in this family1 the typical or most highly developed genus of which1 ,delessria1 has beautiful leaf-like rose-red fronds1 we shall examine the common ,plocmium coccineum 7,pl4 ,,iv4 figs4 #bc and #bb74 ,this is of a fine red colour2 the fronds are from #b to #ab inches long1 and consist of numerous branched and bushy filaments4 ,these are compressed1 with the branchlets arranged in alternate rows on the two margins of the stem4 ,the end branchlets are acute and pectinate 7pecten1 a comb71 or arranged like the teeth of a comb4 ,the cells of which the filaments consist are small and angular1 giving the surface the appearance of being elegantly netted under a high power4 ,the fruit 7fig4 #bb7 consists of globular capsules1 called coccidia 71 a berry71 placed in the axils or forks at which two branches separate1 and containing a mass of angular spores4 ,there are also tetraspore-pods 7stichidia71 as in ,dasya2 and tetraspores 7fig4 #bd7 in little leaf-like altered branches 7fig4 #ba71 called sporophylles 71 seed1 1 leaf71 and antheridia are present4 ,,rhodymenia,,ce4--,in this family we have ,hypnea purpurascens 7,pl4 ,,iv4 fig4 #ce74 ,the filamentous pale purple frond of this sea-weed is from #f inches to a foot or more in length1 the branches being alternate and spreading4 ,the fructification consists of capsules or coccidia 7fig4 #cb71 immersed in the branches1 and containing the spores 7fig4 #cd74 ,tetraspores also occur in the cells of the surface of the filaments4 ,,ceramia,,ce4--,this is the last family to be noticed4 ,cermium nodsum 7,pl4 ,,iv4 figs4 #aj and #aa71 which belongs to it1 is a most delicate and elegant filamentous sea-weed1 commonly found attached to other sea-weeds4 ,the filaments are hair-like or capillary1 irregularly dichotomous2 they consist of colourless cells1 #c or #d times as long as broad1 and with thick walls4 ,the junctions of the cells are swollen 7fig4 #aa71 and covered with very minute dark red cells1 giving them a knotty and jointed appearance to the naked eye or under a low power4 ,the globular capsules1 or favel'l 7favus1 a honeycomb71 containing the numerous spores1 are situated at the ends of the branchlets1 and the tetraspores 7fig4 #aa7 in twos or threes on the outer margins of them4 ,in ,cermium rbrum1 which is also very common1 being found attached to stones1 rocks1 and the larger ,alg1 the filaments 7,pl4 ,,iv4 fig4 #ab7 are stouter than in ,c4 nodosum1 branched so as to form tufts from #b to #aj inches long1 and their ends forked1 with the tips hooked inwards 7fig4 #ad74 ,the central cells of the filaments are large and rounded1 and their walls are entirely covered with a layer of very small angular red cells4 ,the globular capsules 7fig4 #ae71 or favell1 are situated on the suter surface of the branches1 stalked1 and supported by #c or #d short branchlets4 ,the tetraspores 7fig4 #ac7 are imbedded in the branches1 towards the ends4 ,the capsules called favell differ from the coccidia in the walls being simply membranous1 while the walls of the coccidia1 like those of the ceramidia1 are composed of cells4 ,the tetraspores are usually imbedded1 among the cells of the superficial layer of the filaments1 and are not very easily recognized by an unpractised eye2 it will be observed in the figures that they are sometimes cleft horizontally1 at others obliquely4 ,,confervoid,e4--,this ,order consists principally of the green freshwater ,alg1 although some of them are yellowish brown1 purple1 or red1 and some are marine4 ,their general structure may be best illustrated by selecting certain common examples from the families composing the order4 ,the families are #ac in number4 ,the species which are figured in the plates are found in fresh water1 except when otherwise stated4 ,,plate ,v4 ,,page #gj4 ,,freshwater ,,alg4 ,fig4 #a4 ,conferva floccosa1 single filament4 #b4 ,lyngbya muralis1 single filament4 #c4 ,ulothrix mucosa 7871 filament4 #d4 ,synedra radians1 prepared frustules4 #e4 ,synedra radians1 tuft of natural frustules4 #f4 ,cladophora crispata1 with zoospores 7a74 #g4 ,batrachospermum moniliforme1 portion of filament4 #h4 ,batrachospermum moniliforme1 filament4 #i4 ,closterium acerosum4 #aj4 ,draparnaldia glomerata4 #aa4 ,spirogyra quinina4 #ab4 ,spirogyra nitida1 filaments conjugating4 #ac4 ,zygnema cruciata4 #ad4 ,coleochte scutata4 #ae4 ,xanthidia in flint4 #af4 ,micrasterias rotata4 #ag4 ,gomphonema acuminatum4 #ah4 ,gomphonema acuminatum1 prepared frustules4 #ai4 ,ankistrodesmus falcatus4 #bj4 ,pediastrum ,boryanum4 #ba4 ,hyalotheca dissiliens4 #bb4 ,pinnularia viridis4 #bc4 ,fragilaria capucina4 #bd4 ,fragilaria capucina1 prepared frustules2 s99 side view of ,f4 virescens4 #be4 ,scenedesmus quadricauda4 #bf4 ,schizogonium1 probably a form of ,lyngbya4 #bg4 ,campylodiscus costatus4 #bh4 ,nitzschia minutissima1 front view4 #bi4 ,nitzschia minutissima1 valves4 #cj4 ,epithemia turgida4 #ca4 ,diatoma elongatum1 natural frustules4 #cb4 ,diatoma elongatum1 prepared frustules4 #cc4 ,cocconeis placentula4 ,illustration3 ,plate ,v4 ,w ,bagg sculp ,london3 ,john ,van ,voorst4 ,,conferva,,ce4--,on removing some of the soft green matter found adhering to the stems of water-plants in any pool or pond1 one of the species of ,conferva1 ,c4 flocculosa1 is almost sure to be met with4 ,on close inspection with the naked eye1 the green filaments of which it consists are just visible1 as extremely fine1 soft1 silky threads2 and1 under a high power of the microscope1 the filaments are seen to be unbranched1 and composed of a single row of cells 7,pl4 ,v4 fig4 #a71 or joints1 as they are called in technical works2 these are #b or #c times as long as broad4 ,in some specimens the joints are swollen1 so as to present a rounded outline4 ,in another common species1 ,c4 bombycina1 the filaments are somewhat more slender1 and the joints are from #c to #e times as long as broad4 ,cladophora crispta4--,this ,confervoid forms large1 entangled1 dull-green masses1 composed of branched1 tufted1 somewhat rigid and coarse filaments4 ,it is often a troublesome overrunner of the fresh-water vivarium4 ,the filaments are composed of thick-walled cells 7,pl4 ,v4 fig4 #f71 from #d to #f times as long as broad1 and often containing minute starch-granules4 ,the ,confervace have two modes of reproduction4 ,the first of these consists in the division of the endochrome of the joints into a number of distinct segments1 each of which becomes furnished at one end with two very slender cilia 7,pl4 ,v4 fig4 #f a74 ,after a time1 these ciliated bodies1 which are called zoospores 71 animal1 1 seed7 or gonidia 71 seed1 1 resemblance71 escape from the cells either by their rupture or through a papillary orifice1 and swim about in the water1 ultimately losing their cilia and growing into cells resembling those of the parent plant4 ,in the second method1 which occurs1 for instance1 in ,conferva bombycina1 certain of the joints enlarge so as to become rounded or inflated2 their endochrome then becomes coated with a new cell-wall1 and so forms a spore1 which subsequently escapes from the cell and germinates4 ,,ch,,tophora,,ce4--,draparnaldia glomerta forms small green jelly-like masses1 adhering to sticks and stones in water4 ,these consist of branched filaments 7,pl4 ,v4 fig4 #aj71 prolonged at the ends into colourless hair-like points1 and composed of single rows of cells1 the green endochrome forming a band across the middle of each cell1 the ends being colourless4 ,in ,coleochte scutta 7,pl4 ,v4 fig4 #ad7 the cells are closely united1 so as to form a minute flat green disk4 ,in the natural state1 this beautiful little object adheres to the submerged leaves and stems of water-plants1 and is therefore difficult to be found4 ,but if a few healthy water-plants be kept for some time in a glass jar1 the little ,coleochte1 which is about as large as a pin's head1 will often be found adhering to the side of the glass4 ,,bat,,rachosper,,me4--,the members of this family resemble to the naked eye the little masses of ,draparnaldia1 and they are found in the same localities4 ,they are of various colours1 being green1 brown1 purple1 or red4 ,they consist1 as in ,batrachospermum moniliforme 7,pl4 ,v4 fig4 #h71 of branched filaments1 which have a knotty appearance under a low power4 ,the larger filaments are composed of cells arranged end to end1 the knots consisting of numerous smaller whorled filaments1 i4 e4 filaments arising from around them at the same level 7fig4 #g74 ,the cells composing the whorled filaments are beaded or moniliform1 and are prolonged into colourless hair-like points4 ,the globules seen among the branches 7fig4 #g7 consist of groups of spores4 ,,zygnema,,ce4--,the members of this family resemble the ,confervace in consisting of simple cellular filaments 7,pl4 ,v4 figs4 #aa1 #ac71 but differ from them in the elegant arrangement of the endochrome3 this forms beautiful spiral bands1 as in ,spirogyra quinina 7fig4 #aa71 or star-shaped masses1 as in ,zygnema cruciata 7fig4 #ac74 ,a remarkably curious phenomenon met with in them is the manner in which the spores are formed1 and which is known as conjugation4 ,in this process the opposite cells of two distinct filaments1 lying near together1 push out protrusions of the cell-walls1 which meet and open into each other1 forming cross tubes1 as in ,spirogyra nitida 7,pl4 ,v4 fig4 #ab74 ,the contents of the opposite cells of the filaments then unite1 forming large spores1 which remain either in the cells of one of the filaments or in the cross tubes4 ,the three species figured are common in clear pools4 ,,desmidia,,ce4--,the ,desmidiace are truly microscopic1 few of them being even perceptible to the naked eye without the very closest examination4 ,they are very beautiful1 on account of their bright green colour and often elegant forms4 ,many of them are very common1 existing in every pond or ditch2 but they abound most in clear open boggy pools on heaths4 ,on placing some water containing them in a glass jar and exposing it to the light1 they will often be found adhering to the glass1 or forming a layer on the surface of the muddy sediment4 ,the ,desmidiace consist mostly of single cells 7,pl4 ,v4 figs4 #i1 #af72 and these consist of two equal halves or segments1 as indicated either by a paleness of the endochrome or a deep constriction at the line of junction1 which is called the suture4 ,the cells are often elegantly lobed and cut1 or spiny2 and in many the surface exhibits minute markings1 consisting of little protrusions of the cell-wall outwards1 or inflations1 as they are called4 ,their reproduction is effected by division and conjugation4 ,in the process of division the cells gradually separate at the suture1 and a new half-cell is formed upon each old half1 which grows until it attains the size and form of the original half of the parent-cell4 ,the conjugation is effected by two cells approximating so that their sutures are near together1 the cells then open at the sutures1 and the effused contents become united to form a spore or sporange1 from which one or more individuals are formed4 ,these spores are often elegantly spinous on the surface4 ,among the species selected for illustration is ,clostrium acersum 7,pl4 ,v4 fig4 #i71 in which the cells are single1 elongate1 very slightly curved or lunate2 the endochrome forms long bands1 often containing numerous globules or transparent vesicles4 ,at each end of the cells is a round transparent vesicle1 containing exceedingly minute granules1 which exhibit a trembling kind of motion4 ,between the cell-wall and the cell-contents very fine currents may also be detected1 forming a circulation resembling that in the hairs of ,tradescantia4 ,in ,micrastrias rotta 7,pl4 ,v4 fig4 #af7 the cells1 which are single1 are deeply cleft into two segments at the suture1 the segments being again regularly cut into five lobes1 which are toothed or dentate4 ,in ,hyalothca dissiliens 7,pl4 ,v4 fig4 #ba7 the cells are united into a cylindrical filament1 and are surrounded by a very delicate gelatinous sheath4 ,in ,ankistrodesmus falctus 7,pl4 ,v4 fig4 #ai7 the cells resemble those of ,closterium in shape1 but are aggregated into faggot-like bundles1 and are very much smaller4 ,in the beautiful little ,pediastrum borynum 7,pl4 ,v4 fig4 #bj7 the cells are aggregated into a disk1 the marginal cells being bidentate or having each two points1 so that the whole resembles a star4 ,the species of ,pediastrum are reproduced by the contents of each cell subdividing into numerous ciliated segments or zoospores1 which subsequently escape in a mass from the cell1 ultimately losing their cilia1 and reuniting to form a new individual4 ,in ,scenedesmus quadricauda 7,pl4 ,v4 fig4 #be7 the oblong cells are united1 side by side1 the outermost cells being furnished with a bristle at each end4 ,the division of these cells takes place obliquely1 so that in the divided groups the cells are situated in two alternate rows4 ,the spores of many of the ,desmidiace are spinous1 and they are often found fossil in flint 7,pl4 ,v4 fig4 #ae74 ,to detect them in this substance1 thin slips of flint may be examined under a half-inch power2 or the chips of flint may be cemented to a slide with balsam1 and ground down on a hone4 ,the ,desmidiace must be mounted in the moist state3 the smaller ones will keep well in chloride of calcium2 but the larger ones are injured both by that liquid and by glycerine4 ,the remarks made upon mounting1 at page #ae1 are especially applicable to these delicate organisms4 ,,diatoma,,ce1 or ,siliceous ,alg4--,the members of this family are singly very minute2 but when existing in large numbers1 as they are often found at the bottom of ditches and ponds1 on the submerged stems of water-plants1 or upon damp ground1 they form yellowish-brown evident masses or strata4 ,they occur both in sea-and in fresh water4 ,they usually consist1 like the ,desmidiace1 of single cells1 which are called frustules4 ,but they are especially characterized by the cell-walls being imbued with silica or flint1 so that if the frustules be heated to redness upon the point of a knife or a slip of platinum-foil1 which destroys the organic part of the cells1 the coat of silica remains1 exhibiting the perfect form of the original cells or frustules4 ,the form of the frustules is very different in the various genera and species1 as represented in ,pl4 ,v4 figs4 #bb1 #bc1 #bg1 #cj1 #ca1 and ,pl4 ,,vi4 figs4 #af1 #ag1 #bc2 and it will be noticed that1 in the figures1 two views are given of each frustule1 f indicating the front view1 and s the side view4 ,in all the front views1 as in ,pl4 ,v4 fig4 #bb1 one or more lines will be observed running longitudinally down the middle of the frustules1 and corresponding to the indications of division existing in the cells of the ,desmidiace4 ,each half of a frustule is called a valve1 and the line at which these valves meet is called the suture4 ,that side or aspect of the frustule in which the suture lies 7fig4 #bb f7 is the front view2 and the other aspect of the frustule 7fig4 #bb s7 is the side view4 ,the frustules are mostly four-sided--the main breadths of the two opposite valves forming two sides1 and the bent margins of the valves1 with the back and front of the hoop1 forming the two other sides2 so that the view presented by the side of a frustule is the same as that of a single valve4 ,the suture is the line at which the division of the frustules takes place in the formation of new individuals4 ,in this process the cell-contents divide into two parts1 as in ordinary endogenous cell-formation1--the two new surfaces thus produced becoming coated with a new portion of cell-wall or valve1 so that two frustules now occupy the place of the original one4 ,at the same time a siliceous band1 encircling the frustules at the line of suture1 is formed to fill up the interval between the edges of the parent valves2 this is the hoop 7,pl4 ,v4 fig4 #bb f2 ,pl4 ,,vi4 fig4 #aj f71 and beneath it lie the two newly formed valves4 ,in many cases ,i believe that each half-frustule becomes coated with a new entire cell-wall1 with its siliceous valves4 ,the frustules of the ,diatomace are constantly undergoing division when in vigorous growth4 ,after the frustules have divided1 the new ones either separate entirely1 as is perhaps most commonly the case2 or they remain united1 sometimes completely1 so as to constitute a filament 7,pl4 ,v4 fig4 #bc71 while at others the frustules cohere only at the angles 7,pl ,,vi4 fig4 #bc71 so as to form a zigzag chain4 ,in some species1 the frustules are attached to foreign bodies by means of a gelatinous cushion 7,pl4 ,v4 fig4 #e2 ,pl4 ,,vi4 fig4 #g72 while in others they are situated upon a simple or branched gelatinous stalk 7,pl4 ,v4 fig4 #ag7 or stipes 7stipes1 a stem74 ,when the frustules are examined in the living state1 the cell-contents resemble those of ordinary vegetable cells1 excepting in regard to the colour1 and exhibit granules and globules1 and sometimes a nucleus is visible4 ,it will also be noticed that many of the free frustules move slowly across the field of the microscope2 but the cause of the motion is unknown4 ,when the frustules have been properly prepared1 the surface of the valves exhibits a number of coarser or finer markings1 consisting of dots1 lines 7stri71 flutings1 or networks1 c41 arranged with great regularity and symmetry1 often of extreme minuteness1 and rendering them exquisite objects under the microscope4 ,the exhibition of these markings requires not only that the valves shall be properly prepared and mounted1 but that the object-glasses be of good quality1 and that the management of the light be thoroughly understood2 so that to a beginner1 their examination is often a matter of great difficulty2 for only the very coarsest or largest of these markings can be perceived in the natural frustules4 ,the appearance of these markings1 and even their apparent absence or presence1 frequently depends upon the kind of illumination used3 thus1 under one kind of illumination the valves may appear simply white or coloured1 while under another they appear covered with lines1 and under a third with dots4 ,it will often be observed1 also1 that the colour of the valves varies according to the illumination and the power used--the same valve appearing white1 yellow1 brown1 blue1 c42 and the wet or dry state of the frustules often cause a decided difference in their appearance as regards colour4 ,to illustrate the forms and markings of the frustules and valves1 we may select the following species taking first those which occur in fresh water4 ,in ,epithmia turgida 7,pl4 ,v4 fig4 #cj71 the side-view or valve 7s7 exhibits transverse or slightly radiating lines1 with intermediate rows of dots--these markings being continued over the margins of the valves so as to appear also in the front view 7fig4 #cj f71 ceasing at the hoop4 ,the frustules are curved or arcuate 7arcus1 a bow7 in the side view1 oblong and narrowed at the ends in the front view4 ,in ,fragilria capucna 7,pl4 ,v4 fig4 #bc71 which is extremely common in fresh-water pools1 c41 the frustules are united side by side into long filaments1 which are often twisted4 ,in the separate and prepared frustule1 the front view 7,pl4 ,v4 fig4 #bd f7 is rectangular1 the valves 7s7 being narrowly lance-shaped or lanceolate4 ,the valves under ordinary illumination appear colourless and without markings1 but1 by proper management of the light1 very fine transverse stri are seen upon them1 consisting of rows of very minute dots4 ,fig4 #bd s99 represents the valve of ,fragilaria virescens1 a nearly allied species4 ,diatoma elongtum 7,pl4 ,v4 fig4 #ca7 is often found with the above4 ,its frustules are coherent at the angles4 ,the front view 7fig4 #cb f7 is rectangular1 often slightly narrowed in the middle2 and the valves are narrowly linear1 and capitate at the ends2 they are also transversely striated4 ,in ,syndra splendens 7,pl4 ,v4 fig4 #e7 the frustules radiate from a soft gelatinous cushion4 ,they are linear in the front view 7fig4 #d f71 the valves 7fig4 #d s7 being gradually narrowed or attenuated from the middle to the ends1 and exhibit transverse stri interrupted opposite a middle longitudinal line4 ,in ,campylodiscus costtus 7,pl4 ,v4 fig4 #bg7 the frustules are disk-shaped and curved1 so as somewhat to resemble a saddle4 ,the markings consist of central dots1 with radiating coarse flutings4 ,nitzschia minutissima 7,pl4 ,v4 fig4 #bh7 has oblique valves1 i4 e4 the front half of the suture is not opposite the back portion2 the valves 7fig4 #bi7 are constricted in the middle1 and the ends narrowed and prolonged4 ,the markings consist of a row of oblong dots or puncta 7punctum1 a point74 ,this species often forms yellowish layers upon damp paths1 c4 ,in the next group1 the valves have a longitudinal line running down the middle of the valves1 with a little knob or nodule in its centre 7,pl4 ,v4 fig4 #bb s71 both consisting of internal thickened portions of the valves4 ,in ,cocconis placentula 7,pl4 ,v4 fig4 #cc7 the valves are oval1 and the markings consist of longitudinal rows of minute dots1 with a marginal row of puncta2 these markings are invisible under ordinary illumination4 ,in ,gomphonma acumintum 7,pl4 ,v4 fig4 #ag7 the frustules are attached to a branched stalk 7stipes72 they are wedge-shaped or cneate 7cneus1 a wedge7 and transversely striate 7fig4 #ah71 the stri consisting of dots4 ,in ,pinnulria viridis 7,pl4 ,v4 fig4 #bb71 which is very often seen slowly traversing the field of the microscope when a drop of pond-water is examined1 the frustules in the front view are linear1 the valves being elliptic oblong1 and transversely striated1 the stri consisting of furrows4 ,in ,gyrosigma 7,pleurosigma7 attenutum 7,pl4 ,,vi4 fig4 #af7 the valves are sigmoid1 or somewhat resemble a ,greek 7sigma7 in outline1 and the markings consist of rectangularly crossed rows of very fine dots2 in the front view1 the frustules are linear-oblong with truncate ends4 ,tabellria flocculsa 7,pl4 ,,vi4 fig4 #bc7 has the frustules adherent only at the angles1 as in ,ditoma4 ,they are rectangular1 and in the front view exhibit a row of longitudinal dark lines interrupted in the middle2 these have been compared to the vitt of the fruit of the ,umbellifer1 and have received the same name4 ,among the marine species may be mentioned ,melosra nummulodes 7,pl4 ,,vi4 fig4 #i71 in which the frustules are united into a chain or cylindrical filament4 ,this is very common among sea-weeds1 c42 and it illustrates well the process of division of the frustules 7fig4 #aj f74 ,the valves are covered with fine dots1 and near each end of the frustules is a projecting rim encircling it1 and appearing as a curved line extending beyond the margin of the frustule in the front view4 ,in ,actinocyclus undultus 7,pl4 ,,vi4 fig4 #e7 the frustules are separate1 disk-shaped1 and the valves are divided into six equal parts by six rays1 each alternate portion of the surface of the valves being situated on a lower level than those adjacent1 so that an alteration in the focus is required to bring into view the dots on any two adjacent divisions of the valve4 ,the surface of the valves is covered with easily recognized dots4 ,the form of the surface is best seen in the front view 7fig4 #e f7 when the frustule is placed on its edge4 ,rhabdonma arcutum 7,pl4 ,,vi4 fig4 #g71 which is very commonly found attached to sea-weeds1 resembles ,tabellria in the frustules having the vitt 7,pl4 ,,vi4 fig4 #h f74 ,the frustules form short filaments1 attached by a little gelatinous cushion4 ,the valves have transverse stri1 interrupted in the middle 7fig4 #h s74 ,gyrosigma 7,pleurosigma7 angultum 7,pl4 ,,vi4 fig4 #ag7 resembles ,g4 attenutum in the sigmoid form2 but the markings consist of lines crossing each other obliquely2 and these are resolvable into rows of dots 7fig4 #ag a7 under suitable illumination4 ,in ,coscinodiscus raditus 7,pl4 ,,vi4 fig4 #c7 the frustules are disk-shaped1 the valves being elegantly sculptured with easily recognized cell-like markings or dots1 so as to resemble a piece of vegetable cellular tissue4 ,but in some other species the dots are very minute1 and difficult to be shown satisfactorily4 ,these markings consist of depressions or pits in the surface of the valves4 ,that this is the case may easily be seen by examining a fragment of the valve1 when the shadings of the broken ends of the netted thicker portions1 which project like teeth1 strongly contrast with the difficultly distinguishable portions of the thin interspaces4 ,the fossil forms from the ,bermuda deposit are best for the investigation of this structure2 many of these are extremely beautiful microscopic objects1 their markings resembling those on the engine-turned back of a watch4 ,the detection of the finer markings of the ,diatomace1 which1 according to my view1 consist of depressions like those upon the valves of ,coscinodiscus1 is a matter of great difficulty to those who are unaccustomed to the use of the microscope1 and who have not a complete set of apparatus4 ,the main point to be attended to in bringing them into view1 is to use one-sided oblique light1 i4 e4 to turn the mirror by its stem as much as possible to one side1 and then to incline it so as to throw the light upon the object4 ,in this way the valves of the species of ,gyrosigma1 for instance1 appear covered with lines 7,pl4 ,,vi4 figs4 #af and #ag72 but the lines are spurious1 i4 e4 they are the optical expression of rows of minute dots 7figs4 #af a1 #ag a72 and when oblique light is thrown upon the valves from all sides1 by means of a special achromatic condenser1 in which the central rays are excluded1 the dots become distinct1 and the markings resemble those on the valves of ,coscinodiscus4 ,to show the finer dots clearly1 a valve should be crushed1 so as to obtain a fragment as flat as possible2 for the surface of the valves is curved more or less in all the species4 ,the valves of ,g4 angulatum are generally used to test the quality of the object-glasses of the microscope1 and also for practice in 8making out0 the lines and dots2 there are1 however1 many ,diatomace more difficult4 ,as the nature of these markings is a disputed point1 the discussion of which is not adapted for an elementary work1 ,i must refer for further details to the #8,micrographic ,dictionary2' it may be remarked1 however1 that some observers have regarded them as cells1 and others as elevations or tubercles on the surface of the valves4 ,the preparation of the valves for showing the markings should be effected by burning the frustules1 or the mass containing them1 on a strip of platinum-foil over a spirit-lamp4 ,the incinerated mass should then be transferred to a slide1 and the valves separated with the greatest care by a bristle mounted in a hair-pencil stick under a low power of the microscope4 ,this is1 however1 a substitute for the proper method1 which is dangerous in the hands of one unpractised in chemical manipulation4 ,it is this3--,the mass of ,diatomace 7the water containing it having been carefully poured off as far as possible7 is put into a ,florence oil-flask1 and strong nitric acid 7aquafortis7 gently added1 more than sufficient to cover it4 ,the mixture is then carefully boiled over a spirit-lamp for some time4 ,when it is cold1 distilled water is added1 the whole shaken1 and allowed to settle4 ,the watery part is then gently poured off1 more water added1 and this poured off after settling1 and the process repeated until a drop of the water evaporated to dryness on a slide leaves no residue4 ,the ,diatomace then form a white sediment at the bottom of the water1 and can be transferred to a slide with a dipping-tube4 ,the drop is then dried with a gentle heat1 and the valves mounted as dry transparent objects 7p4 #ab74 ,if the valves have coarse markings1 they may be mounted in balsam2 but if the markings are fine1 balsam makes them much more difficult of detection4 ,many of the most beautiful ,diatomace are found in the fossil state2 and specimens of these are sold already mounted4 ,i would advise those unacquainted with them to purchase a slide of the 8,bermuda0 or 8,richmond0 earth1 which abounds in the species of ,coscinodiscus2 and of the 8,san ,fiore deposit10 which contains many species of ,epithemia1 ,navicula1 ,pinnularia1 c4 ,these may be procured from ,mr4 ,norman1 #agh ,city ,road1 or from the microscope-makers4 ,,volvocin,e4--,the ,volvocine are inhabitants of clear fresh-water pools1 on heaths and bogs4 ,they are very minute1 of a rounded or plate-like 7tabular7 form1 of a green colour1 and are pretty readily distinguished from most of the other ,alg by their free motion2 for they swim about in the water like animals1 as which they were formerly considered4 ,they consist usually of groups of thick-walled soft cells1 each being furnished with one or two cilia1 by means of which the movement of the compound bodies is produced4 ,in the beautiful ,volvox globtor 7which is not uncommon7 the cells form a hollow sphere 7,pl4 ,,vi4 fig4 #ah71 studded with exceedingly minute green spots or zoospore-like bodies1 representing the green endochrome of the component cells1 and from each of which very fine radiating lines extend1 so as to give the surface a netted appearance2 the lines consisting of delicate processes of the endochrome1 which may be compared with those existing in the cells of the hairs of ,tradescantia4 ,in the interior of the parent globes are often seen several young organisms1 usually eight1 of a deep green colour2 these escape by the rupture of the parent1 so as to form independent beings4 ,sometimes they are found of a yellow colour1 and furnished with a thick transparent coat2 these are called 8resting spores10 as they remain for some time before undergoing their full development4 ,the cilia of ,volvox1 of which there are two to each of the component cells1 are difficult to detect2 they are best seen when the organism is dried without a cover1 or after moistening them with a little solution of iodine1 which dyes them brown4 ,synra volvox 7,pl4 ,,vi4 fig4 #ac7 is a still more minute member of this family1 and is often found rolling along among ,conferv4 ,the greenish zoospore-like bodies of this ,alga have one cilium only1 and arise from a common centre by a narrowing of the base 7fig4 #ad74 ,in ,gnium pectorle 7fig4 #aa a7 the green bodies1 which are sixteen in number1 and furnished each with two cilia1 are grouped into a flat square plate2 and in the very minute ,gonium tranquillum 7fig4 #aa c7 these bodies are also sixteen in number1 and arranged in a tabular form1 but are without cilia4 ,,siphona,,ce4--,the structure of this family may be illustrated by the genus ,vauchria1 of which two or three species are common on damp ground or in freshwater pools1 forming a green layer4 ,at first sight1 the filaments of which the little plants consist appear like those of a stout ,conferva2 but on close examination they are found to be branched1 and not jointed1 consisting of a single cell from end to end 7,pl4 ,,vi4 fig4 #bf74 ,the reproduction is effected by the agency of two kinds of organs1 antheridia and capsules 7sporangia71 situated near each other 7fig4 #bf a7 on the walls of the filaments1 of which they are protrusions or outgrowths--their cavities being separated from that of the filament by a partition or septum4 ,the antheridia produce spermatozoa1 and the sporangia each a spore1 the one fertilizing the other in the ordinary manner4 ,in addition to this method of fructification1 zoospores are also produced--the ends of the filaments becoming swollen1 the contents cut off by a septum1 and forming single large zoospores covered with cilia1 the further development of which resembles that occurring in the ,confervace4 ,,oscillatoria,,ce4--,the members of this family are commonly found in stagnant water or on shaded damp ground1 especially in the cold seasons of the year1 forming green strata or masses4 ,,plate ,,vi4 ,,page #hd4 ,,freshwater ,,alg4 ,fig4 #a4 ,oscillatoria autumnalis4 #b4 ,oscillatoria nigra4 #c4 ,coscinodiscus radiatus4 #d4 ,nostoc minutissimum4 #e4 ,actinocyclus undulatus4 #f4 ,bacterium4 #g4 ,rhabdonema arcuatum4 #h4 ,rhabdonema arcuatum1 prepared frustules4 #i4 ,melosira nummuloides4 #aj4 ,melosira nummuloides1 prepared frustules4 #aa4 a1 b1 ,gonium pectorale3 #aa c4 ,gonium tranquillum4 #ab4 ,spirulina oscillarioides4 #ac4 ,synura volvox4 #ad4 ,synura volvox4 #ae4 ,gyrosigma attenuatum1 front view4 #af4 ,gyrosigma attenuatum1 side view2 #af a1 portion of a valve4 #ag4 ,gyrosigma angulatum2 #ag a1 portion of a valve4 #ah4 ,volvox globator4 #ai4 ,glocapsa4 #bj4 ,chara vulgaris1 globule4 #ba4 ,chara vulgaris1 portion of filament4 #bb4 ,chara vulgaris1 branch with nucule and globule4 #bc4 ,tabellaria flocculosa4 #bd4 ,tabellaria flocculosa1 prepared frustules4 #be4 ,palmella cruenta4 #bf4 ,vaucheria ,ungeri 7sessilis74 #bg4 ,vaucheria ,ungeri1 capsule4 ,illustration3 ,plate ,,vi4 ,w ,bagg sculp ,london3 ,john ,van ,voorst4 ,oscillatoria autumnlis 7,pl4 ,,vi4 fig4 #a7 occurs everywhere upon damp shaded banks of ditches1 especially when newly made1 forming a greenish-black closely adherent stratum4 ,under the microscope it is seen to consist of innumerable palish-green filaments2 these are jointed or transversely striated1 some being straight1 others curved1 the ends often exhibiting a writhing or worm-like movement4 ,the appearance of these fibres is peculiar1 seeming as if they were solid throughout1 and so differing from that of the ,confervace1 in which the cell-walls are readily distinguishable from the cell-contents4 ,the fibres easily break across at the joints2 and the last few segments are often narrowed and rounded1 so as to form a blunt point4 ,when they have been left in water1 they exhibit colourless tubular sheaths surrounding and extending beyond them4 ,these sheaths consist of the consolidated outer portions of the cell-walls2 for when the cells undergo transverse division1 and expand by growth in the direction of the length of the filament1 the original septa or inner walls are broken through1 and their remains may often be seen on the inner surface of the sheath1 appearing as little teeth4 ,oscillatoria nigra 7,pl4 ,,vi4 fig4 #b7 is another very similar species1 forming blackish-green masses1 and is common in ditches4 ,it has longer filaments than the last1 with narrowed and slightly curved ends2 and the endochrome is distinctly granular4 ,in two other genera of this family1 ,vibrio and ,spirulna1 the filaments are spiral4 ,vibrio spirillum is excessively minute1 colourless1 and found in decomposing vegetable mixtures4 ,the short filaments move rapidly through the water1 with a corkscrew-like motion4 ,in ,spirulna oscillariodes 7,pl4 ,,vi4 fig4 #ab71 which is more rarely found in clear pond-waters among ,conferv1 the filaments are greenish1 and form a beautiful simple spiral1 resembling that of a very slender spiral vessel4 ,lyngbya murlis 7,pl4 ,v4 fig4 #b7 is very common on damp walls1 gravel walks1 c4 ,it forms a bright grass-green layer1 consisting of somewhat rigid curled filaments4 ,the endochrome is usually broader than long2 and the cells of the filaments are often found empty1 the endochrome having escaped in the form of gonidia4 ,pl4 ,,vi4 fig4 #f represents a species of ,bactrium which is not uncommon in decomposing vegetable liquids2 the filaments are short1 curved1 pointed at the ends1 and have four joints4 ,fig4 #bf represents a ,schizognium1 found upon damp paths4 ,the filaments resemble those of ,lyngbya1 but are united in pairs4 ,fig4 #c represents a filament of a ,ulothrix1 which is common in freshwater pools1 showing the curious manner in which the endochrome is arranged in the cells1 forming bands partially lining the cell-walls4 ,,nostocha,,ce4--,two species of the typical genus ,nostoc will serve to represent this family4 ,nostoc commne is found on damp ground or in ponds1 and forms to the naked eye firmish1 olive-green1 skin-like1 plaited masses1 an inch or more in diameter4 ,under the microscope it is seen to consist of numerous beaded fibres1 imbedded in worm-like gelatinous sheaths2 these are curved and interwoven to form the compound mass4 ,in the middle of many of the filaments is an enlarged colourless cell1 called the vesicular cell1 which is related to the reproduction1 but in a manner not yet determined4 ,nostoc minutissimum 7,pl4 ,,vi4 fig4 #d7 forms solid gelatinous bluish-green masses1 varying in size from a pin's head to a pea2 it is found upon unhealthy water-plants kept in glass vessels4 ,the component filaments are very slender1 wavy1 and the sheaths often have a brownish tinge4 ,,ulvace4--,these ,alg are mostly marine--some1 however1 being found in brackish or fresh water1 or on damp ground1 thatch1 moss1 c4 ,they are generally of considerable size1 forming flat or tubular fronds1 often several inches long1 a few being filamentous4 ,they consist of one or more sheets or layers of cells1 containing mostly green endochrome4 ,this at first fills the cells1 but subsequently becomes converted into single spores1 or subdivided into numerous ciliated zoospores4 ,ulva latissima is very common on the sea-coast1 being found attached to stones1 shells1 c4 ,it forms a broad1 flat1 green1 rounded or oblong1 thin frond1 wavy and crumpled at the margins1 and from #f to #ah inches in length4 ,the minute cells form two layers1 adherent to each other4 ,the zoospores formed are numerous in each cell4 ,enteromorpha compressa 7,pl4 ,,iv4 fig4 #ca7 is also common in the sea and in brackish ditches2 it is often found floating4 ,the frond is green1 tubular1 flattened or compressed1 and branched1 the branches being usually simple and narrowed at the base4 ,the frond consists of two layers of minute cells1 separated by a space rendering it hollow4 ,the zoospores are numerous in the cells 7fig4 #cb74 ,,palmella,,ce4--,these ,alg are found in fresh or salt water1 or on damp earth1 wood1 c4 ,they are green or red1 forming round or irregular masses or strata4 ,they consist of loosely connected cells1 imbedded in a gelatinous mass or matrix1 thus forming a frond4 ,chlorococcum vulgre 7,pl4 ,,ii4 fig4 #a7 is very common upon the bark of elm-trees1 palings1 c41 forming a green granular crust4 ,it consists of minute rounded or oval cells1 mostly undergoing division into twos1 fours1 or eights4 ,these cells are attached to the sides or ends of very fine colourless filaments4 ,it is most probable that this organism1 which is usually placed among the ,alg1 consists of the gonidia of a ,lichen4 ,chlorococcum murorum forms a somewhat similar but soft and thin green layer1 upon damp walls or other porous bodies4 ,it consists of very minute oval green cells1 with thick walls1 and imbedded in the ends of prolongations of a gelatinous matrix4 ,palmella cruenta 7,pl4 ,,vi4 fig4 #be7 forms a portwine-red layer at the bottom of damp walls or on the ground4 ,it is composed of pale red cells1 imbedded in no definite order in a colourless gelatinous matrix4 ,the cells are filled with red granules1 and are often found undergoing division4 ,pl4 ,,vi4 fig4 #ai represents a species of ,glocapsa1 in which the cell-envelopes do not soften and unite to form a gelatinous matrix1 as in ,palmella and other members of the family1 but are persistent4 ,this species occurs in fresh water containing ,conferv4 ,,chara,,ce4--,this family consists of the single genus ,chra1 the systematic position of which is not agreed upon by authors2 as however its structure will be better understood after what has been gone over1 it may be conveniently considered here4 ,there are several species of ,chara1 the one illustrated1 ,chara vulgris 7,pl4 ,,vi4 fig4 #ba71 being commonly found in ditches and pools4 ,it consists of long main stems1 often a foot in length1 which are branched1 and surrounded at tolerably regular intervals by whorls of branchlets4 ,in some species1 the stems and branches consist simply of elongated cells1 arranged end to end2 while in others1 of which ,chara vulgaris is one1 the central cells are surrounded by a number of narrower spirally arranged cells1 forming an outer coating4 ,the ,char have long formed interesting microscopic objects1 on account of the circulation of the protoplasm being visible in the cells1 as in the hairs of ,tradescantia4 ,this is best seen in those species in which the outer layer of cells is absent from the stems1 and which were formerly arranged in a separate genus 7,nitella74 ,but it may also be seen in the stems and especially the young branchlets of any of the other species2 and as the granules of the protoplasm are large1 the phenomenon is more easily witnessed than in ,tradescantia4 ,the fructification consists of two kinds of organs1 viz4 red globules 7,pl4 ,,vi4 fig4 #bb7 representing the anther-organ1 and green capsules 7fig4 #bb71 or nucules1 corresponding to the ovaries4 ,the structure of the globules is very curious4 ,their transparent walls 7fig4 #bj7 consist of eight somewhat triangular plates1 each of which is composed of cells radiating from a centre2 and from the inside of each of these centres arises a tubular cell extending to the middle of the globule1 the unattached ends giving origin to numerous colourless coiled filaments1 consisting of minute cells arranged end to end1 each containing a very minute coiled spiral fibre1 to which are attached two exceedingly slender cilia4 ,these ciliated fibres are the spermatozoa4 ,the capsules or nucules 7fig4 #bb71 which are situated near the globules1 are urn-shaped1 coated with spiral cells1 and crowned with five shorter cells4 ,when the globules are ripe1 they become ruptured by the separation of the valves2 and the spermatozoa1 escaping from the cells of the coiled filaments1 swim about and enter a canal in the capsules to fertilize the ovule contained within4 ,the ,char grow readily in a glass jar of fresh water1 with a few pebbles at the bottom2 and if the plants be not overgrown with ,confervoids1 the fructification will continue to be produced almost throughout the year4 ,the circulation is best seen in the whorled branchlets1 a portion of the growing ends being placed in a live-box1 or simply laid upon a slide in water and covered with thin glass4 ,preservation4--,the ,alg are best preserved in two ways1--the entire fronds being dried upon paper under pressure1 as directed for the ,ferns2 and small portions1 showing the minuter structures and fructification1 being mounted in chloride of calcium or glycerine4 ,if it is required to preserve the marine ,alg according to the first method1 they should first be immersed for a time in fresh water1 to dissolve out the saline matters derived from the sea-water1 which would keep them damp and ultimately spoil them4 ,after these matters have been removed1 the fresh water should be changed1 and pieces of paper placed beneath them while suspended in the water2 on withdrawing the paper carefully1 keeping the ,alg at the same time spread out1 they may be made to retain the required position2 and when the water has drained away1 and the remaining moisture has mostly evaporated1 they may be submitted to pressure in a press4 ,the ,confervoid ,alg may be conveniently spread out upon paper and preserved in the same manner1 as some of the distinguishing characters are founded upon their appearance in the dry state1 their adhesion to the paper1 c4 ,moreover they can then at any time be minutely examined1 by the immersion of a small portion in water4 ,,chapter ,,viii4 ,,lichens4 ,the ,lichens are found growing upon the bark of trees1 old palings1 c4 ,those most easily seen with the naked eye form grey or coloured dryish patches or pendulous tufts2 while the smaller ones are singly easily overlooked1 from their minute size and close adhesion to the mtrix or body upon which they grow1 forming1 by their aggregation1 the grey or otherwise-coloured dry and brittle coatings of almost every tree or decaying branch4 ,the ,lichens derive their nourishment from the air1 and not from the matrix--in this respect differing from the ,fungi1 with some of which1 as we shall presently see1 they agree in the structure of the fruit4 ,the structure of the ,lichens is simple1 no distinction of root1 stem1 and leaves existing in them1 although certain dry root-like fibres exist in many of them1 by which the plant is fixed to the matrix4 ,the whole consists mainly of a frond or thallus 71 a leaf74 ,this is either raised above the surface of the matrix in a shrubby form1 or spread upon the surface as a flexible lobed layer 7,pl4 ,,ii4 fig4 #b71 or it is dry and brittle 7crustaceous7 and closely adherent 7,pl4 ,,ii4 fig4 #bf74 ,the fructification consists of little saucers1 disks1 or streak-like furrows1 often of a different colour from the thallus1 the structure of which will be best illustrated by reference to a few common species4 ,,parmelia,,ce4--,parmlia parietna 7,pl4 ,,ii4 fig4 #b7 is a very common ,lichen1 found on the bark of trees1 on old palings1 c4 ,it is of an orange-yellow colour1 the thallus being flat1 lobed1 and scalloped 7crenate7 at the margins4 ,the structure of the thallus may serve to represent that of most of the ,lichens4 ,it consists of three layers1--an upper cortical or epidermic layer1 which is continued over the margins to the under surface of the thallus1 to form the under layer2 and between these is the middle or medullary layer4 ,the medullary layer consists of interwoven fibres1 which are more closely packed towards the upper and under surfaces1 so as to give them a cellular appearance4 ,near the upper part of the medullary layer1 a number of minute rounded green cells exist1 lying loosely in its meshes 7,pl4 ,,ii4 fig4 #d a74 ,these green cells 7gonidia7 appear to correspond to the buds of the higher plants1 and1 when detached from the plants1 they are capable of growing into new individuals4 ,on the upper surface of the thallus of ,parmelia 7fig4 #b7 the fructification may be observed4 ,this consists of saucers or shields 7apothcia1 1 a repository71 formed of a raised and expanded portion of the thallus 7fig4 #c71 and containing the spores4 ,the spores are enclosed in closely set upright cells1 or spore-sacs 7figs4 #d b and #e b71 called asci 71 a bottle7 or thec2 and intermingled with the asci are filaments1 enlarged and coloured at the ends 7paraphyses71 which are probably abortive asci4 ,in systematic works upon the ,lichens1 the saucers and their contents are included in the term apothecia1 the saucer alone being called the excipulum 7excipulum1 a receiver72 the mass of asci and paraphyses forming the nucleus or thalmium 71 a bed74 ,the yellow spores are very minute1 each ascus containing eight of them1 and they are divided by a transverse partition or septum4 ,near the margins of the lobes of the thallus are small dark points4 ,these are the pouting mouths of little capsules 7spermogonia7 sunk in the substance of the thallus1 and containing numerous filaments1 terminated by very minute stick-shaped bodies 7spermatia71 which break off and escape through the orifices of the capsules4 ,these are probably the representatives of the anthers of flowering plants and of the antheridia of the ferns4 ,they are1 however1 so difficult to find and examine1 that ,i must refer to the ,dictionary for a further description and figures of them4 ,,lecidin,e4--,this family contains the genus ,cladnia1 three or four species of which are common on boggy heaths1 banks1 c41 viz4 ,cladonia coccifera1 the ,scarlet ,cup-moss 7,pl4 ,,ii4 fig4 #ba72 ,c4 pyxidta1 the ,common ,cup-moss 7,pl4 ,,ii4 fig4 #bc72 ,c4 vermiculris 7,pl4 ,,ii4 fig4 #bb72 and ,c4 rangiferna1 the ,reindeer ,moss 7,pl4 ,,ii4 fig4 #bd74 ,the thallus of these ,lichens forms little rounded irregularly overlapping scales1 with scalloped edges1 overgrowing the surface upon which the ,lichens are found4 ,the fruit-stalks1 or podtia 71 a foot71 are hollow 7fistulose71 and either simple and dilated into cups 7,pl4 ,,ii4 fig4 #bc71 or branched with the corners or angles between the adjacent branches perforated4 ,the apothecia in the young state resemble those of ,parmelia on a small scale2 but as they approach maturity1 the centre becomes pushed up1 so that the spore-layer is extended over the ends of the stalks4 ,in ,c4 coccifera and pyxidata the cups are proliferous at the margin2 i4 e41 branches upon which the apothecia are placed arise from it4 ,the asci and paraphyses are very minute1 but do not differ essentially in structure from those of ,parmelia4 ,in ,c4 vermicularis the podetia are pointed and more solid than in the other species1 the apothecia forming very minute spots at their apices4 ,,graphid,e4--,to this family belong ,grphis scripta 7,pl4 ,,ii4 fig4 #bf7 and ,opegrapha betulna 7,pl4 ,,ii4 fig4 #cj74 ,these little ,lichens are easily overlooked1 from the thin and but slightly raised thallus being only visible to the naked eye as a discoloration of the bark of the trees upon which they grow2 while the fructification is very minute1 forming little black streaks or lirell 7lira1 a furrow71 irregularly arranged1 and resembling somewhat the letters of some of the ,oriental alphabets4 ,in ,graphis scripta 7fig4 #bf7 the thallus is thin1 somewhat membranous1 smoothish1 shining1 greyish white1 and faintly bordered with black4 ,the lirell 7fig4 #bg7 are partly sunk in the bark1 winding and narrow1 some being simple1 others branched2 and they are surrounded by a raised border1 formed by the thallus4 ,the lirell are lined at the sides with a black 7carbonaceous7 layer or excipulum1 within which are situated the asci and paraphyses4 ,the spores 7,pl4 ,,ii4 fig4 #bi7 are #h-;cleft1 the segments being again divided longitudinally into little spores or sporidia4 ,in ,opegrapha betulina 7,pl4 ,,ii4 fig4 #cj71 which is found on the bark of the birch-tree1 the thallus is thin1 dirty yellowish white1 bordered with black4 ,the lirell 7figs4 #ca1 #cb7 are mostly simple1 without a raised border of the thallus1 and the excipulum forms a complete lining to them4 ,the spores 7fig4 #cc a7 are #c-;cleft1 and taper at the ends4 ,,calici,e4--,calicium clavellum 7,pl4 ,,ii4 fig4 #f7 is a pretty little ,lichen1 growing upon old boards and farm-buildings4 ,the thallus is granular and greyish white4 ,the apothecia 7fig4 #g7 are stalked and black1 but of a lighter colour than the mass of spores forming the nucleus4 ,the spores are very minute1 black1 oblong1 and divided by a transverse septum4 ,the ,lichens are divided into two ,orders1 according to whether the apothecia are open before the spores are ripe1 as in the species noticed above1 or whether the apothecia only open to discharge the ripe spores4 ,the first ,order forms the ,gymnocarpi 71 naked1 1 fruit72 the second forms the ,angiocarpi 71 vessel1 capsule74 ,preservation4--,the ,lichens are readily preserved1 on account of their dry nature2 they need simply be kept in a dry place1 and glued to pieces of card4 ,if room is an object1 they may be dried under pressure1 as in the case of the flowering plants4 ,when re-moistened1 the minute structures may be easily made out by sections4 ,the smaller ones may be mounted dry1 in cells made of the wax cement 7p4 #af74 ,the minute structures keep well in chloride of calcium or glycerine4 ,,chapter ,,ix4 ,,fungi4 ,the ,fungi form the lowest class of plants3 as examples of them1 may be mentioned mushrooms1 toadstools1 puff-balls1 the mould of paste1 the blue mould of cheese1 c4 ,the more minute ,fungi are very common1 forming beautiful microscopic objects1 although they are rarely studied by the microscopic observer4 ,fungi live usually upon rotting or decaying vegetable substances1 as rotten wood1 the dead leaves and stems of plants1 c42 but sometimes they are found upon living plants1 and some of them exist upon decaying animal matters1 and even in living animals4 ,fungi exhibit no separation of root1 stem1 or leaves1 as exists in the higher plants2 nor do they contain chlorophyll1 the presence of which is so generally associated with the idea of a plant4 ,but they consist of aggregations of mostly elongate cells1 forming branched and interlacing colourless fibres1 buried like roots in the substance 7matrix7 upon which they grow1 and from which they derive their nourishment2 this portion of the ,fungus is called the myclium 71 a fungus74 ,the portion of the ,fungus projecting beyond the surface of the matrix is the fructification2 and this is the part usually called the fungus1 the mycelium being overlooked by a casual observer4 ,so that here we have a character distinguishing the ,fungi from the ,lichens1 which derive their nourishment from the air1 and not from the matrix4 ,the absence of the green cells1 or gonidia1 forms another character by which the nearly allied members of this class of plants can be distinguished4 ,,plate ,,vii4 ,,page #if4 ,,fungi4 ,fig4 #a4 ,agaricus micaceus3 a1 gills4 #b4 ,agaricus campestris3 a1 spores2 b1 basidia4 #c4 ,physarum album1 on a piece of stick4 #d4 ,physarum album1 spores4 #e4 ,uredo segetum1 spores4 #f4 ,uredo caries1 spores4 #g4 ,uredo candida1 on leaf of ,shepherd's ,purse 7,capsella73 s1 spores4 #h4 cidium grossulari1 sorus4 #i4 cidium grossulari3 p1 spore-capsules 7peridia72 s1 anther-capsules 7spermogonia74 #aj4 ,nemaspora crocea3 a1 spores4 #aa4 ,torula casei4 #ab4 ,torula herbarum1 on a piece of stick4 #ac4 ,torula herbarum1 spores4 #ad4 ,phragmidium bulbosum1 on bramble-leaf4 #ae4 ,phragmidium bulbosum1 stylo-spores and paraphyses4 #af4 ,puccinia graminis1 on a piece of straw4 #ag4 ,puccinia graminis1 spores4 #ah4 ,sporocybe alternata1 filament and spores4 #ai4 ,botrytis parasitica1 on ,shepherd's ,purse4 #bj4 ,botrytis parasitica1 spores and filaments4 #ba4 ,rhinotrichum1 species of4 #bb4 ,rhinotrichum1 heads of spores4 #bc4 ,rhinotrichum1 spores detached4 #bd4 ,rhinotrichum1 spores4 #be4 ,penicillium glaucum4 #bf4 ,penicillium glaucum1 head of spores4 #bg4 ,coremium leucopus4 #bh4 ,tubercularia vulgaris4 #bi4 ,tubercularia vulgaris1 divided receptacle4 #cj4 ,tubercularia vulgaris1 filaments4 #ca4 ,tubercularia vulgaris1 spores4 #cb4 ,sphria fragiformis4 #cc4 ,trichothecium roseum1 on a piece of stick4 #cd4 ,trichothecium roseum4 #ce4 ,trichothecium roseum1 filaments and spores4 ,illustration3 ,plate ,,vii4 ,w ,bagg sculp ,london3 ,john ,van ,voorst4 ,the fructification of the ,fungi occurs in two distinct forms1 in one of which the seeds or spores are naked1 and situated at the ends of slender cells or filaments1 whilst in the other the spores are contained in usually flask-like cells1 called asci1 similar to those occurring in the ,lichens4 ,in a few ,fungi1 antheridial organs1 called spermogonia1 as in the case of the ,lichens1 have also been detected4 ,the ,fungi are divided into six ,orders1 from each of which a few species may be selected to illustrate their structure more in detail4 ,,hymenomyce,,tes 71 membrane1 1 fungus74 ,this is the highest ,order of ,fungi1 containing a large number of genera and species2 as examples of which may be mentioned the common ,mushroom1 ,toadstools1 c4 ,their general structure may be illustrated by the examination of the common ,mushroom 7,agaricus campestris72 the species figured 7,pl4 ,,vii4 fig4 #a71 however1 being ,agaricus micceus1 which is common at the root of trees1 the bottom of decaying posts1 c4 ,the vegetative part of the fungus consists of a cotton-like mycelium1 which is composed of slender1 colourless1 interwoven filaments1 popularly known as the spawn4 ,the portion commonly called the mushroom corresponds to the fructification1 and consists of certain parts visible to the naked eye4 ,these are an expanded portion at the top1 forming a hemispherical cap1 receptacle1 or pleus 7pileus1 a cap71 and a stalk1 or stpes1 upon which the cap is supported4 ,on the under surface of the cap are a number of nearly parallel1 radiating1 dark-coloured plates or gills1 somewhat resembling the gill-plates of a fish4 ,the dark colour of the gills arises from the presence of the spores1 which are coloured1 although in some species they are white4 ,the surface of the gills1 upon which the spores are situated1 is called the hymnium 71 membrane74 ,the spores 7,pl4 ,,vii4 fig4 #b a7 are microscopic and very minute1 and are situated at the ends of little stalks or points 7,pl4 ,,vii4 fig4 #b b71 called sterigmata 71 a prop71 which are four in number1 and consist of prolongations of the colourless cells of the hymenium2 and these cells are the basidia 71 a little base74 ,the detection of the basidia requires great care1 as they are very minute and transparent2 the best way to observe them is to cut a very small portion from the uninjured edge of one of the gills with a fine pair of scissors1 and to examine it in water4 ,if the gills have been bruised1 the spores are easily rubbed off1 and their connexion with the basidia destroyed4 ,in the young state of the ,mushroom1 the fructification appears as little knobs upon the spawn or mycelium4 ,upon cutting these through perpendicularly1 the cap and stalk are found to be enclosed in a skin or wrapper1 called the volva 7volva1 a wrapper71 and the margin of the cap is continuous with the surface of the stalk1 the connecting membrane forming the veil1 or vlum 7velum1 a veil74 ,as the ,fungus grows1 the cap rises and bursts the volva1 which withers and disappears2 and the veil is torn through1 the portion remaining in connexion with the stalk encircling it as a collar or ring 7annulus74 ,merlius lachrymans1 the ,dry-rot ,fungus1 which belongs to the same family 7,agaricni7 as the ,mushroom1 deserves notice from its very destructive action upon decaying timber4 ,the filaments of the mycelium may readily be detected in the rotting wood by examining a thin section in water4 ,the receptacle forms a yellowish-orange or brownish flattened mass1 some inches in breadth1 with white downy margins2 and the surface exhibits folds arranged so as to form large irregular pores1 instead of gills as in the ,mushroom4 ,in other families the cap and stalk appear fused together and undistinguishable2 or the fructification assumes the form of the cap or the stalk only1 and the hymenium does not form gills4 ,thus in the family ,polyporei 7the members of which are common on the trunks of trees and on rotten posts1 and some of which are very large7 the basidia are situated upon the inner surface of tubes immersed in the under part of the mass1 their orifices forming minute pores1 yet visible to the naked eye4 ,in other families the basidia are placed upon the outer surface of a club-shaped or branched receptacle 7,clavarini71 or upon external prickle-like points 7,hydnei71 c4 ,in the family ,tremellini the receptacle forms a gelatinous mass1 and the basidia are situated upon its surface1 terminating the filaments of which it is composed4 ,one species1 ,dacrymyces stilltus1 is very common on fir posts in the winter and spring1 forming little roundish1 yellowish-orange1 cushion-like masses4 ,,gasteromyce,,tes 71 belly1 hollow1 1 fungus74--,this order of ,fungi1 which contains the ,puff-balls and many others not readily procured1 must be very briefly noticed4 ,the spores are contained in a capsule or peridium 71 a little bag7 which is often of large size1 and are situated upon a hymenium forming folds1 partitions 7septa71 or a lattice-work4 ,a small species1 ,physrum album 7,pl4 ,,vii4 fig4 #c71 is often found growing upon rotten stems of plants and decaying sticks4 ,the capsules are minute1 grey1 brittle1 and black within1 from the presence of the spores 7fig4 #d71 which are lens-shaped1 and arise from the ends of short filaments4 ,,coniomyce,,tes 71 dust1 1 fungus74--,this ,order contains some beautiful microscopic ,fungi1 several of which are very common4 ,many of them grow upon living plants1 while others are found upon decaying stems1 sticks1 c4 ,the mycelium consists of inconspicuous1 fine filaments1 which run beneath the epidermis and bark of leaves and stems1 or exist in the intercellular passages1 the fruit bursting through the surface4 ,the spores are short-stalked1 forming stylospores 71 stalk1 1 seed7 or conidia 71 little dust74 ,but there is great confusion in the descriptions of the spores of the same ,fungus by different botanical authors1 some describing the fruit 7in ,pl4 ,,vii4 fig4 #ae1 for instance7 as composed of rows of spores1 while others regard it as forming a single septate 7septum1 a partition7 or partitioned spore4 ,torula herbrum 7,pl4 ,,vii4 fig4 #ab7 is very common on the decaying stems of plants1 especially those belonging to the ,parsley order 7,umbellifer71 forming greenish-black streaks or patches4 ,the spores 7fig4 #ac7 are grouped into chains or beaded 7moniliform7 rows1 with very short stalks1 and these are crowded to form the black patches visible to the naked eye4 ,under the microscope the spores appear of a brown colour4 ,torula csei 7,pl4 ,,vii4 fig4 #aa7 forms reddish or white patches upon decaying cheese4 ,it consists of branched1 interwoven1 tufted filaments 7flocci71 with comparatively large spherical spores arranged in rows at their ends4 ,nemaspora crcea 7,pl4 ,,vii4 fig4 #aj7 is a very curious member of this ,order1 and is found upon decaying beech-sticks4 ,it appears as an orange-coloured tendril-like gelatinous mass of spores1 bursting through a little pore on the surface of the bark4 ,the spores 7fig4 #aj a7 are very minute1 slender1 and curved1 and under a high power appear jointed4 cidium grossulri 7,pl4 ,,vii4 fig4 #h7 is found very commonly on the leaves of the gooseberry-bush4 ,it forms to the naked eye oval or rounded spots 7sori71 of a red colour2 and on close examination1 the spots appear dotted with yellow points4 ,each point is the orifice of an open capsule 7peridium71 which has burst through the epidermis of the leaf 7,pl4 ,,vii4 fig4 #i p74 ,the capsules are split or lacerated at the margins1 and form little cups containing the spores4 ,the spores are very minute1 yellow1 and are arranged in closely packed moniliform rows4 ,the red colour depends upon the altered chlorophyll of the leaf4 ,on the leaves containing the spore-capsules or peridia will be found smaller1 brownish-yellow capsules 7spermogonia7 partly imbedded in their substance 7,pl4 ,,vii4 fig4 #i s74 ,these contain minute filaments 7sterigmata71 terminated by short rows of rounded cells 7spermatia71 which are supposed to exert an antheridial function4 ,the species of cidium are very numerous1 and many of them are extremely common--as those upon the nettle1 the barberry1 the dandelion1 the wood-anemone1 the violet1 and buttercups4 ,the groups of capsules form exquisite opake objects under a low power of the microscope4 ,phragmidium bulbsum 7,pl4 ,,vii4 fig4 #ad7 is another very beautiful coniomycetous ,fungus4 ,it forms little reddish1 afterwards sooty dots upon the under surface of the leaves of various species of ,bramble 7,rbus74 ,the oblong spores 7fig4 #ae7 are from #b-to #d-septate1 and stalked1 the stalks being swollen or bulbous at the base4 ,the spores1 which appear brown when magnified1 are covered with little knobs 7tuberculate7 on the surface2 and the uppermost little spore or sporidium is terminated by a minute point 7apiculate74 ,among the spores are numerous barren filaments or paraphyses4 ,puccinia graminis 7,pl4 ,,vii4 fig4 #af7 is to be found everywhere upon damp rotting straw1 and upon grasses4 ,it forms sooty irregular streaks1 consisting of densely crowded1 one-partitioned 7uniseptate7 spores 7fig4 #ag71 which appear brown under the microscope4 ,this ,fungus is sometimes called 8mildew40 ,there are numerous other species of ,puccinia which occur upon common plants4 ,urdo segetum is the 8smut0 of wheat1 barley1 and oats--a fungus too well known to the farmer4 ,it forms sooty masses1 bursting through the epidermis of the stalk and ears of the corn1 and soiling the fingers when handled4 ,the spores 7,pl4 ,,vii4 fig4 #e7 are exceedingly minute1 and the stalks are so slender and loosely connected with them that they are not readily detected4 ,under the microscope the spores appear brown and faintly dotted1 this appearance arising from a reticulated structure of the surface1 similar to that of the poppy-seed on a very small scale4 ,urdo cries is the 8bunt0 of corn4 ,it grows within the grain1 filling it with a sooty1 ftid mass4 ,the spores 7,pl4 ,,vii4 fig4 #f7 are considerably larger than those of the last species1 and their surface is distinctly reticulated4 ,they are attached to the filaments of the mycelium1 as in ,uredo segetum4 ,the spores of both these species of ,uredo may be found in most kinds of flour and bread1 especially in those of inferior quality4 ,urdo candida 7,pl4 ,,vii4 fig4 #g7 is another species1 forming white dots upon the leaves of the common ,shepherd's ,purse 7,capsella bursa pastoris7--which is easily recognized by the form and arrangement of the pods 7fig4 #ai74 ,the spores 7s7 are rather large and white4 ,other species of ,uredo are very common upon numerous species of weeds or wild flowering plants2 and they so closely resemble each other that1 when one is known1 the others are easily recognized4 ,usually each species occurs upon a distinct species of plant1 as is the case with parasites generally4 ,in many of them the spots 7sori7 exhibit a thin membrane covering the spores1 which bursts down the middle1 so as to bear some resemblance to a capsule4 ,but there is no true capsule1 the membrane consisting of the epidermis of the leaf or stalk of the plant1 which is raised and torn by the expansion of the growing fungus2 so that the peridium is spurious1 as belonging to the matrix1 and not to the fungus4 ,it may be mentioned here that the so-called species of ,uredo are not truly distinct species1 but are the forms of species of ,puccinia1 ,phragmidium1 c42 so that the latter genera have two kinds of fruit1 one of which is a ,uredo1 the other a ,puccinia4 ,but ,i must refer to the ,dictionary for further details upon this point4 ,,hyphomyce,,tes 71 to weave1 1 fungus74 ,in this1 the #dth ,order of ,fungi1 are contained many of the commonest moulds which are found growing upon decaying substances1 and sometimes upon living plants4 ,the mycelium creeps among the particles of the substance1 or the elements of the tissues1 upon which the ,fungus lives1 in the form of slender threads or filaments4 ,the spores1 which are either simple or partitioned 7septate71 and naked1 occur either singly or in rows at the ends of fine interwoven cottony threads or flocci 7floccus1 a flock of wool71 which are generally very evident to the naked eye4 ,the threads supporting the spores form the pedicels 7pedicellus1 a little foot74 ,in technical descriptions1 these filaments1 which are usually composed of cells arranged end to end1 are said to be septate 7,pl4 ,,vii4 fig4 #bf71 and not jointed1 as in the case of the filaments of the ,conferv1 which are constructed in a similar manner4 ,when not septate1 the filaments are said to be continuous4 ,,stilba,,cei4--,to this family belongs ,tuberculria vulgaris 7,pl4 ,,vii4 fig4 #bh71 which is found upon decaying sticks and branches of trees1 especially the lime-tree4 ,it forms little firm red knobs or tubercles1 each of which is a receptacle4 ,on making a section of a receptacle 7,pl4 ,,vii4 fig4 #bi71 the interior is seen to be paler than the bright red surface1 and a short broad stalk comes into view4 ,the receptacle is composed of crowded cell-filaments1 so short near the base as rather to resemble cellular tissue 7fig4 #cj72 but towards the surface the filaments become extremely slender and branched2 and each branch is terminated by a minute oblong spore1 or a short row of them 7fig4 #ca74 ,if a stick with this ,fungus upon it be kept for some time in a damp place1 short whitish fibres1 branched at the ends1 and visible to the naked eye1 will be seen sprouting from around the base of the receptacle 7,pl4 ,,viii4 fig4 #a74 ,these1 when examined under the microscope1 appear composed of fine filaments 7,pl4 ,,viii4 fig4 #b71 resembling those of ,tubercularia1 and having the minute spores at the ends4 ,after a considerable time1 the entire receptacle of the ,tubercularia becomes resolved into these fibres4 ,in this state the ,fungus assumes the characters of an ,isria1 a genus of a different family of ,fungi 7,isariacei71 so that we have here an ,isaria-form of ,tubercularia4 ,sometimes the tubercles of the ,tubercularia become darker1 almost black1 harder1 and granular on the surface4 ,on making a section of them in this state1 the whole of the under portion of the surface is found to contain little roundish capsules1 containing asci and spores1 and it constitutes ,sphria fragiformis 7,pl4 ,,vii4 fig4 #cb74 ,as the ,sphria is the more complex and highly organized condition of this ,fungus1 the other two conditions must be regarded as forms1 and not as species of separate genera4 ,,dematie,i4--,in this family the filaments upon which the spores are placed are not compacted as in ,tubercularia1 but separate2 and they are of a dark brown or black colour4 ,sporocybe alternta 7,pl4 ,,vii4 fig4 #ah7 is occasionally found upon decaying vegetable substances1 forming little black velvety spots or patches4 ,the mycelial filaments are exceedingly minute1 septate1 tapering at the ends1 and terminated by a little tuft of pear-shaped cells1 from which the black simple spores arise singly4 ,,plate ,,viii4 ,,page #ajd4 ,,fungi4 ,fig4 #a4 ,isaria-form of ,tubercularia4 #b4 ,isaria-form of ,tubercularia1 filaments4 #c4 ,aspergillus glaucus4 #d4 ,aspergillus glaucus1 filaments and heads of spores2 a1 separate spores4 #e4 ,aspergillus glaucus1 head of spores4 #f4 ,peziza omphalodes4 #g4 ,peziza stercorea4 #h4 ,peziza stercorea1 cup 7receptacle74 #i4 ,peziza stercorea1 asci and paraphyses4 #aj4 ,peziza stercorea1 divided receptacle4 #aa4 ,peziza stercorea1 bristles4 #ab4 ,dothidea typhina1 on leaf-stalk ofgrass4 #ac4 ,dothidea typhina1 surface of patch 7stroma74 #ad4 ,dothidea typhina1 capsules 7perithecia74 #ae4 ,dothidea typhina1 ascus containing spores4 #af4 ,sphria rubella1 on nettle-stem4 #ag4 ,sphria rubella1 asci4 #ah4 ,sphria rubella1 capsules 7perithecia74 #ai4 ,sphria rubella1 ascus and spores4 #bj4 ,sphria bullata1 on piece of stick2 #bj a1 section of tubercle 7receptacle74 #ba4 ,sphria bullata1 asci and spores4 #bb4 ,sphria complanata1 on piece of stick4 #bc4 ,sphria complanata1 tubercles 7receptacles74 #bd4 ,dothidea ulmi1 on elm-leaf4 #be4 ,dothidea ulmi1 asci4 #bf4 ,dothidea ulmi1 section of receptacle4 #bg4 ,dothidea ulmi1 spores4 #bh4 ,chtomium elatum2 #bh a1 spores2 #bh b1 filaments4 #bi4 ,chtomium elatum1 on piece of stick4 #cj4 ,hysterium fraxini1 on piece of stick4 #ca4 ,hysterium fraxini1 receptacle4 #cb4 ,hysterium fraxini1 ascus with spores4 #cc4 ,erysiphe guttata1 on hazel-leaf4 #cd4 ,erysiphe guttata1 capsule4 #ce4 ,erysiphe guttata1 capsule 7conceptacle7 with fulcra4 #cf4 ,mucor mucedo3 a1 columella2 s1 spores4 #cg4 ,acrostalagmus3 a1 spores4 #ch4 ,gall on oak-leaf4 #ci4 ,gall on oak-leaf4 ,illustration3 ,plate ,,viii4 ,w ,bagg sculp ,london3 ,john ,van ,voorst4 ,,muced,,ines4--,many of the ,fungi belonging to this family are extremely common on decaying vegetable substances1 and some are found upon living plants1 to which they are very injurious4 ,to the naked eye they usually appear as mouldy or cottony masses1 either white1 black1 or coloured blue1 yellow1 c4 ,the spores are attached singly or in rows to branchlets arising from the ends of the filaments1 so as to form little heads4 ,botrytis parasitica 7,pl4 ,,vii4 fig4 #ai7 is common upon the flower-stalks of the ,shepherd's ,purse1 forming white mealy patches4 ,the fruit-stalks are comparatively large and thin-walled1 the branchlets being slender1 mostly curved1 and terminated each by a large1 spherical1 smooth1 simple1 white spore4 ,botrytis vulgris is also common on various decaying plants4 ,its filaments are grey1 and the branchlets lobe-like2 the spores being minute1 spherical1 either white or greenish1 and placed simply at the tips4 ,botrytis infestans is the potato-,fungus4 ,it forms white spots upon the under side of the leaves of the potato-plant1 and by some authors is considered to be the cause of the potato-disease4 ,the filaments are branched at the ends1 and terminated by single oval spores1 which are apiculate at the free end1 and contain minute little spores or sporidia4 ,oidium ,tuckeri is the well-known destructive grape-,fungus4 ,it forms white cottony masses upon the vine and its grapes1 the fruit-stalks being short and terminated by one or two end-to-end oblong spores4 ,it appears to be the ,coniomycetous form of another ,fungus 7,erysiphe74 ,trichothcium rseum 7,pl4 ,,vii4 fig4 #cc7 is found upon rotting sticks2 very frequently upon willow-baskets kept in a damp place4 ,it forms little rounded1 slightly raised1 pinkish spots1 less than the size of a pin's head4 ,the branched and septate foot-stalks 7figs4 #cd1 #ce7 are terminated each by a little group of obovate spores1 divided by a transverse partition 7uniseptate74 ,sometimes this little ,fungus is quite white1 at others greenish2 when perfectly ripe1 the spores become oblong4 ,penicillium glacum 7,pl4 ,,vii4 fig4 #be7 is the common ,blue ,mould found upon decaying substances1 as cheese1 c41 the interwoven mycelial filaments often forming large cakes or crusts upon the surface4 ,the septate fruit-stalks 7fig4 #bf7 are fork-branched at the ends1 the branchlets being terminated each by a row of very minute spherical smooth spores4 ,on some decaying substances1 as apples1 gum1 c41 the fruit-stalks are found aggregated into a thick stalk1 the branchlets and spores forming a rounded head1 so that the whole resembles a little blue mushroom 7fig4 #bg74 ,in this form the ,fungus has been placed in a distinct genus1 and called ,cormium lecopus4 ,in other species the spores are pink and white4 ,this little ,fungus is of special interest1 on account of one form of it constituting the yeast-plant1 or yeast as it is commonly called4 ,this consists of rounded or oblong cells1 which grow very rapidly in fermenting liquids by budding--the large quantity of sugar and gluten present favouring the vegetative or simple growing process1 at the expense of the fructifying process4 ,but this is only an instance of what we constantly find in flowering plants1 the use of very rich soil rendering flowers double1 which is really reducing their organs to the state of leaves4 ,when the sugar has become exhausted1 the cells of the yeast become longer and thinner1 as if starved2 they then form a more recognizable mycelium1 which extends to the surface of the liquid1 and produces finally the fruit-stalks and the ,penicillium fruit4 ,aspergillus glacus 7,pl4 ,,viii4 fig4 #c7 is an extremely common mould upon cheese1 jams1 c4 ,it resembles the last in appearance to the naked eye1 except that it has rather a green tinge1 the heads of fruit being much more compact and rounded4 ,the fruit-stalks 7fig4 #d7 are large1 bulbous or inflated at the ends 7fig4 #e71 and from the inflations arise the crowded rows of spores4 ,the spores are rounded1 and rough 7scabrous7 on the surface4 ,on removing most of the spores from the head of fruit1 each row of spores is found to arise from a very short stalk4 ,plate ,,vii4 fig4 #ba represents a beautiful species of ,rhinotrichum1 which is found upon decaying and sickly plants1 and upon rotting sticks1 forming a minute grey mould4 ,the fruit-stalks 7fig4 #bb7 are large1 sparingly branched1 septate or jointed1 appearing brownish under the microscope4 ,their ends are branched1 mostly biternate 7fig4 #bc71 i4 e4 each branch dividing into three branchlets1 and these again into three still finer ones4 ,the ends of the branchlets are inflated1 and coated with little points1 upon each of which a smooth white spore 7fig4 #bd7 is placed4 ,,ascomyc,,tes 71 a bottle1 1 fungus74 ,the ,fungi belonging to this ,order are found upon the stems and leaves of plants1 and upon decaying substances1 as dung1 c4 ,they are usually evident to the naked eye1 some even equalling the ,hymenomycetous ,fungi in size2 and many of them are brilliantly coloured4 ,they are in general distinguishable with facility from the ,fungi of other ,orders1 by the arrangement of the spores in colourless sacs or asci 7,pl4 ,,viii4 fig4 #i71 resembling those noticed in the case of the ,lichens4 ,these asci are usually enclosed in a capsule or perithcium4 ,the mycelium is usually buried in the matrix1 so as not to be conspicuous4 ,helvellcei4--,to this family belongs the large genus ,pezza1 some of the species of which are beautifully coloured1 yet scarcely microscopic4 ,among these may be mentioned ,pezza omphaldes 7,pl4 ,,viii4 fig4 #f71 which forms little red masses upon damp ceilings4 ,it does not possess the ordinary form of a ,peziza1 which is that of a cup fixed at the end of a stalk1 like a mushroom with the cup turned inside out1 the asci lining its interior4 ,peziza coccinea is not uncommon in woods4 ,it is whitish outside1 the interior of the cup being of a brilliant scarlet colour4 ,it is from half an inch to an inch in height4 ,peziza stercorea 7,pl4 ,,viii4 fig4 #g7 is often found upon dung4 ,the surface of the cup of this ,fungus is granular and covered with bristles 7figs4 #h #aa74 ,the cup is concave 7fig4 #aj71 and lined with the asci 7fig4 #i71 among which are simple paraphyses4 ,the ,peziz are excellent ,ascomycetous ,fungi for exhibiting the asci1 as they are more or less soft1 and thus sections of them may be easily prepared1 or they may readily be picked to pieces with the mounted needles4 ,,tuberacei4--,in this family is contained the ,truffle 7,tber cibrium74 ,the asci are situated upon the inner surfaces of the winding canals traversing the substance of the fleshy fruit 7peridium7 of which the truffle consists4 ,,phacidia,,cei4--,to this family belongs ,hystrium fraxini 7,pl4 ,,viii4 fig4 #cj71 which is found upon ash-twigs4 ,the drawn-out capsules or perithecia 7fig4 #ca7 are black and elliptical1 with a longitudinal fissure or orifice1 and contain the asci 7fig4 #cb7 with the spores4 ,,sph,,ri,,cei4--,dothidea typhna 7,pl4 ,,viii4 fig4 #ab7 is a common ,fungus upon the stems of living grasses4 ,it forms an orange-coloured patch or layer encircling the stem1 and covered with little dots4 ,on making a section 7fig4 #ad71 it appears composed of a row of oblong or obovate closely placed capsules 7perithecia7 immersed in and continuous with a finely fibrous receptacular mass 7strma74 ,the asci 7fig4 #ae7 are very slender1 arising in a tuft from the bottom of the capsules1 and containing eight still more slender spores4 ,except under a very high power1 the spores appear as interrupted lines running down the interior of the asci4 ,the little dots visible to the naked eye are the slightly projecting mouths of the capsules1 which are more distinctly seen in the magnified portion of the ,fungus 7fig4 #ac74 ,in the young state1 this ,fungus is whitish4 ,this ,fungus cannot be mistaken for a ,uredo1 two species of which occur upon grasses--,uredo lineris forming yellowish-brown spots1 and ,uredo rubgo yellow spots4 ,dothidea ulmi 7,pl4 ,,viii4 fig4 #bd7 forms black1 slightly raised1 and somewhat star-shaped spots upon the upper surface of the leaves of the elm4 ,in a section 7fig4 #bf7 the cavities are seen1 containing the very delicate asci 7fig4 #be74 ,the spores 7fig4 #bg7 are oval1 with a minute septum at one end4 ,sphria rubella 7,pl4 ,,viii4 fig4 #af7 is extremely common on the dead stems of the nettle1 c4 ,in this ,fungus the black bottle-like perithecia 7fig4 #ah71 containing the asci and paraphyses 7fig4 #ag71 are at first situated beneath the epidermis1 through which they at length burst4 ,the spores 7fig4 #ai a7 are spindle-shaped1 and from four-to seven-septate4 ,when ripe1 they escape by a hole or pore in the neck4 ,sphria complanta 7,pl4 ,,viii4 fig4 #bb7 is another common species1 found in hedges1 on dead sticks of the softer 7herbaceous7 plants1 as the parsley-order 7,umbellifer74 ,here the minute capsules1 which are scattered over the stems1 are at first rounded1 then flattened on the top 7depressed71 the neck being very minute 7fig4 #bc74 ,the spores in this species are exceedingly minute1 oblong1 and not contained in asci4 ,sphria bullta also belongs to this family4 ,it occurs upon decaying birch-sticks1 presenting to the naked eye the appearance represented in ,pl4 ,,viii4 fig4 #bj4 ,the black1 raised tubercles 7receptacles7 in their growth burst through the bark1 splitting the epidermis4 ,they consist of a white stroma 7fig4 #bj a71 in which the bottle-shaped capsules 7perithecia7 are immersed1 the necks projecting slightly above the surface as little points 7papill74 ,the tufted spore-sacs or asci 7fig4 #ba71 with the thread-like paraphyses1 are contained within the capsules2 and within the asci are the densely packed1 very numerous and minute curved spores4 ,another species1 ,sphria disciformis1 is also common on birch-sticks4 ,it differs from the last in the tubercles being perfectly flat2 the spores are also longer1 straight1 and spindle-shaped 7fusiform74 ,,perispor,,cei4--,erysiphe guttta 7,pl4 ,,viii4 fig4 #cc7 is a member of this family4 ,it appears on the under side of the leaves of the common hazel as a pale spot2 and on closely examining it with the naked eye1 little black dots are seen scattered on the surface4 ,these are the capsules 7conceptacles71 which are seated upon straight white filaments4 ,the filaments 7fulcra7 are six or seven in number1 and are placed under the capsule1 like the legs of a stool 7fig4 #cd72 they are rigid1 and swollen or inflated at the base 7fig4 #ce74 ,the asci are broad and short1 and contain only two spores4 ,erysiphe maculris is the very destructive hop-mildew2 and other species are common on various plants4 ,chtmium eltum 7,pl4 ,,viii4 fig4 #bi7 resembles little tufts of brown hairs1 occurring upon decaying herbaceous stems4 ,the capsule 7fig4 #bh7 is crustaceous1 and covered with interlaced1 rough1 branched hairs 7fig4 #bh b74 ,the spores 7fig4 #bh a7 are oval1 with a little point at one end 7apiculate74 ,,physomyc,,tes 71 bladder1 1 fungus74--,the ,fungi belonging to this order include some of the commonest moulds growing upon decaying vegetable substances2 while others are found upon leaves1 c4 ,the flocci are generally very evident2 and the spores are contained in little naked1 bladder-like capsules 7peridola7 at the ends of free filaments4 ,,mucorini4--,in this family we have the common mould of paste1 ,mcor mucdo 7,pl4 ,,viii4 fig4 #cf74 ,it is easily recognized by the little spherical capsules terminating the long and tufted fruit-stalks 7pedicels71 which are perceptible to the naked eye4 ,each capsule consists of a simple enlarged cell1 the cavity of which is separated from that of the stalk by a septum4 ,they are white at first1 subsequently becoming brown and black4 ,the minute crowded spores 7fig4 #cf s7 are at first oblong1 afterwards spherical4 ,in the centre of the capsule is a club-shaped body1 or columella 7fig4 #cf a71 formed by the elevation and inflation of the septum4 ,a beautiful little ,fungus of this family1 apparently referable to the genus ,acrostalagmus 7,pl4 ,,viii4 fig4 #cg71 is sometimes found upon soft decaying stems4 ,the main filaments are soft1 smooth1 and not septate4 ,the pedicels are very brittle1 whorled1 dichotomously branched1 scabrous1 and terminated each by a little scabrous spherical vesicle 7fig4 #cg a71 containing two or three oblong spores4 ,,antennari,i4--,in this family is ,racdium 7or ,antennria7 cellre1 the ,wine-cellar ,fungus1 forming the well-known cobweb-like masses hanging from the walls1 c4 ,the little black capsules are seated upon slender septate filaments1 and contain numerous round spores4 ,in examining leaves with the view of procuring ,fungi1 the reader will most likely meet with the two kinds of bodies represented in ,plate ,,viii4 figs4 #ch #ci4 ,these are not ,fungi1 but galls4 ,they arise from an abnormal growth of the leaf-structures1 produced by the deposition of the eggs of insects 7,cynipid74 ,the well-known oak-apple1 and the red hairy-looking body found upon hedge-roses1 are both galls produced in the same way4 ,examination and ,preservation4--,the examination of the ,fungi scarcely requires any special remarks4 ,they should be viewed first as opake objects under a low power2 and then sections should be made1 or the textures separated with the mounted needles4 ,there is some difficulty in moistening the smaller filamentous ,fungi with water1 which is requisite in the determination of the arrangement of the spores upon the branches4 ,hence the best plan is to lay the ,fungus upon a slide1 apply a cover1 then to add a drop of spirit of wine and afterwards a little water to the edge of the cover4 ,when thus wetted1 the spores may be more or less removed with a wet hair-pencil1 when the ends of the branches will become perfectly distinct4 ,in examination of the dried smaller ,fungi as the ,sphri1 the capsules should be macerated for a time in water4 ,the softer ,fungi are very difficult of preservation in the entire state2 but the sections or minute structures may be mounted in chloride of calcium or glycerine4 ,the harder and drier ,fungi may be preserved by drying and gentle pressure between coarse absorbent paper4 ,they may then be glued to pieces of paper and labelled1 in the same manner as the flowering plants4 ,specimens of the capsules1 as of the ,sphri1 c41 may also be mounted in the dry state1 the asci being preserved in the chloride of calcium or glycerine1 in which liquids most of the smaller ,fungi will keep extremely well4 ,,plate ,,ix4 ,,page #aac4 ,,animal ,,tissues1 c4 ,fig4 #a4 ,blood-corpuscles1 ,human4 #b4 ,blood-corpuscles of ,bird 7,fowl74 #c4 ,blood-corpuscles of ,reptile 7,frog74 #d4 ,blood-corpuscles of ,fish 7,stickleback74 #e4 ,hair of ,bat4 #f4 ,hair of ,mouse4 #g4 ,hair of ,mouse4 #h4 ,hair1 human4 #i4 ,hair1 human4 #aj4 ,wool1 fibre of4 #aa4 ,flax1 fibres of4 #ab4 ,cotton1 fibres of4 #ac4 ,silk1 fibres of4 #ad4 ,feather1 portion of3 a1 barbs2 b1 c1 pinn4 #ae4 ,bone1 section of3 a1 lacun4 #af4 ,cartilage1 section of4 #ag4 ,feather1 downy4 #ah4 ,feather1 downy3 pinna4 #ai4 ,shell1 pearly or nacreous portion of4 #bj4 ,muscle3 a1 cellular tissue2 b1 fibrill2 c1 bundle of fibrill4 #ba4 ,tongue of ,whelk3 a1 natural size4 #bb4 ,scale of ,dace4 #bc4 ,scale of ,perch4 #bd4 ,scale of ,cod4 #be4 ,spermatozoa of ,chub4 #bf4 ,flustra foliacea3 a1 cells of2 b1 animal1 with the tentacles expanded4 #bg4 ,flustra foliacea4 #bh4 ,shell of ,oyster1 brown portion of4 #bi4 ,shell of ,oyster1 prisms of4 #cj4 ,cyclops quadricornis4 #ca4 ,daphnia pulex1 female4 #cb4 ,daphnia pulex1 head of male4 #cc4 ,canthocamptus minutus1 an ,entomostracan4 #cd4 ,cypris tristriata4 #ce4 ,cypris tristriata1 eggs of2 #ce a1 b1 c1 the same hatching4 #cf4 ,acarus domesticus 7,cheese-mite71 female4 #cf994 ,cilia of gills of ,oyster4 #cg4 ,trombidium fuliginosum3 a1 pulp2 b1 mandible2 c1 foot2 d1 natural size2 e1 hair2 f1 hair of ,t4 holosericeum4 #ch4 ,acarus domesticus1 male4 #ci4 ,membranipora pilosa4 ,illustration3 ,plate ,,ix4 ,w ,bagg sculp ,london3 ,john ,van ,voorst4 ,,chapter ,x4 ,,animal ,,elements ,,and ,,tissues4 ,the tissues of which animals consist1 like those of plants1 are primarily derived from cells2 in fact the essential part of the egg or vum1 from which all perfect animals originate consists at first only of a simple cell1 with its nucleus and nucleolus4 ,the animal cell-wall differs from that of the vegetable cell in its softness and delicacy--also in its chemical composition1--the former consisting of albminous 7albmen1 white of egg7 matter1 while the latter is composed of cellular or vegetable-cell substance4 ,there is also a striking difference between vegetable and animal tissues1 in the circumstance that1 while the former retain their cellular condition to a very great extent1 the cells of the latter are frequently so altered by compression and fusion together1 or are obscured by the great development of the cell-contents1 that the cell-form is obliterated1 or can only be discovered by the application of chemical reagents2 and in many instances1 the relation of the tissues to the cell can only be discovered by tracing the growth or development of the latter from its earliest stages4 ,hence the examination of the elements and tissues of animals is not well adapted for those who are unpractised in the use of the microscope2 and in treating of them1 we shall simply notice a few which are most easily examined1 beginning with those found in animals belonging to the subkingdom ,vertebrta 7vertebra1 a spine-bone74 ,,mamm,,lia4--,the animals belonging to this class suckle their young2 and their blood-vessels contain red blood4 ,blood4--,this blood consists of a yellowish liquid1 in which very numerous red blood-corpuscles or globules 7,pl4 ,,ix4 fig4 #a7 are suspended1 and to which the red colour is owing4 ,the blood-corpuscles are not globular1 but discoidal1 i4 e4 they are circular and flattened1 the sides being slightly sunk in4 ,their form is best seen as they roll over on a slide1 after the application of a glass cover4 ,the coloured corpuscles are cells2 they appear yellowish red under the microscope1 the deep red colour of the blood depending upon the large number of them seen at once and crowded together4 ,it need scarcely be stated that a drop of blood may easily be obtained1 by puncturing the wrist with a clean needle4 ,the blood is contained in the blood-vessels4 ,these consist of the arteries1 which convey the blood from the heart2 the veins1 which return it to the heart2 and a very fine set of intermediate vessels1 called the capillaries4 ,if a little water be added to a drop of blood on a slide1 colourless corpuscles1 rather larger than the coloured disks1 will be seen scattered among the latter4 ,these are the colourless or lymph-corpuscles of the blood4 ,they are truly spherical1 and granular on the surface4 ,bone4--,in examining a transverse section of a bone1 one or several very large cavities will be seen with the naked eye in the centre of the section2 these contain the marrow1 or medulla4 ,in the long bones1 the medullary cavity is single1 and runs longitudinally down the bone2 whilst in the flat bones the cavities are numerous1 forming cancelli4 ,under the microscope1 thin transverse sections of bone exhibit oval or rounded holes1 or foramina 7,pl4 ,,ix4 fig4 #ae71 which are sections of canals conveying blood-vessels through the bone2 these are the ,haversian canals4 ,around the sections of these canals are seen numerous concentric rings1 indicating layers or lamell of bony matter4 ,the substance of bone presents numerous black1 somewhat elongated bodies 7fig4 #ae a71 called the lacn 7lacna1 a little hollow7 or bone-corpuscles1 which are however hollow1 therefore not truly corpuscles1 as they were formerly considered4 ,between the adjacent lacun run numerous fine1 dark1 branched lines1 consisting of very minute canals1 or canaliculi4 ,if the section of bone be viewed by reflected light1 the lacun and canaliculi will appear white4 ,in the dried bone they contain air4 ,the structure of bone is best seen when viewed as a transparent object in the dry state2 for when the section is immersed in liquid1 the lacun and canaliculi become filled up4 ,the size and form of the bone-corpuscles and canaliculi vary in different animals1 so much so that the ,class or ,order to which an animal belongs may be determined by reference to these particulars4 ,bone consists of earthy salts deposited in a finely granular form throughout the substance of cartilage4 ,by soaking a piece of bone in vinegar or other dilute acid1 the earthy salts will be dissolved1 the soft cartilage being left4 ,but the structure of cartilage may be best observed by making thin sections of the gristle covering the ends of bones4 ,it exhibits a bluish-white basis 7,pl4 ,,ix4 fig4 #af71 in which are imbedded numerous cells or cartilage-corpuscles1 often undergoing cell-division4 ,in some kinds of cartilage1 the basis is composed of fibres4 ,muscle4--,on examining a piece of the red flesh of an animal under a low power1 the mass will exhibit a number of coarse1 parallel1 longitudinal1 dark lines 7,pl4 ,,ix4 fig4 #bj71 the substance between these lines being marked with cross or transverse stri1 or lines1 and with fine longitudinal lines4 ,the coarse longitudinal lines indicate the intervals between bundles of slender fibres1 or fibrill1 of which muscle consists4 ,the fibrill 7fig4 #bj b1 c7 are very difficult to separate2 but when perfectly separated1 they are seen to be exceedingly slender1 and to consist of alternately light and dark portions in regular series4 ,when the fibrill of the bundles are in close apposition1 as in the natural muscle1 the dark portions1 being in the same lines1 by their coincidence form the transverse stri4 ,the bundles into which they are combined are surrounded by a delicate skin or membrane1 with a little cellular tissue4 ,the structure of muscle may be observed in a piece of ham which has been soaked for a day or two in spirit of wine1 the mounted needles being used to pick it to pieces4 ,the above-mentioned transversely striated muscular fibre is that found in the voluntary muscles1 or those under the influence of the will4 ,but there are other muscles in animals which are involuntary1 or not subject to the will2 in these the fibrillar structure is absent1 the muscular tissue consisting of simple elongated and nucleated cells4 ,cellular tissue4--,this fills the interstices between the other tissues and organs of animals1 in the same manner that the vegetable parenchyma does those of plants4 ,it is not1 however1 composed of cells1 but of very fine1 soft1 colourless1 and wavy fibres 7,pl4 ,,viii4 fig4 #bj a71 aggregated into bundles1 which interlace so as to leave spaces or arol between them4 ,the cellular or areolar tissue may be found in a piece of beef or mutton1 in the intervals of the muscular fibres4 ,skin4--,the skin is composed of cellular tissue1 its outer surface presenting a number of projecting blunt points1 called papill4 ,it contains a large number of blood-vessels2 and when the capillaries are well filled by injection with a coloured composition1 it forms a beautiful microscopic object4 ,the skin is covered by the epidermis or cuticle1 which consists of several layers of cells4 ,it is the epidermis which is raised and covers the bladders formed by the action of a blister applied to the skin4 ,hair4--,the hair consists of long solid filaments 7,pl4 ,,ix4 fig4 #i71 and not of hollow tubes1 as was formerly supposed4 ,it presents varieties of structure in different animals1 which agree generally in animals belonging to the same ,orders4 ,hairs are implanted in pits in the skin2 each is swollen at the base to form the bulb1 which is seated upon a papilla of the skin1 by which it is formed or secreted4 ,the hair is an epidermic formation1 consisting of epidermic cells more or less flattened and altered in shape by mutual pressure4 ,the colour of the hair is usually seated in the outer or cortical portion of the stem or shaft1 and arises from the presence of aggregations of minute granules of colouring-matter or pigment1 as the colouring-matter of animals is called3 in the human hair it forms short longitudinal stripes 7fig4 #i74 ,in the central pith or medullary portion of the hair the cellular structure is more open and distinct than in the cortical portion1 in which the cells are so compressed and consolidated as only to exhibit the cell-structure after treatment with reagents2 and the medullary cells often contain air4 ,in grey or white hairs1 the whiteness depends mainly upon the presence of air in the cells of the pith4 ,in the gnawing or rodent animals1 as the mouse or the rabbit1 the pigment is partially at least situated in the cells of the medulla4 ,in the hairs of many animals1 the cuticular or surface-cells of the shaft are distinctly imbricated 7fig4 #e71 and form beautiful microscopic objects4 ,the principal interest in the structure of the hair relates to the three points above mentioned1 viz4 the position of the pigment1 the arrangement of the cuticular cells or scales1 and that of the cells of the pith4 ,the pigment is best examined in hairs moistened with a little spirit of wine1 which displaces the air from the cells of the pith1 and renders the hair transparent2 a little water should be subsequently added4 ,the cuticular scales are also well shown by this proceeding4 ,towards the root of the hairs in the mouse1 they project beyond the margin1 giving it a toothed or dentate appearance2 in the hair of the mole1 the bat 7fig4 #e71 or the wolf1 this dentation may also be seen4 ,in the hairs of some of the foreign bats1 the scales are whorled1 forming very beautiful objects4 ,the cells of the pith 7,pl4 ,,ix4 fig4 #g7 also present interesting varieties1 being sometimes arranged in a single row1 at others in two or more rows 7fig4 #f74 ,these are best seen in hairs recently immersed in spirit or in oil of turpentine2 for if the hair be too long soaked in these liquids1 the air will be entirely displaced by them4 ,the cells of the pith appear black by transmitted and white by reflected light1 in the dry hairs1 from the presence of air4 ,they may be well examined in the hair of the mouse 7figs4 #f #g71 or in that of the mole4 ,wool1 which is the hair of the sheep1 consists of curled fibres 7,pl4 ,,ix4 fig4 #aj71 in which the imbricated arrangement of the surface-scales is very distinctly seen4 ,in ,pl4 ,,ix4 figs4 #aj-ac the fibres of wool1 flax or woody fibre1 cotton1 and silk are represented together1 to allow of comparison2 for the microscope is of great assistance in discriminating these substances when existing in textile fabrics4 ,the fibres of wool 7fig4 #aj7 are distinguished by their solidity1 wavyness1 and the imbricated scales2 those of flax 7fig4 #aa7 by their thick walls1 great length1 acute ends1 and their knotty appearance at intervals4 ,the fibres of cotton 7fig4 #ab7 are soft1 flaccid1 flattened1 and often twisted2 and those of silk 7fig4 #ac7 are solid and very slender4 ,by a little chemical testing1 the discrimination is made still more easy2 but for an account of this ,i must refer to the ,dictionary4 ,,birds4--,in the ,class of ,birds1 the structure of the feathers deserves special notice4 ,feathers are epidermic formations1 or consist of aggregations of epidermic cells1 yet so altered by compression and fusion together that the cell-structure is in most parts difficult to detect4 ,in a feather three parts are distinguishable1--the transparent cylindrical quill2 its opake continuation1 which is more or less flattened at the sides1 forming the shaft2 and the vanes or beards1 which arise from the sides of the shaft1 consisting of numerous closely set1 parallel1 flattened fibres1 called the barbs4 ,the structure of the barbs forms the interesting object to the microscopist4 ,on examining a piece of the coloured vane of a somewhat large feather 7,pl4 ,,ix4 fig4 #ad71 a row of fine parallel colourless filaments 7pinn7 will be observed1 arising from the opposite sides1 the filaments of one side lying obliquely across those arising from the other2 and while the filaments or pinn of one side present a row of little teeth 7fig4 #ad c7 near their base1 those of the opposite side 7fig4 #ad b7 are provided with as many hooks near their apex1 which curve over the teeth to connect the barbs together4 ,this curious arrangement is adapted to keep the parts of the feather firmly united1 and yet to allow of their play and flexibility4 ,to observe this structure1 a portion of a vane should be soaked in oil of turpentine1 and mounted in balsam4 ,in the downy feathers 7,pl4 ,,ix4 fig4 #ag7 the barbs are not furnished with the pinn1 but present simply whorls of minute spines 7fig4 #ah74 ,the bones of birds present the same general structure as that of mammals1 the lacun being1 however1 more numerous and smaller4 ,the blood of birds 7,pl4 ,,ix4 fig4 #b7 differs entirely from that of mammals1 in the red corpuscles being oval instead of circular1 and convex instead of concave2 and each contains a distinct oval and granular nucleus4 ,,reptiles4--,in reptiles1 as the frog1 toad1 or water-lizard 7,trton71 the bone-corpuscles or lacun are larger and more numerous than in either of the former classes2 and the blood-corpuscles 7,pl4 ,,ix4 fig4 #c7 are comparatively very large1 oval1 rather concave1 and contain a large granular nucleus4 ,the smooth water-newt or triton1 properly called ,lissotrton puncttus1 is a very interesting animal in a microscopic point of view4 ,it may be found in most ponds2 and if several are removed in a net1 and kept in a large glass jar1 with water-plants1 they will live for a long period4 ,in the spring or early summer they will deposit their eggs upon the aquatic plants1 generally on the under surface of a leaf1 which they bend downwards1 so as to protect them4 ,the eggs or ova1 are about half the size of a pea1 and consist of a sac containing a transparent liquid1 with a yellowish globule within4 ,after a time these eggs will hatch1 and the larv or young newts must be removed from the water1 otherwise the parents will devour them4 ,if one of these larv1 which resemble little fish in appearance1 be placed with a little water in the 8live-box10 and the cap be very gently pressed down1 so as to fix the body of the animal1 the circulation of the blood may be very beautifully seen in either the fringe-like gills1 which are placed on each side of the neck1 or in the tail1 a low power being used2 at the same time the beautiful stellate pigment-cells of the skin will be observed4 ,the structure of the rudimentary spinal column1 which runs down the middle of the back1 and consists of simple large cartilage-cells1 may also be made out1 when the animal is dead1 by a little dissection with the aid of needles4 ,,fishes4--,in the fourth class of vertebrate animals1 which consists of the fishes1 we find interesting structures in the blood1 the scales1 and the roe4 ,the corpuscles of the blood 7,pl4 ,,ix4 fig4 #d7 differ from those of the ,mammalia1 but agree with those of birds and reptiles1 in being oval instead of round4 ,the scales of fishes 7,pl4 ,,ix4 figs4 #bb1 #bc7 are usually rounded or oval1 as in most of our freshwater fishes1 when they are called cycloid 71 circle72 but sometimes they are toothed at one end 7fig4 #bc a71 forming ctnoid 71 a comb7 scales1 as in the perch4 ,most scales exhibit a number of concentric rings1 which are the indications of lamin2 and many of them are lobed at the margin1 sometimes also having radiate furrows4 ,in the centre are often seen little rounded solid bodies1 having somewhat the appearance of cells1 which are very well seen in the scales of the perch2 and in some scales these bodies are arranged in concentric rows throughout the substance1 as in those of the eel or the cod 7fig4 #bd74 ,the substance of which scales consist is generally cartilaginous2 in some of them1 however1 true bony matter is present4 ,fish-scales are contained within the substance of the skin1 and not merely attached to it by one end1 as appears to be the case in many fishes4 ,in most of our common fishes1 as the roach or perch1 the scales project beyond the level of the skin2 but the projecting portion is covered by a thin layer of the skin2 and when the scales are scraped off1 this layer1 with its elegant stellate pigment-cells1 is usually found adherent to it4 ,in some other fishes1 as the cod and eel1 the scales are entirely sunk below the surface2 and these are commonly supposed to have no scales4 ,they may1 however1 be easily found by dissection1 or by drying a piece of the skin under pressure between two plates of glass1 and mounting a portion in balsam4 ,the beautiful silvery lustre of the skin of fishes depends upon the presence of innumerable very minute and thin crystals2 these may be well examined in the skin of a sprat4 ,the roe of fishes consists of the ova or eggs1 and the spermatozoa1--the ova being contained in the hard1 the spermatozoa in the soft roe4 ,the eggs consist of a cell surrounded by one or two membranes2 and the latter are often traversed by numerous fine radial canals1 or present a funnel-shaped tube leading to the ovum4 ,the spermatozoa of the soft roe consist of exceedingly slender filaments 7fig4 #be71 terminated at one end by a kind of head4 ,the reader will not fail to detect the analogy between the ovum of the animal and that of the ovule of the plant2 and it need scarcely be stated that the spermatozoa of the animal fertilize the ova1 in the same manner that the pollen-tubes and spermatozoa of plants fertilize the ovules existing in them4 ,in the case of fishes1 the spermatozoa of the soft roe escaping into the water1 and moved by the ciliary action of the filament1 enter the micropyle-like canals of the ova1 which are deposited by the fish upon the bottom of rivers4 ,the scales of fishes may be prepared for examination by scraping them off and macerating them in water until the adherent portion of the skin is softened and decomposed1 so that it may be washed away4 ,they should be dried between glass plates1 and viewed under a low power1 as dry transparent objects4 ,the structure of muscle can be more easily made out in fishes than in other animals4 ,a portion of the flesh should be macerated in spirit as directed above4 ,,mollus,,ca4--,we shall now leave the vertebrate animals1 and pass to the subkingdom ,mollusca1 the marine kinds of which are popularly called shellfish3 three of their structures form interesting objects for examination--the shell1 the tongue1 and the gills4 ,shell4--,the general structure of the shell of the ,mollusca may be illustrated by reference to that of the oyster4 ,two kinds of shell-substance are at once distinguishable in an oyster-shell1 an outer brown1 and an inner pearly or nacreous4 ,the brown portion exhibits under the microscope the appearance of a cell-structure 7,pl4 ,,ix4 fig4 #bh71 the angular forms from mutual pressure being very distinct4 ,the component bodies of this portion are seen to be more or less elongated and flattened in the side view1 forming prisms 7fig4 #bi74 ,the structure of the pearly part of the shell is more difficult of examination1 and can only be seen distinctly in ground and polished sections4 ,in these1 under a high power1 it exhibits numerous fine1 somewhat parallel wavy lines 7fig4 #ai71 which are the indications of thin layers1 or lamin1 of which it is composed4 ,shell consists of a basis of animal matter in which carbonate of lime 7chalk7 is deposited1 the whole being poured out or secreted by the skin or mantle of the mollusk4 ,pearls1 which possess the same structure as the nacreous part of shell1 consist of the nacre formed around some foreign body1 as a grain of sand1 c41 by which the mantle has been wounded4 ,tongue4--,the structure of the tongue of the ,mollusca is very interesting1 on account of the curious teeth which are found upon it4 ,it may be illustrated by the common ,whelk 7,buccinum undatum71 which is sold at the street-stalls4 ,as1 to one unacquainted with the anatomy of the ,mollusca1 there is some difficulty in finding the tongue1 it may be well to point out how it is to be found4 ,if the shell containing the animal be placed so that its orifice is directed upwards1 the point or apex of the spire being towards the reader1 the lid 7operculum7 which closes the shell will be at once evident4 ,on drawing the animal from the shell by means of the lid1 the foot or portion which is applied by the animal to the surface upon which it creeps will be seen4 ,at the upper part of this is the head1 with its two horns 7tentacles74 ,below the roots or bases of the tentacles1 and between them and the upper part of the foot1 is the little round mouth4 ,on slitting this up with scissors1 a cavity will be opened1 and in it will be seen a reddish tube 7the proboscis71 about as large as a goose-quill1 with an aperture at the end4 ,this must be carefully slit up1 when the tongue1 which is of about the size of a crow-quill1 will come into view4 ,the tongue is moveable in the proboscis1 and can be protruded or withdrawn by the animal at will4 ,if the surface of the tongue be viewed under a handlens1 the rows of teeth will be seen at once4 ,it is better not to pull the tongue out with forceps1 as the teeth are easily displaced and injured4 ,the best plan is to dissect away the muscular structures with forceps and a pair of fine-pointed scissors1 then to cut off the tongue at its root1 and to soak it in water for some hours1 when the skin or epidermis containing the teeth can be separated with the mounted needles under a simple lens or microscope4 ,after any loose particles have been washed away with a hair pencil1 the object may be spread flat on a slide1 and dried between two slides4 ,the upper slide should then be removed1 the tongue soaked in oil of turpentine1 and mounted in balsam with the least possible heat4 ,as thus prepared1 the horny teeth 7,pl4 ,,ix4 fig4 #ba7 are seen to be arranged in rows1 united by a colourless membrane1 so as to form a long ribbon4 ,the teeth form three longitudinal parallel rows1 a central and two lateral4 ,each tooth1 considering the separate pieces as constituting distinct teeth1 has little teeth or denticles at its lower edge4 ,these are curved inwards1 four in number1 and connected by a basal plate in the side teeth2 while the middle teeth have six or seven straight denticles4 ,these teeth serve to enable the animal to scrape or rasp the alg1 and other matters forming their food1 from the surfaces upon which they grow4 ,and if some water-snails are placed in a glass jar the inside of which is covered with confervoid growths1 the curious patterns left after the action of the snails' tongues will be found to present a very curious appearance4 ,gills4--,the gills or 8beards0 of the oyster or mussel exhibit very strikingly the phenomenon of ciliary motion4 ,the gills 7branchi7 are respiratory organs1 consisting of folds of the skin1 covered with cilia1 by means of which the water in which the animal lives is set in motion1 and constantly changed to arate the blood within them4 ,the currents thus induced serve also to bring the food which floats in the water towards the mouth of the animal4 ,by snipping off a thin portion of one of the brown beards of a fresh oyster1 laying it upon a slide1 adding a drop of the 8liquor0 contained within the shell1 and lightly pressing a cover upon the whole1 the remarkable phenomenon to one who has not before viewed it will be seen under a somewhat high power--about -inch4 ,the whole field will appear in motion1 and the lashing or whip-like action of the cilia will be seen1 especially towards the edges of the bars 7,pl4 ,,ix4 fig4 #cf7 of the gills4 ,the rapid motion of any floating particles present will also be noticed1 showing the direction of the currents of liquid1 which1 as the liquid is transparent1 would not otherwise be recognizable4 ,,bryoz,a 71 moss1 1 animal74--,the animals included in this ,class1 which belongs to the ,mollusca1 are mostly marine4 ,they are microscopic1 and contained in horny or calcareous sacs or cells1 aggregated together to form polypidoms 7polype1 and 1 a house74 ,they are sometimes plant-like or leafy 7,pl4 ,,ix4 fig4 #bg71 at others filamentous and branched1 or they form a layer or crust upon the objects to which they are attached4 ,the polypidoms1 which are often some inches in length1 are frequently met with on the seashore1 the cells 7fig4 #bf a7 having slit-like valvular orifices4 ,the bodies of the animals are soft and polype-like1 and are furnished at one end with a circle of tentacles1 covered with rows of cilia1 by which the water is changed for respiration1 and particles of food are brought to the mouth4 ,the tentacles can be protruded or withdrawn at the will of the animal4 ,the ,bryozoa are what are called compound animals1 each individual body having its own set of organs2 yet the whole are connected together4 ,the two species figured are very common4 ,flustra folicea 7,pl4 ,,ix4 fig4 #bg7 is found everywhere upon the sea-shore4 ,the polypidom has cells upon both sides2 and they are narrowed at one end1 and rounded at the other4 ,membranipora pilsa 7,pl4 ,,ix4 fig4 #ci7 occurs upon sea-weeds and other marine bodies1 forming a closely adherent layer4 ,the orifices of the cells are surrounded with teeth1 and are usually furnished below with a very long bristle--the polypidom appearing to the naked eye as a white hairy crust4 ,in the variety figured1 the long bristles are replaced by a spine2 and this is not uncommon4 ,the polypidoms of the ,bryozoa form interesting microscopic objects1 the cells being furnished with variously arranged spines and punctures or dots4 ,in some the cells are erect and arranged in rows upon the branches of a plant-like stem1 while in others they are scattered irregularly over a creeping filament4 ,for examination they should be prepared by maceration in fresh water1 and drying between glass plates or sheets of paper1 and either viewed as opake objects or1 after soaking in turpentine and mounting in balsam1 as transparent objects4 ,it may be remarked that the name ,bryozoa for this class of ,mollusca1 which was thoroughly established1 has recently been changed in this country to ,polyza 71 many1 1 animal71 and that the name of polypidom has been altered to polyzary4 ,,chapter ,,xi4 ,,articulata 7,,artic,,ulus1 ,a ,,joint74 ,the animals belonging to this subkingdom are specially distinguished by the body and limbs being jointed3 as familiar instances1 may be mentioned the lobster1 the wood-louse1 spiders1 insects1 and worms4 ,taking the class ,crustacea1 to which the two first animals belong1 we find interesting microscopic forms in the subclass ,entomostraca 71 insect2 1 shell74 ,,entomostraca4--,the animals contained in this ,order are met with in every pool or pond1 some of them inhabiting the sea4 ,they are mostly minute1 yet visible to the naked eye1 forming specks swimming actively or leaping through the water2 hence some of them have been called water-fleas4 ,the body of the animal is protected by a shell or carapace1 which in some consists of a single piece 7,pl4 ,,ix4 fig4 #cj71 while in others it consists of two similar parts or valves 7fig4 #ca71 in the latter case the joints of the body being indistinctly visible4 ,the head is furnished with usually two projecting feelers or antenn 7antenna1 a sail-yard71 one of which is uppermost or superior 7,pl4 ,,ix4 figs4 #cj1 #ca1 #cd a71 the other lowermost or inferior 7figs4 #cj and #cd b72 and these are often used for swimming4 ,the antenn are jointed1 and sometimes beautifully plmose 7pluma1 a feather7 or feathery1 i4 e4 furnished with rows of long and very slender filaments4 ,there are several pairs of jointed legs1 some of which serve as jaws 7foot-jaws71 while others are finely filamentous to serve for swimming and as respiratory organs 7branchial feet74 ,the four species figured are very common4 ,cypris tristrita 7,pl4 ,,ix4 fig4 #cd7 is found in ponds and ditches4 ,the carapace is bivalve1 or has two valves1 which are convex and oval2 and it is of a greenish colour1 with three irregular dark stripes behind4 ,the superior antenn 7a7 are jointed and finely feathery1 the inferior antenn 7b7 having a tuft or pencil of fine filaments arising from their anterior margin4 ,the eye is single4 ,the animal swims steadily and freely through the water4 ,the eggs of ,cypris 7,pl4 ,,ix4 fig4 #ce7 are often found in glasses of water containing the animals4 ,they are rounded or oblong1 of a red colour1 glued together by an amorphous jelly1 and adherent to pieces of stick or the sides of the glass4 ,they are enclosed in a thick shell1 which exhibits a cellular appearance in the surface view1 and is striated in the side view2 so that the structure of the shell is prismatic1 as in that of the oyster4 ,when the eggs escape from the shell1 they present the appearance represented in fig4 #ce a1 the body of the young animal being enclosed in a transparent envelope1 one end of which forms a blunt protrusion2 there is also a separate slender process enclosing the superior antenn4 ,after a time1 the envelope is cast off 7fig4 #ce b71 when the animal begins its active stage of life4 ,the cast-off envelopes 7fig4 #ce c71 with the protruded portions wrinkled1 are often found in the sediment of water containing the animals4 ,the structure of these ova is that of what are called winter ova1 which agree with the resting-spores of the lower plants or the ,alg4 ,cyclops quadricornis 7,pl4 ,,ix4 fig4 #cj7 is another common species4 ,in this the body is closely surrounded by the jointed shell1 as in a lobster4 ,the superior antenn 7a7 are very long and many-jointed1 each joint having short bristles arising from it1 while the inferior antenn are short and four-jointed4 ,there is no separate head1 this being united to or consolidated with the first joint of the thorax or chest1 the head and thorax together comprising four joints4 ,the remaining joints enclose the belly1 or abdmen1 which has the appearance of a tail2 but the tail is constituted by the two last parallel pieces1 which are furnished with fine feathery filaments4 ,the female is most commonly met with1 and is easily known by having the egg-pouch1 or ovary 7o7 external on each side1 and filled with eggs or ova4 ,the little ,cyclops is readily recognized by its form and jerking motion through the water4 ,daphnia plex 7,pl4 ,,ix4 fig4 #ca7 is a very common ,entomostracan1 and is very well adapted to illustrate the structure1 on account of its size and transparence4 ,in this animal the body is loosely connected with a bivalve shell1 which1 on careful examination1 is seen to be reticulated or marked with net-like lines4 ,the superior antenn 7a7 are very small1 placed under a small beak1 and have at the end a minute tuft of hairs4 ,the inferior antenn 7b7 resemble arms1 being large and branched2 and by means of them the animal rows itself through the water4 ,the structure of the eye is curious1 consisting of a number of round lenses aggregated together1 the fine muscular threads by which it is moved being easily distinguished with a high power4 ,the legs are flattened1 and furnished with elegant feathery st 7seta1 a bristle71 serving as gills or branchi4 ,they are constantly in motion1 fanning the water so as to change incessantly the portion with which they are in contact4 ,about the middle of the back is placed the little transparent heart1 with its colourless blood1 which may be distinctly seen beating1 or contracting and dilating1 in the living animal2 and between the back of the animal and the shell are seen the ova1 which remain there until they are hatched4 ,the genera and species of the ,entomostraca are very numerous4 ,those mentioned above will serve to illustrate the general structure of the order4 ,to distinguish the mandibles 7mandibula1 a jaw7 or proper jaws1 the foot-jaws1 and the branchial legs1 the animals must be dissected in water with the mounted needles4 ,the very delicate feathery filaments of the branchi may be best observed when these organs are dried on a slide4 ,the ,entromostaca may be kept alive in a jar of water with water-plants for a long period4 ,they may be removed from the water for examination by the dipping-tube1 and are best observed in a live-box4 ,,arach,,nida 71 spider7 is the ,class of spiders1 scorpions1 and mites4 ,aranida4--,this ,order contains the more highly developed forms of the ,class1 among which are the common spiders of houses and gardens2 and some of their structures are very curious and interesting4 ,the head of spiders is united or fused with the thorax1 forming one piece1 which is called the cephalothorax 71 head1 1 chest74 ,the claw-jaws1 or mandibles1 are terminated by a curved and pointed claw1 with which the spiders hold their prey4 ,it is traversed by a slender canal1 containing a slender tube or duct leading from a poison-gland1 and opening near its point2 and when the insect prey is transfixed by the mandible1 the poison is pressed out and enters the wound4 ,near the root or base of the mandibles on each side is a jointed feeler1 or palpus2 but spiders have no antenn4 ,the eyes are simple1 forming separate round shining dots1 and are called ocelli 7ocellus1 a little eye72 they are usually placed on the top of the head1 and are often arranged in a geometrical form1 as a triangle1 c4 ,the legs are four pairs2 they are hairy1 and terminated by two or three claws1 which are fringed with minute teeth1 or pectinate4 ,these claws serve to comb the fibres of the web1 just as we comb our hair with a common comb4 ,the spinnerets1 with which spiders form their web1 are very curious organs4 ,they are situated at the under and hind part of the body1 and consist of two or three cones1 or papill1 on each side4 ,on the summits of these papill are very numerous bristle-like tubes1 through which the secretion of certain glands passes2 this secretion1 when hardened by exposure to the air1 forms the fibres of the web4 ,on carefully examining a spider's web1 the radial fibres1 or those which pass from the centre to the circumference1 will be found to be smooth1 these fibres serve to fix the web2 while the cross fibres are covered with numerous viscid globules1 which serve to attach flies or other prey to them4 ,this difference of the fibres is best observed with a hand-lens4 ,,acar,,na1 or the ,order of ,mites4--,here belongs cheese-mite1 ,acarus domesticus 7,pl4 ,,ix4 fig4 #cf74 ,its body is somewhat milky white1 oval1 and furnished with feathery hairs4 ,when viewed from beneath1 there is seen a transverse line1 indicating the separation of the thorax from the abdomen2 and another line in front of this1 with four minute tubercles1 from each of which arises a hair4 ,the head is pointed and beak-like1 forming a rostrum 7rostrum1 a beak71 consisting of two mandibles pressed together2 these can only be seen to be separate when dissected apart with the mounted needles4 ,each mandible is chlate 71 forceps71 or has the form of a lobster's claw2 and beneath the two mandibles is a flat membranous under lip or labium1 consolidated on each side with a palp4 ,the legs are four pairs1 as in all the ,arachnida2 they are pinkish1 #f-;jointed1 and terminated by a leaflike sucker and a minute claw4 ,the males 7fig4 #ch7 are smaller than the females1 the fore legs being much stouter1 and furnished with a blunt tooth 7fig4 #ch a74 ,the eggs can often be distinguished within the body of the female 7fig4 #cf72 they are oval and granular4 ,another species of ,acarus1 ,a4 sacchari1 is found abundantly in ordinary moist sugar4 ,if a little of the sugar be placed in a wine-glass1 some water added1 and the mixture be stirred until the sugar is dissolved1 the ,acari will be found both in the sediment and floating on the surface4 ,a somewhat larger member of the order occurs as a parasite upon a species of ,dung-beetle 7,geotrpes stercorrius7 which is vulgarly known as the ,lousy ,watchman4 ,the beetle is black1 shaded with purple1 about three-quarters of an inch long1 and is found under cow-dung4 ,the mites cling pertinaciously to the under parts of the beetle1 and can easily be seen with the naked eye4 ,they are whitish1 with the mandibles1 the sucker1 and two claws very distinct2 and the palpi are unattached to the labium1 or free4 ,these mites form the species ,gamasus coleoptratorum4 ,another species1 ,gamasus telrius1 is the red spider of the greenhouse4 ,trombidium fuliginsum 7,pl4 ,,ix4 fig4 #cg d7 is a common red spider of gardens4 ,it is of a scarlet colour1 appearing velvety from the presence of a dense coat of feathery hairs 7fig4 #cg f74 ,the palpi of this mite are large1 free1 the last joint but one 7,pl4 ,,ix4 fig4 #cg a7 being furnished with a claw1 while the last joint is obtuse1 and resembles a lateral appendage4 ,the mandibles 7fig4 #cg b7 are furnished with a sharp curved claw4 ,the legs are long1 especially the anterior pair1 and terminated by two claws1 with a delicate sucker-like appendage 7fig4 #cg c74 ,another species of ,trombidium1 ,t4 holosericeum1 greatly resembling the last1 is also found in gardens4 ,it may be easily distinguished from the last by the club-shaped hairs 7fig4 #cg e7 existing upon the body4 ,the harvest-bug1 which causes such irritation of the legs of persons who frequent corn-fields in the autumn1 is also a species of ,trombidium--,t4 autumnle4 ,,plate ,x4 page #acc4 ,,insects4 ,fig4 #a4 ,atropos pulsotorius3 99 natural size4 #b4 ,aphis of ,geranium3 a1 foot2 b1 anal tube2 c1 antenna4 #c4 ,scales on wing of ,apollo-butterfly4 #d4 ,lithobius forcipatus4 #e4 ,lithobius forcipatus1 head of3 a1 antenn2 b1 mandibles2 c1 labial palpi2 d1 labium4 #f4 ,dytiscus marginalis1 head of larva4 #g4 ,young larva of ,dytiscus marginalis4 #h4 ,pupa of ,gnat 7,culex pipiens74 #i4 ,larva of ,gnat4 #aj4 ,head of ,gnat1 male4 #aa4 ,head of ,gnat1 female4 #ab4 ,coccinella #g-punctata 7large ,lady-bird71 labium of4 #ac4 ,coccinella #g-punctata1 mandible of4 #ad4 ,coccinella #g-punctata1 labrum of4 #ae4 ,coccinella #g-punctata1 antenna of4 #af4 ,coccinella #g-punctata1 maxilla of3 a1 palp2 b1 c1 lobes of maxilla4 #ag4 ,head of ,musca domestica 7,house-fly73 a1 antenna2 b1 labial palpi2 c1 proboscis4 #ah4 ,head of ,stomoxys calcitrans3 #ah a1 antenna4 #ai4 ,scales of insects3 a1 scale of ,podura2 b1 of ,house-moth 7,tinea vestianella72 c1 of ,podura2 d1 of ,lepisma2 e1 hair of ,podura2 f1 scale of ,cabbage-,butterfly 7,pontia brassic74 #bj4 ,head of ,cabbage-,butterfly3 a1 antenn broken off2 b1 palp2 c1 tongue 7antlia72 d1 club of antenna4 #ba4 ,head of human ,flea 7,pulex irritans71 female 773 a1 palpi2 b1 maxill4 #bb4 ,flea of the ,rat 7,pulex muris71 male 774 #bc4 ,pterostichus 7,steropus7 madidus2 #bc a1 antenna4 #bd4 ,part of leg of ,pterostichus madidus3 a1 tibia2 b1 tarsus4 #be4 ,labrum of ,pterostichus madidus4 #bf4 ,mandible of ,pterostichus madidus4 #bg4 ,labium of ,pterostichus madidus3 a1 mentum2 b1 labial palp4 #bh4 ,maxilla of ,pterostichus madidus3 a1 claw2 b1 c1 maxillary palps4 #bi4 ,proboscis of ,house-fly4 #cj4 ,larva of ,flea4 #ca4 ,larva of ,chironomos plumosus4 #cb4 ,foot of ,house-fly4 #cc4 ,eye of ,house-fly4 #cd4 ,leg of ,ant 7,formica fusca72 #cd991 pectinate process4 ,illustration3 ,plate ,x4 ,w ,bagg sculp ,london3 ,john ,van ,voorst4 ,preparation4--,the organs of the mouth1 c41 of the ,spiders are easily prepared for examination1 by carefully pulling them off with forceps or the mounted needles1 then drying them under pressure between two glass slips1 macerating in turpentine1 and mounting in balsam4 ,those of the ,acarina should be dissected out with the needles1 after the body has been crushed in a drop of water on a slide1 and the internal substance has been gently washed away with a hair pencil4 ,they may then be dried on a slide1 with a cover laid on1 and turpentine applied to the edge of the cover1 balsam being added when most of this has evaporated4 ,the various parts may also be mounted in chloride of calcium or glycerine4 ,,insects4--,the members of the class of ,insects are extremely interesting to the microscopic observer1 not only on account of the beautiful structures which they present1 but also from these being comparatively large1 usually coloured1 and easily distinguished under the lower powers4 ,hence they form admirable objects for study to those who are but little accustomed to the use of the microscope4 ,,myriap,,oda 71 myriad1 1 foot74--,this ,order contains those insects which are popularly known as the hundred-legs and millepedes2 by many zoologists they have been arranged in a distinct class4 ,the most common member of this ,order is ,lithbius forciptus 7,pl4 ,x4 fig4 #d71 which is found under stones1 in cellars1 and among garden-rubbish4 ,it is of a yellowish-brown colour1 with long1 many-jointed1 gradually tapering or setceous 7sta1 a bristle7 antenn 7figs4 #d a1 #e a71 and two large and powerful mandibles 7fig4 #e b7 resembling those of the spiders4 ,it has also a broad1 notched1 and toothed lower lip1 or labium 7fig4 #e d71 above which are two toothed jaws1 or maxill1 and two lip-feelers1 or labial palpi 7c74 ,the eyes consist of a group of ocelli on each side 7e74 ,the body is protected by alternately larger and smaller dorsal plates1 which are fifteen in number2 and there are fifteen pairs of legs1 which are terminated by a single claw4 ,on the sides of the body will be found some oval dark-looking bodies1 fringed with hairs2 these are the spiracles 7spiraculum1 a breathing-hole7 or breathing-pores4 ,they form the orifices of certain branched and transversely striated tubes1 which are distributed throughout the body2 the tubes are called trche 7trachea1 the windpipe71 and their walls contain an elastic spiral fibre which keeps them open4 ,these parts of the insect can only be distinctly seen when the body has been slit up on the under side2 and1 after washing away the animal matter with water by the aid of a hair pencil1 pressed between two slides with a clip1 dried1 soaked in turpentine1 and mounted in balsam4 ,,thysan,,ra 71 fringe1 1 tail74--,the insects belonging to the genus ,podra1 of this ,order1 are very minute and difficult to examine2 but they are specially interesting1 on account of the structure of their scales4 ,they are common in gardens and cellars1 under flower-pots1 c41 and are about one-tenth of an inch long4 ,they are of a brownish or silvery-leaden colour1 wingless1 with six legs1 and when touched they leap like a flea4 ,the leaping motion is produced by the action of the tail1 which is forked and bent under the body4 ,the body is usually covered with minute scales 7,pl4 ,x4 fig4 #ai1 a1 c71 and these are used as test-objects4 ,the structure of the scales varies in the different genera and species2 those usually used 7fig4 #ai a7 are stated to belong to ,podra plumbea2 it appears1 however1 that this is not correct4 ,the scales sold as test-objects under this name are covered with minute and short raised lines 7fig4 #ai a71 arranged in irregular but somewhat parallel wavy rows4 ,it requires a good microscope and a high power to show them distinctly1 and they should appear perfectly black and separate4 ,the little lines are much coarser in some scales than in others2 so that there are easy and difficult scales1 as they are called4 ,the ,podur may be caught by holding a sheet of paper near their haunts and disturbing them2 and when they have jumped upon the paper1 a slide laid upon them and gently pressed will remove some of the scales for examination4 ,the scales should be mounted as dry transparent objects2 for if wetted1 they become very transparent1 and the markings appear removed1 which however is not really the case4 ,the scales of ,lepisma saccharna 7,pl4 ,x4 fig4 #ai d71 a member of this ,order1 were formerly used as test-objects2 but they are too easily made out to serve for this purpose with modern microscopes4 ,the insect is not common4 ,the scales 7fig4 #ai d7 exhibit continuous nearly parallel longitudinal lines or ribs4 ,,anopl,,ra 71 unarmed1 1 tail74--,this third ,order of insects consists of the ,lice of the ,mammalia and birds4 ,they are minute1 resembling mites to the naked eye1 but may be at once distinguished from them by the distinct head and thorax and the presence of six instead of eight legs4 ,some of them are suctorial1 i4 e4 have a short and slender tube1 with which they suck the blood of the animals of which they are parasites2 while others are mandibulate1 or have mandibles1 and also maxill1 their food consisting of portions of feathers1 hairs1 and scurf4 ,the legs are usually short and stout1 and the claws large and powerful1 to enable them to hold firmly to the hairs1 c4 ,the ,anoplura are most abundant on dirty and diseased animals4 ,,suctor,,ia4--,the fourth ,order of insects consists of the genus ,plex1--,pulex irrtans being the human flea4 ,other species are found upon different animals1 as upon the dog1 the rat 7,pl4 ,x4 fig4 #bb71 the fowl1 the pigeon1 c4 ,the head and the dark eye 7fig4 #ba1 head of the human flea7 are very evident4 ,the antenn or head-feelers are very minute and difficult to find1 being sunk in a little pit or fossa behind the eye2 they may1 however1 generally be recognized by the detection of the last joint1 which is pectinate or cut like a comb4 ,the body1 including the head1 consists of thirteen joints1 one for the head1 three for the chest or thorax1 and nine for the belly or abdmen1--it being understood that by 8joint0 is meant a segment1 and not the line of junction of two segments4 ,the indication of these joints is afforded by the horny integument1 which consists of a corresponding number of rings1 forming in fact the skeleton of the animal4 ,this in the flea1 as in all insects and other ,articulata1 is external or cutaneous 7ctis1 skin71 and consists of the hardened skin1 the peculiar animal substance of which it is composed being called chitine 71 tunic74 ,these chitinous rings overlap1 and are composed of a dorsal or upper1 and a ventral or lower half2 and near the middle of each is a row of hairs directed backwards4 ,along the sides of the body of the insect may be seen a row of dots2 these are the spiracles or orifices of the breathing-tubes 7trache74 ,the legs are many-jointed1 long1 furnished with numerous spines1 and terminated by two slightly curved claws1 each with a little blunt tooth at its base4 ,the claws are not perfectly smooth on the inside1 but are covered with slightly raised lines1 like a file1 so that a better hold can be taken of bodies4 ,but the most interesting parts of the flea are those of the mouth1 with which it punctures the skin and sucks the blood4 ,there are nine of these2 and they are best seen when the head of the flea is pulled off with the mounted needles1 and the parts spread out and mounted in balsam1 a high power being used to examine them4 ,one of them forms a long and slender bristle 7seta7 or tongue1 furnished with distant minute teeth4 ,on each side of this is a flattened seta1 with two rows of teeth on the edges2 these are the lancets1 and when not in use these organs are inclosed in two jointed sheaths4 ,outside these are two representatives of jaws1 or maxill 7b71 each having a jointed feeler or palp 7a7 arising from it2 the probable use of the palps being to feel the position of the skin1 so that the animal may be able to adjust the lancets at a proper distance for puncture4 ,the eggs of the flea are often visible within the body of the parent2 and when this is crushed1 they are more distinctly seen1 of various sizes1 and contained within a long tube1 which is the ovary or egg-bag4 ,the eggs are laid by the animals upon carpets1 woollen garments1 or in the cracks of dirty floorboards2 they are just perceptible to the eye as white oblong specks1 and they may always be found on the rug when a cat is kept in the house4 ,when hatched1 they give rise to a minute white worm-like maggot1 or larva 7fig4 #cj71 having a #ab-;jointed body1 with two rudimentary antenn and two slightly curved hooks appended to the last joint4 ,the mouth-organs of the larva are adapted for biting1 and not for sucking1 as in the perfect animal1 the jaws or maxill being distinctly toothed4 ,when they have acquired full growth1 which takes place in about twelve days in warm weather1 they spin around themselves a little silky cocoon1 and become transformed into a chrysalis or pupa2 and from this1 in about a fortnight1 the perfect insect escapes4 ,,dip,,tera 71 twice1 1 wing74--,this1 which forms the fifth ,order of ,insects1 consists of the two-winged insects1 or flies1 as the house-fly1 the blue-bottle1 the gnats1 c4 ,,mus,,cid4--,the house-fly1 and the blue-bottle or meat-fly1 are both species of the genus ,musca1 belonging to this family1 the former being ,musca domestica1 the latter ,musca vomitoria4 ,both these insects are seen to be wonderfully constructed when minutely examined1 and they possess considerable resemblance in general structure4 ,on examining the head of the house-fly 7,pl4 ,x4 fig4 #ag7 under a low power1 and as an opake object1 the observer will be struck with the remarkable appearance presented by the two eyes1 which are large1 placed one on each side of the fore part of the head1 and composed of very numerous little eyes closely packed together1 or they are compound1 as it is called4 ,the use of this compound structure is evidently to enable the little animal to see in all directions without moving the head and eyes4 ,each little eye has a lens to bring the rays of light emanating from objects to a focus upon a nerve4 ,the packing of the eyes together gives rise to their angular form or their straight sides1 each of the little surfaces or facets being hexagonal1 or bounded by six sides 7fig4 #cc74 ,in front of and between the eyes are seen the two small antenn2 these have three joints1 the third of which is larger than the rest 7fig4 #ag a71 and arising from near its base is a feathery bristle or seta2 these structures are best seen when the antenn are pulled off with a pair of forceps and mounted separately4 ,below the antenn1 and extending downwards and forwards is the proboscis1 or tongue1 as it is called1 which can be entirely retracted within a pit in the fore part of the head1 or protruded at the will of the animal4 ,this is a very beautiful and complicated instrument1 and is best examined when spread out and separately mounted 7,pl4 ,x4 fig4 #bi74 ,it consists of a fleshy tube1 dilated at the end into two lobes1 which are flattened beneath to form a sucking-disk4 ,the end is furnished with two solid horny lateral branches to keep it expanded1 and with two longitudinal tubes beneath1 running parallel1 from the outer sides of which arise numerous nearly parallel branches4 ,these tubes and their branches are incomplete beneath1 and consist of imperfect rings1 otherwise greatly resembling trache4 ,on each side of the proboscis is a lip-feeler or labial palpus1 for the organ represents the labium of other insects4 ,all these parts are better seen in the proboscis of the blow-fly than in that of the house-fly1 on account of their larger size4 ,the head1 the thorax1 and the abdomen are very distinct in the fly1 being separated from each other by well-marked constrictions4 ,the legs are composed of five parts1 each having a separate name4 ,the first piece or joint1 which is that attached to the body1 is called the hip1 or coxa2 the next is a very small1 somewhat triangular piece1 and is the trochanter2 next comes the long and stout thigh1 or fmur2 this being succeeded by the tibia1 which1 as in most insects1 is furnished with strong spines at the end2 and lastly is the foot1 or tarsus1 consisting of five joints1 the three last of which are represented in the figure 7,pl4 ,x4 fig4 #cb74 ,at the end of the fifth or last joint of the tarsus 7fig4 #cb7 7for it must be noted that the joints of the limbs of insects are always numbered in order of distance from the body7 are two soft little cushions1 or pulvilli1 which are covered on the under surface with numerous hair-like bodies dilated at the end1 acting as suckers in enabling the fly to adhere to smooth surfaces4 ,in addition to these organs are two curved claws1 and between them a sharp straight spine4 ,the eggs of the fly are deposited upon heaps of decaying animal and vegetable matters1 as dungheaps1 c4 ,the blow-fly deposits its eggs in the same situations1 but especially those where the animal matters are most abundant3 every one knows the eggs as deposited upon tainted meats1 when they are called flyblows4 ,when the eggs are hatched1 the larv or maggots make their appearance4 ,the larv of the blow-fly are well known to the angler1 who uses them for bait1 and calls them gentles4 ,these larv exhibit some interesting points of structure4 ,the jointed or ringed condition of the body is distinct to the naked eye4 ,the head is provided with two rudimentary palpi1 placed each upon a rounded papilla2 also with two brown curved and horny hooks or jaws4 ,on the posterior end of the body are two brown spots1 which consist of spiracles1 and have three sieve-like oblong orifices2 and at the anterior margin of each segment of the body are very numerous little short spines1 with the points directed backwards4 ,these answer the purpose1 to some extent1 of legs2 for when the larva is moving1 and has forced itself through the matter in which it burrows1 the little spines prevent the body being forced backwards as the head is pushed forwards and meets any resistance4 ,to examine the structure of these larv1 the gentles should be killed by immersion for a time in warm water1 and then dried by touching them with blotting-paper4 ,the hooks and palpi can be seen by holding the body in the forceps as an opake object4 ,to observe the spiracles1 the end of the body should be cut off1 and the animal matter washed away in a watch-glass with water and a hair pencil1 then spread out1 dried between two slides1 and mounted in balsam4 ,the larv of the house-fly and of the blow-fly very closely resemble each other1 so much so that the former are generally overlooked2 hence it is often wondered where flies come from1 although they are so numerous in every house4 ,when the larv of these flies are fully developed1 they gradually assume a brown colour1 the organs of the head are retracted1 and the skin becomes dry and hard4 ,this is the state of pupa1 or chrysalis2 and while remaining in this state of rest1 the development of the wings1 legs1 c41 takes place2 so that when the insect emerges from the shell of the chrysalis1 it has attained its highest state of development1 and forms the imgo or perfect insect4 ,it may be remarked here1 that when insects pass through the three states of larva1 pupa1 and imago1 they are said to undergo complete metamorphosis4 ,there is not a more curious object than that presented by the young fly contained in its case1 as seen on carefully cutting away portions from one end of the case of the chrysalis4 ,the body and head are quite white1 with beautiful blood-red eyes4 ,most persons must have noticed another kind of house-fly1 having the wings more widely separated than in the common fly1 and moving more slowly through the air4 ,this is ,stomoxys calcitrans4 ,the proboscis of this fly 7,pl4 ,x4 fig4 #ah7 differs from that of the house-fly in being longer1 more bent1 and but little expanded at the end2 also in being provided with two long set1 one forming a slender sharp lancet1 the other being somewhat stouter1 and forming its sheath4 ,the fly is thus enabled to pierce the flesh and suck the blood4 ,,culic,,id4--,we will now say a few words about the gnats1 which are old favourites for microscopic examination4 ,the three states of larva1 pupa1 and imago must be considered separately4 ,the imago or perfect form is well known4 ,the males are easily distinguished from the females by the difference in structure of the antenn1 which in the males 7,pl4 ,x4 fig4 #aj1 head7 are very beautifully plumose or feathery1 whilst in the females 7fig4 #aa7 the hairs are very short--the long proboscis1 or rostrum1 or bundle of biting-organs forming the striking feature2 this difference is immediately evident to the naked eye4 ,the antenn of the males 7fig4 #aj a7 consist of numerous small joints1 from each of which arises a ring of long hairs1 giving the appearance of a tuft on each side when flattened for view as a transparent object under the microscope2 at the end are two longer joints1 the first having a small ring of shorter hairs4 ,the proboscis of the female is a very complicated organ1 consisting of six separate bristle-like pieces or set1 all nearly of the same length4 ,two of these are somewhat curved near the end1 and provided on the inside with fine teeth2 another pair consists of very thin lancet-pointed instruments2 then comes another lancet-pointed seta1 very sharp at the end1 and traversed by a canal2 next1 a stouter and darker-looking tube1 slit up underneath1 which serves to contain the two toothed set2 and lastly1 a stout and broader sheath1 also slit up throughout its length beneath1 in which all are packed4 ,this sheath has two lobes at the end1 and has some resemblance to the proboscis of the fly1 of which organ it is the representative4 ,the gnat lays its eggs in water4 ,the eggs are longish oval1 with a kind of neck at the upper end2 they are glued together side by side in large numbers1 and form a boat-like mass1 floating on the surface of the water4 ,the larv 7,pl4 ,x4 fig4 #i7 are very commonly found skipping through the water1 or hanging1 as it were1 by the tail from the surface4 ,the head is very broad2 and arising from each joint of the body are tufts of hairs4 ,near the end of the body is a tube which communicates with the trache2 and when the animal is quiet1 this tube is brought to the surface2 so that when the animal appears hanging to the surface1 it is breathing4 ,in addition to this method of respiration1 there are other respiratory organs attached to the last joint of the body1 consisting of leaf-like plates2 hence these larv have an aquatic as well as an arial respiration3 the respiratory or branchial plates also serve as a tail to aid in swimming4 ,running down the back of the larva will be seen a thin delicate vessel1 dilated opposite the thorax1 and beating or contracting at regular intervals4 ,this is the dorsal vessel1 the dilatation representing the heart of the higher animals2 and it serves to propel the colourless blood throughout the body4 ,after several moultings or castings of the skin1 to allow of the growth of the insect 7for insects grow only in the larval state71 the larva becomes transformed into the pupa 7,pl4 ,x4 fig4 #h74 ,in this state the animals still move about in the water1 and are often found suspended from its surface by two respiratory tubes1 which1 however1 are not connected with the tail1 but arise from the thorax2 and the various parts of the perfect insect may be seen through the case or skin1 within which they are closely packed4 ,when the pupa has attained its full development1 the perfect insect emerges from it1 leaving the water to fly about and seek food4 ,,tipu,,lid4--,in the water of ponds and pools a young larva 7,pl4 ,x4 fig4 #ca7 will often be met with1 which is that of ,chironomus plumsus1 a largish gnat-like insect1 belonging to the daddy-long-legs family 7,tipulid74 ,this larva exhibits the usual thirteen segments1 including the head4 ,in the young state the body is nearly colourless2 but in the mature larva it is of a blood-colour1 and about an inch in length4 ,beneath the first joint of the body are two foot-like processes covered with hair2 and at the end of the body are also two processes1 surmounted with hooks4 ,the three last joints of the body are also furnished each with a pair of fleshy processes1 those of the first pair being very short4 ,,hymenop,,tera 71 membrane1 1 wing74--,this1 which forms the sixth ,order of insects1 contains the bee1 the wasp1 the ant1 c4 ,in the ,hymenoptera there is a curious contrivance for linking the two wings on each side1 so that they may form a single piece in the flight of the insect4 ,it consists of a row of hooks1 placed upon the anterior nerve of the hind wing1 which play upon the folded-in corresponding edge of the fore wing2 the hooks1 sliding along this edge1 allow of freedom of motion1 although still holding the two wings together4 ,this structure may be well seen in the wings of the ,humble ,bee when mounted in balsam4 ,the sting of the wasp and bee is also a singular organ4 ,in both insects it is much alike1 consisting of a sheath1 slit up beneath1 in which are contained two long set1 or lancets1 with bent-back 7recurved7 teeth near the end4 ,these set are inserted into the flesh during the act of stinging1 and at the same time the poisonous secretion from two glands is forced into the wound1 which causes the severe pain resulting from the sting4 ,in the wingless neuters of the common ant1 attached to the end of the tibia 7,pl4 ,x4 fig4 #cd c7 is a beautiful pectinate process1 somewhat resembling a comb 7fig4 #cd a74 ,,lepidop,,tera 71 scale1 1 wing74--,this ,order contains the butterflies and the moths1 the entire bodies of which are covered with minute scales4 ,when the insects are handled1 these scales adhere to the fingers as a fine dust2 and on pressing a slide against the insects1 they may be removed for examination4 ,they consist of a very slender and short quill1 by which they are attached1 and a flattened plate of various forms 7,pl4 ,x4 fig4 #ai1 b1 f72 it is1 however1 generally narrower near the quill1 and expanded towards the free end1 where it is often cut into lobes or toothlike segments4 ,the scales are usually covered with continuous longitudinal lines or ridges1 with granules of colouring-matter 7pigment7 situated between the two thin layers of which the scales consist4 ,in some of them the form is that of a filament1 either simple or branched at the end 7fig4 #ai e71 when they resemble minute hairs4 ,in the males of the large white ,cabbage ,butterfly 7,pieris brassic71 certain of the scales of the wings are covered with longitudinal rows of very minute dots 7fig4 #ai f71 and have little tassel-like bodies at the end4 ,the males may be distinguished from the females by the front wings having no black spots1 while those of the females have two upon each wing4 ,when the scales are examined as they exist upon the wings of the ,lepidoptera1 they are found to be imbricated 7,pl4 ,x4 fig4 #c7 or overlapping each other like the tiles on the roof of a house4 ,the ,lepidoptera suck the honey of flowers by means of a spiral tongue 7,pl4 ,x4 fig4 #bj c7 or antlia 7antlia1 a sucking-tube72 this consists of two halves1 which represent the maxill of other insects2 and their margins are fringed with little tassel-like bodies1 probably organs of taste4 ,the antenn 7fig4 #bj a7 are many-jointed1 clubbed at the ends 7d7 in the butterflies1 and simple in the moths4 ,the palpi 7fig4 #bj b7 are short and densely covered with scales4 ,in the large eyes the facets are very distinct and suitable for examination4 ,the larv are well known as caterpillars4 ,they have six legs1 as in the perfect insects1 but rudimentary and with single claws2 also some additional pairs of pro-legs1 as they are called1 with a crown of hooks1 towards the hind part of the body4 ,the spiracles of caterpillars are very favourable for observation4 ,,neurop,,tera 71 nerve1 1 wing74--,this ,order contains the ,dragon-flies 7,libelllid71 the ,day-fly 7,ephemera71 c41 in which the wings are usually so large and so beautifully netted4 ,the species figured 7,pl4 ,x4 fig4 #a71 which is wingless1 is very common in old books and in collections of dried plants4 ,it is whitish1 mite-like1 with setaceous many-jointed antenn1 #c-;jointed tarsi1 and very broad thighs 7femora74 ,its name is ,atropos pulsatorius4 ,,hemip,,tera 71 half1 1 wing74--,this ,order contains the bugs and other noxious insects4 ,those which we shall notice are the species of ,aphis1 commonly known as ,plant-lice and ,green-fly1 which are found too frequently upon unhealthy plants4 ,the species figured 7,pl4 ,x4 fig4 #b7 is that of the geranium 7,pelargonium74 ,the head is small and notched or emarginate4 ,the body is oval and furnished behind with two prolonged tubercles1 these being covered with scales1 giving them a somewhat striated appearance 7fig4 #b b74 ,the antenn are #f-;jointed 7c71 the second joint being very small1 the last joint long1 excavated on one side1 and ringed3 these organs are reflexed over the body in the natural state4 ,there are two compound eyes1 and three simple eyes or ocelli1 forming a triangle on the top of the head4 ,the proboscis or rostrum is bent under the body1 #d-;jointed1 and contains three set1 two of them forming very slender lancets4 ,the legs are long2 the tarsi 7fig4 #b a7 #b-;jointed1 the first or basal joint being very minute1 and the last furnished with two claws4 ,in a colony of these insects1 some are winged and some wingless2 those without wings being usually in the larva state1 the pup having rudimentary wings1 and the males and females usually perfect wings4 ,aphis brassic is the destructive turnip-fly4 ,,coleop,,tera 71 sheath74--,this1 which is the last ,order to be noticed1 contains the ,beetles1 so easily recognized by their hard and horny fore wings or wing-cases4 ,the parts of the mouth in these insects are exceedingly well adapted for examination2 and as they are not fused or consolidated with each other1 they serve to illustrate the typical constitution of the organs as existing in these animals4 ,pterostichus 7,steropus7 madidus 7,pl4 ,x4 fig4 #bc7 is common in cellars and gardens among vegetable rubbish4 ,the body of this beetle is shining black1 the head projecting2 the antenn 7fig4 #bc a7 are filiform1 and compressed towards the end4 ,the thorax is somewhat rounded1 with a deep rough pit and a longitudinal stria at each posterior angle4 ,the wing-cases1 or elytra1 are longitudinally striated2 the wings1 which in most beetles are concealed beneath the elytra when the insects are at rest1 being absent4 ,the tibi of the fore legs are notched on the inside 7fig4 #bd a71 a fringe of hairs being situated in the notch2 the tarsi are #e-;jointed 7fig4 #bd b71 the first four joints being triangular1 the last elongate and terminated by two curved claws4 ,in the male the three first joints of the tarsi of the anterior legs 7fig4 #bd b7 are dilated and heart-shaped4 ,the parts of the mouth 7which are named after an analogy with those of the higher animals7 consist of the following pieces3--,an upper lip1 or lbrum 7fig4 #be a71 which is squarish 7quadrate7 and slightly notched2 a quadrate lower lip1 or lbium 7fig4 #bg71 with a process on each side1 and two #d-;jointed lip-feelers or labial palpi 7b72 and below the labium is a chin1 or mentum 7fig4 #bg a71 with a projecting bifid tooth3 these parts form the roof and the floor of the mouth4 ,next come the mandibles 7fig4 #bf71 one on each side1 which are stout1 curved1 and pointed2 beneath which are the maxill 7fig4 #bh71 also one on each side1 and provided with a fixed claw 7a71 ciliated on the inside1 and furnished with two pairs of jaw-feelers1 or maxillary palpi1 the inner 7b7 being #b-;jointed1 while the outer 7c7 are #d-;jointed4 ,it will be noticed that the jaws work laterally1 or from side to side1 and not perpendicularly as in the higher animals4 ,these parts may be found in most beetles which the observer may submit to examination1 being however somewhat modified in different genera4 ,we may consider those existing in the ,lady-birds1 or species of ,coccinella1 by way of comparison4 ,the body in these insects is very convex1 and the head sunk deeply in the thorax4 ,the antenn 7fig4 #ae7 are short1 clubbed 7clvate71 and compressed4 ,the thorax is short and lnate1 or half-moon shaped4 ,the mandibles 7fig4 #ac7 are curved1 bifid at the apex1 and with a tooth on the inside near the base4 ,the labrum 7fig4 #ad7 is transverse1 or broader than long4 ,the labium 7fig4 #ab7 is furnished with two palpi1 which are #c-;jointed4 ,the maxill 7fig4 #af7 are two-lobed1 the lobes 7b1 c7 being ciliated1 and the #d-;jointed palpi 7a7 have the last joint large and hatchet-shaped4 ,coleopterous insects undergo complete metamorphosis1 the larv being commonly known as grubs4 ,the larv of the aquatic beetles will often be met with in the water of ponds or ditches1 especially that of the common large water-beetle 7,dytiscus marginlis71 or water-boatman as it is called 7,pl4 ,x4 fig4 #g71 and in various stages of growth4 ,the structure of the mouth-organs 7fig4 #f71 which are1 however1 imperfect or rudimentary in some parts1 can be readily made out2 and their names may easily be found by comparison with what has been stated in regard to the organs of the perfect beetle4 ,examination1 c4--,the means of catching insects will readily occur to the reader4 ,a bag-net made of a curved piece of cane1 to which is fitted a bag made of net1 will serve to catch those which trust to flight for escape from their enemies1 such as the ,lepidoptera2 and these may be killed by firm pressure of the thorax between the finger and the thumb4 ,the running insects1 as the beetles1 may be caught in a spoon or with forceps2 and they may be killed by immersion in boiling water or in camphorated spirit4 ,in an excursion1 most insects may be carried in a well-corked bottle containing a little wool and a lump of camphor1 which stupifies them4 ,when the insects are dead1 the limbs should be extended into the natural position by means of pins1 the insect being transfixed by a pin run through the thorax or one of the elytra and extending into a sheet of cork4 ,to preserve them1 they may be kept in a box1 the bottom of which is covered with sheet cork1 into which the pins are stuck4 ,the smaller beetles1 c41 which cannot be transfixed with a pin1 may be mounted as opake objects upon slips of card1 the legs c41 being carefully spread out1 and gummed in position with a strong solution of gum-tragacanth in boiling water4 ,many of the smaller ,curculionid or diamond-beetles1 in which the labium forms a rostrum or beak1 with elbowed or half-bent antenn1 form beautiful opake objects when thus mounted1 on account of the brilliant scales with which they are covered4 ,there are two ways of examining insects--either in the entire state as opake objects or the separate parts mounted as transparent objects4 ,in the former case the pin with which the insect is transfixed should be stuck into a slide made of cork1 and this laid upon the stage1 or the pin may be held by the forceps4 ,in this way1 with the use of the side condenser and a low power1 the general form and arrangement of the parts of the insect can be made out4 ,the more minute details must be searched for in the individual organs which have been picked off with forceps1 and mounted in balsam4 ,if it be required to submit the parts of a dried insect to examination1 this must be previously soaked in warm water for a time1 as the legs1 c41 become very brittle when dry1 and are thus easily injured4 ,,rotator,,ia 7rta1 a wheel7 or ,,rotif,,era 7rota and fero1 to bear74--,the animals contained in this class are minute1 being just distinguishable to the naked eye as white specks4 ,they are common in long-kept infusions and among ,conferv in the water of pools and ditches4 ,their body is usually longer than broad1 often presenting indications of rings2 and at or near the posterior end is frequently found a prolongation resembling a tail1 but terminated by two short moveable thumb-like processes1 rarely a sucker1 which enable the animals to cling to objects4 ,the most characteristic organ1 however1 is a kind of rounded or oval disk1 placed at the anterior end of the body1 and furnished with cilia4 ,when these are in active motion1 the organ appears as a revolving wheel1 whence the name of ,wheel-animalcules1 by which they are sometimes designated4 ,the wheel-organ enables the animals to swim through the water1 and also brings their food to the mouth by the currents which it produces4 ,it is usually cleft into two or more lobes1 and can be retracted1 as is commonly the case when the animals are disturbed4 ,in many of these animals the body is more or less covered by a horny shell or carapace2 and in some it is fixed at the bottom of a tube1 within which it can be withdrawn4 ,on the anterior part of the body are frequently seen two or more red spots1 which represent eyes4 ,the alimentary canal is mostly distinct1 being indicated by the colour of its contents1 and it is lined with cilia4 ,towards its front portion is a gizzard 7,pl4 ,,xi4 fig4 #b a7 containing teeth1 which are sometimes attached to a jointed jaw-like framework2 these are usually in active motion4 ,no heart or blood-vessels have been observed in the ,rotatoria2 but on each side of the body in many of them is a long wavy tube1 containing at intervals minute ciliated bodies1 the cilia propelling the water through the tubes1 and so exerting an arating or respiratory function4 ,the reproduction of the ,rotatoria takes place by the formation of ova1 which may often be distinguished within the body of the parent4 ,rotifer vulgris 7,pl4 ,,xi4 fig4 #b7 is a common species4 ,it has a spindle-shaped body1 which is capable of contraction almost into a ball4 ,the front or head end is sometimes protruded 7fig4 #b71 at others retracted and obscured by the exserted disk 7fig4 #b9972 and beneath it is a tentacle-like organ1 supposed to represent an antenna 7fig4 #b b74 ,the position of the jaws is indicated at a4 ,the alimentary canal is seen running down the body2 and two ova exist1 one on each side of it1 these being often recognizable by the existence of the eyes and jaws4 ,at the end of the body are two lateral processes1 and a tail-like piece1 which can be withdrawn or protruded and is furnished with two moveable portions or toes4 ,,plate ,,xi4 ,,page #aej4 ,,rotatoria1 ,,infusoria1 c4 ,fig4 #a4 ,anguillula 7,dorylaimus71 species of4 #b4 ,rotifer vulgaris3 a1 jaws and teeth2 b1 antenna2 #b991 wheel-organ expanded4 #c4 ,pterodina patina4 #d4 ,floscularia ornata4 #e4 ,hydra viridis4 #f4 ,arcella vulgaris4 #g4 ,arcella aculeata4 #h4 ,arcella aculeata1 shell with animal4 #i4 ,arcella dentata4 #aj4 ,amba diffluens4 #ab4 ,actinophrys sol4 #ac4 ,sponge1 fibres of2 #ac a1 b1 c1 spicules of ,sponge4 #ad4 ,sertularia pumila1 polypidom4 #ae4 ,sertularia pumila1 polypidom with polypes4 #af4 ,monas lens4 #ag4 ,cercomonas globulus4 #ah4 ,cercomonas crassicauda4 #ai4 ,heteromita ovata4 #bj4 ,anthophysa ,mlleri4 #ba4 ,dinobryon sertularia4 #bb4 ,trachelomonas volvocina4 #bc4 ,chtoglena volvocina4 #bd4 ,euglena viridis4 #be4 ,astasia hmatodes4 #bf4 ,enchelys nodulosa2 a1 undergoing transverse division4 #bg4 ,oxytricha gibba2 #bg a1 side view4 #bh4 ,paramecium aurelia3 a1 contractile vesicle2 b1 a gastric sacculus4 #bi4 ,amphileptus fasciola4 #cj4 ,colpoda cucullus3 a1 contractile vesicle4 #ca4 ,nassula elegans3 a1 vesicle2 #ca b1 encysted form4 #cb4 ,coleps hirtus4 #cc4 ,vaginicola crystallina4 #cd4 ,vorticella convallaria3 a1 stalk spirally contracted2 b1 body undergoing longitudinal division4 #ce4 ,vorticella convallaria encysted and discharging the young brood4 #cf4 ,vorticella convallaria1 body with nucleus 7a74 #cg4 ,chilodon cucullulus4 #ch4 ,stentor polymorphus3 a1 body extended2 b1 body contracted2 c1 bodies aggregated around a globule of jelly2 d1 bodies adherent to the side of a glass4 #ci4 ,alyscum saltans4 #dj4 ,podophrya fixa1 or the ,podophrya-form of ,vorticella4 ,illustration3 ,plate ,,xi4 ,w ,bagg sculp ,london3 ,john ,van ,voorst4 ,pterodna patina 7,pl4 ,,xi4 fig4 #c74--,this species has a shell or carapace on the back1 a two-lobed rotatory organ1 two eyes1 and a slender wrinkled tail ciliated at the extremity4 ,the curved alimentary canal1 and the two strong muscles inclined at an angle1 are easily distinguishable4 ,flosculria ornta 7,pl4 ,,xi4 fig4 #d7 is a very beautiful member of the ,rotatoria1 and is found adhering to ,conferv and other water-plants4 ,the body is club-shaped1 and contained in a transparent tube1 the ringed narrower portion being fixed to its base4 ,the rotatory organ is divided into five or six lobes1 furnished with long1 slender1 radiating tentacular filaments2 these are not vibratile like ordinary cilia1 but can be slowly moved4 ,in the contracted state1 the filaments form a pencil-like bundle4 ,examination1 c4--,the ,rotatoria are best examined in the living state1 the drop of water in which they are viewed being very small1 so that their movements may be impeded2 and while they are struggling to escape1 the various parts of the body will come into view4 ,their preservation has been attempted by drying on a slide2 but when dead they become so contracted and altered1 that it is difficult to make out their structure4 ,should the observer wish to record any observations on their reproduction or habits1 it will be well to preserve a specimen of the jaws and teeth1 as the species might be with certainty identified by careful examination of their minute structure4 ,,entoz,a 71 within1 1 animal74--,this class consists of the parasitic worms1 as the ,tape-worm 7,tnia71 the ,thread-worm and ,round-worm 7,ascaris71 which live within the bodies of man and animals4 ,it also includes the microscopic eel-like animalcules 7species of ,anguillula7 which are found in sour paste 7,a4 gltinis71 in vinegar 7,a4 acti71 and in blighted wheat 7,a4 tritici74 ,some of the species of allied genera are met with in damp moss and in the dbris or fragments of vegetable substances decaying in water4 ,the general appearance of the microscopic species is that of a minute colourless eel1 writhing in the water 7,pl4 ,,xi4 fig4 #a74 ,their internal organs are difficult to distinguish4 ,the alimentary canal is usually evident1 and dilated into a kind of stomach1 containing near its commencement some rod-like or otherwise-formed teeth4 ,in the species figured there are two apparently tubular lancets1 which are capable of protrusion1 and evidently serve to wound the prey4 ,,chapter ,,xii4 ,,radiata4 ,descending in the scale of animal organization1 we come next to the subkingdom ,,radi,,ta1 or that in which the parts are arranged in a radiate manner around a centre4 ,of this there are three classes1--the ,,echinoder,,mata 71 hedgehog1 1 skin71 containing the ,sea-urchins 7,echnus71 ,starfishes1 c41 in which the skin is furnished with hard calcareous projecting spines or curiously formed imbedded calcareous corpuscles1 forming a rudimentary skeleton2 the ,,acal,,ph 71 a nettle71 or ,sea-nettles2 and the ,,pol,,ypi 71 many1 1 foot71 to which we shall confine our notice4 ,it may be remarked that the last two classes have recently been united to form the single class ,c,,lenter,,ta 71 hollow1 1 intestine74 ,,polypi4--,these animals are mostly marine4 ,they are either single 7,pl4 ,,xi4 fig4 #e71 or compound 7,pl4 ,,xi4 fig4 #ae71 i4 e4 the bodies are united2 in the latter case the bodies being usually situated in horny cells upon a branched polypidom4 ,but in many of them1 which do not occur in this country1 there is an internal solid calcareous skeleton1 of which coral is an example4 ,the animal bodies are soft1 and furnished at the front end with a crown of tentacles 7fig4 #ae a72 these are contractile1 and serve to enable the animals to catch their prey4 ,the horny1 branched1 and plant-like polypidoms are often found on the seashore1 and are popularly confounded with sea-weeds4 ,hydra vulgris 7,pl4 ,,xi4 fig4 #e7 is a fresh-water species1 which is commonly met with among collections of water-plants1 and may generally be obtained by collecting some of these and placing them in a glass jar of fresh water4 ,when the water has stood for some hours1 the ,polypes will be seen1 on careful examination1 adhering to the sides of the glass4 ,the body of the animals is cylindrical1 hollow1 and furnished with from six to ten tentacles1 arranged in a circle1 in the centre of which is the mouth4 ,the tentacles are hollow1 and communicate with the cavity of the body4 ,on examination with a high power1 the tentacles will be found to exhibit minute oval sacs1 containing a long fibre coiled up within them2 and when the tentacles are touched by any foreign body1 the fibres are suddenly discharged4 ,these are the stinging or urticating organs4 ,the ,hydr move very slowly2 but the body is very contractile1 and is often seen of various forms4 ,when a minute animal1 as an ,entomostracan1 happens to come into contact with the tentacles1 these curve around it1 holding it firmly1 and finally bringing it to the mouth4 ,it is then forced into the cavity of the body of the animal1 where it is digested1 the remains being discharged at the mouth4 ,the movements of the ,hydra1 when devouring its prey1 form a very curious and interesting spectacle4 ,the ,hydr are propagated by budding or gemmation1 also by the formation of capsules in the walls of the body1 containing ova and spermatozoa4 ,the young ,polypes formed by budding are represented in the figure1 adhering to the base of the parent4 ,sertulria pmila 7,pl4 ,,xi4 fig4 #ae7 is a marine species1 the polypidom being frequently found adhering to ,fuci and other sea-weeds2 it is about half an inch long4 ,the cells are opposite1 pointed at the ends1 and with an oblique orifice4 ,the tentacles are fourteen in this species4 ,in the summer large ovate cells are found1 arising from the polypidom2 these contain the eggs1 and are called ovisacs or ovigerous vesicles4 ,,chapter ,,xiii4 ,,protoz,a 71 ,,first1 1 ,,animal74 ,the members of this subkingdom are the lowest in the scale of animal organization1 their bodies consisting of a soft gelatinous and structureless mass1 which has a remarkable tendency to form little cavities or vacuoles in its substance1 and is called sarcode 71 flesh74 ,they exhibit no organs1 unless the cilia and certain variable processes formed of the common substance of the body1 and which form their agents of locomotion1 be considered as such1--this substance exercising the combined functions of motion1 sensation1 and secretion1 for which separate organs exist in the higher animals4 ,,rhizop,,oda 71 root1 1 foot74--,the animals belonging to this class consist of the structureless colourless substance to which reference has been made as sarcode1 and they exhibit no organs4 ,the sarcodic body is slowly contractile1 and portions of it can be protruded at will in the form of irregular root-like processes1 acting both as legs for locomotion and as tentacles by which the animal grasps its prey1 which is then forced into the substance of the body1 where it becomes surrounded by the surface1 and a cavity is formed1 within which it is digested4 ,amba diffluens 7,pl4 ,,xi4 fig4 #aj7 is common in water in which portions of plants have been kept for some time4 ,when first placed on the slide1 the body appears as a minute1 transparent1 rounded mass of jelly2 but if observed for some time1 it will be seen slowly to protrude its root-like processes2 and foreign bodies1 as ,diatomace or other minute ,alg1 will often be found imbedded in its substance4 ,arcella vulgris 7,pl4 ,,xi4 fig4 #f7 is found among ,conferv in ponds and ditch-water4 ,it is contained in a hemispherical shell or carapace1 from the round orifice of which the lobed processes are protruded4 ,the shell is covered with minute pits4 ,arcella aculeta 7,pl4 ,,xi4 fig4 #g7 has the convex shell furnished with spines2 fig4 #h represents the animal with its processes extended2 while ,arcella dentta 7,pl4 ,,xi4 fig4 #i7 exhibits an angular or somewhat toothed membranous shell4 ,both the latter species are met with in the same localities as the first4 ,actnophrys sol 7,pl4 ,,xi4 fig4 #ab7 is a very beautiful and excessively delicate ,rhizopod4 ,the body is spherical1 and covered with very delicate and slender cilia-like processes4 ,its movements are exceedingly slow1 and can only be observed by prolonged watching4 ,the body appears to be reticulated1 from the presence of numerous vacuoles4 ,two large groups of genera and species of ,rhizopoda1 the animal bodies possessing the above general characters1 mostly with very slender processes1 exist1 in one of which 7the ,,foraminifera7 they are contained in calcareous shells1 often of elegant forms2 while in the other 7the ,,polycystina7 the shells are siliceous or composed of flint1 both kinds of shells being perforated with holes4 ,these shells1 which occur in the fossil state in enormous numbers1 sometimes forming mountain-masses1 are extremely beautiful objects for the microscope4 ,,spon,,gi4--,this class contains the ,sponges1 almost all of which are marine and foreign1 and therefore not likely to come under observation in the perfect state4 ,the substance commonly called sponge is the horny skeleton of the animal1 consisting usually of rounded fibres 7,pl4 ,,xi4 fig4 #ac71 irregularly netted and interlacing4 ,the surface of a sponge exhibits minute pores and larger pouting orifices2 the former of which admit currents of water1 to be discharged at the latter1 both being the mouths of continuous channels4 ,the surfaces of the channels are lined with sarcodic matter1 which takes the form of ciliated ambiform bodies1 by which the currents of liquid are produced4 ,the horny fibres of sponges are strengthened by little siliceous or flinty bodies of various forms 7,pl4 ,,xi4 fig4 #ac a1 b1 c71 which are imbedded in the substance of the fibres or attached to their surface1 and form very curious microscopic objects4 ,they are called spicula 7spiculum1 a dart71 being often of a pointed form4 ,in some sponges they are calcareous4 ,,infusor,,ia4--,the animals contained in this class are usually very minute1 being rarely even perceptible to the naked eye1 except when existing in very large numbers1 so as to render the water milky1 green1 or red4 ,they are found in all kinds of water1 but especially in stagnant pools and in decomposing solutions or infusions of vegetable matters4 ,the true structure of their bodies is a matter of doubt1 some authors having considered them as being highly organized1 while others have regarded them as consisting of simple cells2 and whether they are correctly referred to the ,protozoa must remain at present a matter of doubt4 ,the body is of various forms1 as represented in ,plate ,,xi4 figs4 #af-dj4 ,in some of them it consists of a simple sarcodic mass1 evidently without any outer skin1 as shown by its ready adhesion and laceration on accidental contact with foreign bodies2 while in others the surface is regularly dotted with little depressions1 or with nodules1 so as to resemble a definitely organized structure4 ,the most striking character of the ,infusoria is the presence of vibratile cilia1 which are variously arranged2 in some entirely covering the body1 irregularly or in regular rows1 in others being situated at definite parts only4 ,by the action of the cilia they are enabled to swim freely in the water1 also to obtain their food1 which consists of minute ,alg or fragments of animal matter4 ,in many of them there is a special row or set of cilia1 which1 by the currents it produces1 urges the particles of food suspended in the water towards the mouth4 ,the cilia also act as respiratory organs1 by changing the water with which their bodies are in contact4 ,in some of the species there are stout bristles or set1 by which they are enabled to crawl upon water-plants4 ,on carefully examining the bodies of the ,infusoria1 rounded granular spots will be seen1 frequently containing minute ,alg1 c4 7fig4 #bh b74 ,these spots are the digestive cavities1 and have been called gastric sacculi2 but whether they are definite sacs or mere excavations1 formed by the particles of food having been forced into the softer internal substance of the body1 has not been positively determined4 ,the sacculi may be filled artificially by mixing very fine indigo1 or carmine1 on a slide with the water in which the ,infusoria are contained4 ,a definite food-tube or alimentary canal has been detected in a few of the ,infusoria2 but it cannot be shown to exist in the majority of them4 ,a mouth exists in most of them1 and is sometimes indicated by a row or set of cilia somewhat larger than those existing upon other parts of the body1 and leading to or placed near it4 ,the particles of food which have entered the body are often seen to pass round it1 as if circulating1 descending on one side and ascending on the other4 ,in addition to the gastric sacculi1 certain clear transparent spots may also be seen within the body1 appearing light or dark according to the adjustment of the focus4 ,if these are attentively watched1 they will be seen to contract and finally disappear1 becoming again distended and vanishing at tolerably regular intervals4 ,these are the contractile vesicles 7figs4 #bg a1 #bh a1 #cg a71 and they contain a clear liquid1 the nature of which is uncertain4 ,in many of the ,infusoria is a round or elongate granular body 7figs4 #ca a1 #cf a71 which is called the nucleus1 the term having been applied to it from a notion that the ,infusoria consisted of simple cells4 ,a minute red spot is also often seen at the anterior end of the body1 which is supposed to represent an eye1 and is called an eye-spot4 ,the ,infusoria are propagated in several ways3--by budding or gemmation1 new beings sprouting out in a bud-like form1 usually from the base of the parent2 by division1 either transverse 7fig4 #bf a7 or longitudinal 7fig4 #cd b71 of the body gradually into two parts1 each of which subsequently becomes a perfect animal2 by encysting1 the body contracting into a globular form1 and forming a firm coat around it1 the contents becoming resolved into a numerous progeny of young2 and by conjugation and the agency of spermatozoa and ova4 ,we will now proceed to the examination of a few species1 arranging them in the order of the families to which they belong4 ,,monad,,ina4--,in this family the bodies of the ,infusoria are very soft1 and without a skin or integument2 they are also exceedingly minute1 and will not admit the particles of indigo4 ,monas lens 7,pl4 ,,xi4 fig4 #af7 is very minute1 and commonly found in old infusions4 ,its body is rounded and flattened1 and granular on the surface4 ,at the front end of the body is a whip-like or flagelliform 7flagellum1 a whip7 filament1 differing from a cilium in being rigid at the base and moveable at the end only1 by which it is enabled to row itself through the water with a wriggling motion4 ,cercomonas globulus 7fig4 #ag7 has a spherical body1 with two flagelliform filaments1 one arising from the front1 the other from the end of the body4 ,in ,cercomonas crassicauda 7fig4 #ah7 the posterior filament is replaced by a tail-like narrowing of the body4 ,heteromita ovta 7fig4 #ai7 has the body ovate1 with two long anterior flagelliform filaments1 one of which is directed forwards1 while the other trails behind4 ,anthophysa mlleri 7fig4 #bj7 has the monad bodies arranged in little heads at the ends of an irregularly branched brown stalk4 ,after a time they become detached and revolve freely in the water4 ,,dinobry,,ina4--,dinobryon sertulria 7,pl4 ,,xi4 fig4 #ba7 forms a minute ,sertularia-like polypidom1 consisting of rows of cells1 each containing an oval monad with a single anterior filament4 ,the two last species are common in bog-water4 ,,thecamonad,,ina4--,in these ,infusoria the body is inclosed in a firm and sometimes brittle shell or carapace4 ,trachelomonas volvocina 7,pl4 ,,xi4 fig4 #bb7 has a spherical red shell1 the body being furnished with a single filament and a minute red eye-spot2 while ,chtoglna volvocina 7fig4 #bc7 has an oblong shell1 covered with little spines4 ,,eugl,,nia4--,in this family the form of the body is constantly changing1 being at one time spherical1 at another fusiform or ovate4 ,it is covered with a contractile skin or firmer external portion1 and has one or more flagelliform filaments for locomotion4 ,the species are common in stagnant pools1 often colouring the water green or red4 ,euglna viridis 7,pl4 ,,xi4 fig4 #bd7 has a spindle-shaped body when fully expanded1 the ends being pale2 and at the front end is a red eye-spot4 ,astsia hmatdes 7fig4 #be71 which is probably a form of the ,euglena1 is found in stagnant pools1 which it renders red4 ,it has no eye-spot4 ,,ench,,lia4--,these ,infusoria are found in stagnant water and in decomposing infusions4 ,the body is covered with cilia variously arranged1 but there is no integument nor mouth4 ,enchelys nodulsa 7,pl4 ,,xi4 fig4 #bf7 has a colourless1 oblong1 irregularly nodular body1 coated with very slender radiating cilia1 and often exhibits numerous vacuoles4 ,it is frequently found undergoing transverse division 7fig4 #bf a71 the body becoming gradually constricted until it separates into two parts1 which become perfect animals4 ,alyscum saltans 7fig4 #ci7 has an ovoid-oblong1 slightly furrowed body1 surrounded with radiating cilia1 and has a side bundle of long retractile cilia1 by means of which it leaps from place to place in the water4 ,,ker,,nia4--,in this family the body is soft1 irregularly ciliated1 without a special integument1 but has an oblique row of vibratile cilia leading to the mouth1 and stouter cilia or bristles 7set7 on certain parts of the body4 ,the sacculi often contain ,diatomace1 c4 ,oxytricha gibba 7,pl4 ,,xi4 fig4 #bg7 has a colourless1 oblong body1 somewhat expanded in the middle1 with set at the two ends4 ,in the side view 7fig4 #bg a71 the body is seen to be convex above and flattened beneath4 ,,paramec,,ina4--,the species belonging to this family have a soft1 flexible body1 which is usually oblong and flattened beneath1 with an integument covered regularly with pits and rows of cilia4 ,colpoda cucullus 7,pl4 ,,xi4 fig4 #cj7 has a slightly compressed body1 ciliated all over1 and kidney-shaped or rounded on one side and notched on the other1 the surface exhibiting rows of nodules4 ,the mouth is situated at the bottom of the notch4 ,paramcium aurlia 7fig4 #bh7 has the body oblong or oblong-ovate1 the mouth being placed near the anterior third of its under part4 ,this infusorium is of comparatively large size1 and is often found in immense numbers in infusions1 which it renders milky4 ,it is admirably adapted for showing the sacculi1 which are easily filled with indigo4 ,the body exhibits two remarkable stellate organs1 consisting of a central contractile vesicle1 surrounded by several radiately placed oval vesicles1 which may be seen to contract and dilate with great regularity4 ,the body is coated with very fine cilia4 ,amphileptus fascola 7fig4 #bi7 is furnished with an elongate fusiform or lanceolate flattened body1 with a lateral oblique mouth4 ,chilodon cucullulus 7fig4 #cg7 has an oblong thin body1 irregularly wavy on the sides2 the mouth being situated obliquely in front of the middle1 and furnished with a cylinder of parallel rod-like teeth4 ,nassula elegans 7fig4 #ca7 has the body ovoid or oblong1 becoming globular when contracted1 the mouth being furnished with teeth as in ,chilodon4 ,it is often found among ,oscillatori4 ,,urceolar,,na4--,vorticella convallria 7,pl4 ,,xi4 fig4 #cd7 is very commonly met with in decomposing infusions4 ,the bell-shaped body is fixed at the end of a slender stalk1 which is often seen to be extended and then suddenly contracted into a spiral 7fig4 #cd a74 ,the cilia are arranged around a raised rim at the front of the body1 and extend down a fissure leading to the mouth4 ,the sacculi of this infusorium may be readily filled with indigo4 ,the process of longitudinal division may also often be observed1 taking about an hour for its completion2 and when the new individual is about to separate from the parent1 a ring of cilia may be noticed to have sprung up around the base 7fig4 #cf74 ,the encysting process is also often visible1 the cilia disappearing1 and the body becoming globular and secreting a cyst around it2 after a time the contents become resolved into a number of embryos1 which escape by the bursting of the cyst 7fig4 #ce74 ,in some cases the ,vorticella assumes the form of a ,podophrya 7fig4 #dj71 the surface becoming covered with tentacle-like processes4 ,this ,podophrya was formerly considered a distinct species4 ,vaginicola crystallina 7fig4 #cc7 is contained in a crystalline tube1 from which the body can be protruded4 ,the body is of variable form1 presenting when fully extended a trumpet shape4 ,the cilia exist at the anterior end1 and extend down a lateral fissure as in ,vorticella4 ,it is found attached to ,conferv in the water of ponds and bog-pools4 ,stentor polymorphus 7fig4 #ch7 is a very beautiful trumpet-shaped infusorium1 the body being covered with spiral rows of cilia4 ,the rim is furnished with stouter cilia1 its margins at the notch being spirally turned inwards4 ,this infusorium is often found in little groups attached to a gelatinous mass 7fig4 #ch c72 and it is met with also in a free or unattached state4 ,,colep,,ina4--,cleps hirtus 7fig4 #cb7 has a barrel-shaped carapace1 transversely and longitudinally furrowed1 the furrows being occupied by cilia4 ,it has two or three spines behind1 and ten or twelve at the front end of the carapace4 ,it is common among ,conferv1 and is very voracious1 feeding upon dead ,entomostraca1 c42 and if disturbed1 at its meal by moving the cover1 it will soon return and resume feeding as before4 ,examination4--,the ,infusoria must be examined during life2 for they are so altered by preservative liquids that they cannot be well preserved4 ,the shells of those that are provided with them may be kept simply dried upon a slide1 and in this way a few will retain their form1 and the cilia of all may be more easily distinguished2 the vacuoles may also then be seen very distinctly4 ,when they are confined in a small quantity of water and are about to die1 a curious phenomenon may be observed in them1 a number of oil-like sarcodic globules exuding from the body1 and within these1 vacuoles may often be seen to form spontaneously4 ,the ,infusoria may be collected in small phials2 but it is difficult to keep them1 as they form the food of the ,entomostraca1 the ,rotatoria1 and the larv of insects2 so that their enemies are very numerous1 and they soon disappear4 99 99 99 99 99 ,,classification4--,before leaving the subject of living bodies1 it may be well to make a few remarks upon their systematic relation as defined by classification4 ,all natural bodies are referable to one of three great kingdoms1 viz4 the ,animal1 the ,vegetable1 or the ,mineral ,kingdom4 ,the bodies belonging to the latter seldom come under the notice of the microscopic observer1 as they are mostly visible to the naked eye1 and their minute structure is the same as that of the larger masses4 ,the general structure of the members of the vegetable and animal kingdoms has been illustrated in the preceding pages4 ,these bodies are distinguished from those of the mineral kingdom by their vital power of appropriating surrounding matters to their own nutrition and growth--this power being exercised by their organs1 or1 in the lowest forms1 by any portion of their substance4 ,hence animals and vegetables or plants are termed organic bodies1 while minerals are termed inorganic bodies1 as having no organs2 and the material of which organic bodies consist is termed organic matter1 that of minerals being inorganic matter4 ,but in both animals and plants inorganic matter is mixed with the organic matter1 having been taken up or absorbed from the inorganic kingdom1 although it does not usually exist in its characteristic condition1 which is that of crystals1 i4 e4 angular solids1 as crystals of ,epsom salts1 c4 ,the individual members of the animal and vegetable kingdoms are systematically divided into certain groups1 and these into successively smaller groups until we arrive at the species4 ,these groups are founded upon the possession of certain points of resemblance by their members1 forming the distinguishing characters1 and their names are significant and definite4 ,they usually run as follows1 the larger and higher groups standing first in order3--,kingdoms1 ,subkingdoms1 ,classes1 ,orders1 ,families1 ,tribes1 ,genera1 and ,species4 ,but it must be observed that the term species has a different value from that of the other terms2 for the individuals of which the species consist are not only related by resemblance of structure1 but also by their origin--being supposed to have derived their origin from a parent of original creation2 while the other groups have1 as far as we know1 no other relation than that of similarity of structure4 ,it is obvious that the characters of the various groups might be founded upon peculiarities of any kind4 ,but on this point two methods must be specially distinguished1 in one of which the groups are founded upon the sum of all the peculiarities1 while in the other they are based upon the structure of single parts or organs4 ,in the former case the system is called natural1 in the latter artificial4 ,and while the latter often brings together beings which have perhaps but one or two points of resemblance1 and separates others which are closely related1 the former associates those which are really and naturally similar4 ,all the groups have special names1 so that they may be referred to and spoken of as in the case of common things2 the names being composed of ,greek or ,latin words1 so that they may be intelligible to all nations2 and as these are dead languages1 they will remain good for all time4 ,in mentioning the name of an animal or plant1 the name of the genus is always used with that of the species2 thus1 the name of ,chickweed is ,stellaria media4 ,because there are mostly several species in a genus2 so that if the name of the genus only were used1 the species meant would be uncertain2 and as there are often species of the same name in different genera1 if the name of the species only were used1 the genus meant would be doubtful4 ,the classification of animals and plants serves two important purposes3 one is that the structural peculiarities and affinities of the groups may be contrasted and a knowledge of their absolute and their differential characters acquired1 and for this a natural system is eminently serviceable2 the second is that of enabling any animal or plant to be simply distinguished from any other1 for which an artificial or analytical system is extremely useful4 ,,chapter ,,xiv4 ,,optical ,,principles4 ,we shall now devote a few pages to the consideration of the nature of light1 and the optical principles involved in the construction and use of the microscope4 ,two theories of light have been propounded4 ,according to one1 light consists of minute particles emanating from self-luminous bodies1 as the sun1 a candle1 or a red-hot piece of iron2 this is called the corpuscular theory4 ,according to the other1 light consists of waves or undulations like those of water or the ears of corn set in motion by the wind1 of the molecules of an extremely subtle and rarified elastic matter1 called ether1 existing everywhere1 and set in motion by the causes which produce light2 this is called the undulatory theory4 ,the consideration of the merits of these two theories would be foreign to our purpose3 suffice it to say that the evidence in favour of the undulatory theory preponderates1 so that the corpuscular theory is now laid aside4 ,it will often be requisite to make use of the term ray of light1 by which must be understood the smallest bundle of luminous undulations which can be separated from a mass of light--as by passing light through a small hole in an opake body1 or by any equivalent method4 ,the most casual observer must have noticed that the rays of light move in straight lines2 as when the sun's rays are seen entering a dark room through a small window or other aperture1 their direction being then distinctly visible2 the manner in which ordinary shadows are formed also illustrates the same fact4 ,refraction4--,but when the rays in their passage impinge or are incident upon and enter a transparent medium or material1 of a different density from that which they were at first traversing1 their course becomes altered1 and the line of their direction broken1 whence they are said to be refracted4 ,if the medium upon which the rays impinge be denser than that through which they were at first passing1 they will be refracted towards a line perpendicular to the surface1 or they will be refracted towards the perpendicular1 as it is expressed4 ,thus1 as shown in ,pl4 ,,xii4 fig4 #a1 the incident ray i1 entering the plate of glass1 will be refracted at its surface in the direction a r1 towards the line p1 which is perpendicular to the surface4 ,the extent to which the rays undergo refraction depends upon the degree of density of the medium1 and varies in the case of each individual substance2 but it follows a definite law4 ,if1 as in ,pl4 ,,xii4 fig4 #b1 a circle be drawn around the point b1 at which the ray a is incident1 b r representing the refracted ray1 the lines s i and t r1 drawn at right angles to the perpendicular p1 will form respectively the sines1 as they are called1 of the angles s b i and t b r2 s i being the sine of the angle of incidence s b i1 or the angle formed by the incident ray with the perpendicular1 and t r the sine of the angle of refraction t b r1 or of that formed by the refracted ray with the perpendicular4 ,these sines1 for brevity1 are called the sines of incidence and of refraction2 and they bear a constant ratio or proportion to each other4 ,taking the sine of refraction as the unit1 or as #a1 the value of the sine of incidence represents the refractive index or the refractive power of the medium for a ray entering the medium from a vacuum2 or1 the refractive power of air being extremely small1 the value of the sine of incidence may be considered as representing the refractive power from air into the medium4 ,,plate ,,xii4 ,,page #afh4 ,,optical ,,principles4 ,fig4 #a4 ,refraction through a glass plate4 #b4 ,law of refraction4 #c4 ,reflexion from a plane surface4 #d4 ,reflexion from a concave mirror4 #e4 ,refraction at a curved surface4 #f4 ,a doubly convex lens4 #g4 ,a plano-convex lens4 #h4 ,a doubly concave lens4 #i4 ,a plano-concave lens4 #aj4 ,a concavo-convex lens1 or meniscus4 #aa4 ,refraction through a convex lens4 #ab4 ,relation of a convex lens to prisms4 #ac4 ,relation of a concave lens to prisms4 #ad4 ,refraction of parallel rays through a convex lens4 #ae4 ,refraction of converging rays through a convex lens4 #af4 ,refraction of diverging rays through a convex lens4 #ag4 ,refraction of parallel rays through a concave lens4 #ah4 ,spherical aberration4 #ai4 ,dispersion and formation of a spectrum4 #bj4 ,chromatic aberration4 #ba4 ,formation of images in the eye4 #bb4 ,angle of vision4 #bc4 ,objects too near the eye4 #bd4 ,action of convex lens in vision4 #be4 ,aplanatism4 #bf4 ,aberration produced by cover4 #bg4 ,course of rays through the microscope4 #bh4 ,achromatism4 #bi4 ,waves of light conspiring 7a1 b71 and interfering 7b1 c74 #cj4 ,polarization3 t1 tourmaline2 d1 crystal2 s1 crystal of calcareous spar4 ,illustration3 ,plate ,,xii4 ,w ,bagg sculp ,london3 ,john ,van ,voorst4 ,although the ratio of the sines is constant1 the refractive index varies in different media4 ,thus that of air is #ajjjc2 of water1 #accf2 of ,canada balsam1 #aedi2 of crown glass1 from which window-panes are made1 #aece2 of flint glass1 from which bottles are made1 #af2 of ,faraday's heavy glass1 composed of silicated borate of lead1 #ah2 and of that consisting of borate of lead1 #bj4 ,a knowledge of this 8law of the sines0 is of practical importance in determining the direction which the rays will pursue when transmitted through glass lenses1 c4 the refractive index of which is known2 or in ascertaining the curve which should be given to their surfaces for producing a particular refraction and focal length4 ,thus1 supposing the plate of glass in ,pl4 ,i4 fig4 #b to consist of crown glass1 the refractive index of which is #ae1 the length of the sine of refraction1 t r1 will be equal to one part or dimension1 while the sine of incidence1 s i1 is equal to one part and a half4 ,it must be remarked that when light is incident at a right angle to the surface of the medium1 no refraction takes place1 the transmitted ray pursuing its original course4 ,when a ray of light leaves a denser medium1 such as glass1 to enter a rarer medium1 such as air1 it becomes refracted from the perpendicular4 ,in such case1 the angle of refraction being greater than the angle of incidence1 its sine will also be greater than that of the latter2 but the ratio is still preserved4 ,reflexion4--,when rays of light fall upon a plane surface1 as the flat surface of the mirror1 a greater or less number of them are reflected1 and this according to a definite law1 by which the angle of incidence1 or that formed by the incident ray with the perpendicular1 is equal to the angle of reflexion1 or that formed by the reflected ray with the same4 ,thus1 as shown in ,pl4 ,,xii4 fig4 #c1 the angle i b p1 formed by the incident ray i b with the perpendicular p1 is equal to the angle p b r1 formed by the reflected ray b r with the perpendicular p b4 ,if the body upon the surface of which the rays are incident be transparent1 some of the rays will be refracted and will pass through it1 whilst others will be reflected4 ,the proportion of those reflected is smallest when the rays are incident perpendicularly to the surface2 but this increases as the incident rays become more oblique1 i4 e4 as the angle of incidence becomes greater1 although at no degree of obliquity are the whole of the rays reflected4 ,the case is different1 however1 with those rays which enter the substance and impinge upon its inner or second surface2 for these at a particular angle of incidence undergo total reflexion1 so that none of the rays are transmitted at the second surface4 ,the angle of total reflexion is constant for the same medium1 but different for different media3 thus in crown glass it is equal to about #dj1 in flint-glass #ch1 c42 and this internal reflexion from the second surface of transparent media is more perfect than that occurring at the surface of opake reflecting surfaces or mirrors4 ,if the reflecting surface be concave1 as in ,pl4 ,,xii4 fig4 #d1 parallel rays will be reflected to a focus a1 nearer the mirror than the centre of its curvature b1 and this focus is called the principal focus2 while diverging rays are brought to a focus nearer the centre of curvature2 and converging rays form a focus further from the centre of curvature4 ,lenses4--,in most instances1 as far as the microscope is concerned1 the surfaces of the glass through which the rays of light are transmitted are not plane or flat1 but curved-being either convex or concave1 and belonging to convex or concave lenses4 ,in considering the course of rays through curved surfaces1 the refraction may be viewed as taking place at a plane surface forming a tangent at the point of incidence of each ray2 or each curved surface may be regarded as consisting of a number of minute plane surfaces placed at right angles to the perpendicular4 ,thus1 in ,pl4 ,,xii4 fig4 #e1 the ray a1 incident at the point b of the curved surface1 is refracted towards the perpendicular p1 as if it had fallen upon the plane surface represented by the tangent t4 ,the forms of the most common lenses are represented in ,pl4 ,,xii4 figs4 #f-aj2--;fig4 #f being doubly convex1 or both surfaces being convex2 fig4 #g1 plano-convex1 or one surface plane1 the other convex2 fig4 #h1 doubly concave1 or both surfaces being concave2 fig4 #i1 plano-concave1 one surface being plane1 the other concave2 and fig4 #aj is a meniscus1 in which one surface is convex and the other concave4 ,the curved surfaces of lenses are usually portions of spheres4 ,the manner in which the course of a ray may be traced through a lens is illustrated by ,pl4 ,i4 fig4 #aa1 which requires no explanation after what has been already stated4 ,to facilitate the comprehension of the general action of lenses1 they may be regarded as composed of two triangular prisms1 with their bases in contact in a convex lens1 as in fig4 #ab2 their apices being opposed in a concave lens1 as in fig4 #ac4 ,the point to which the rays converge after passing through a convex lens is called the focus 7,pl4 ,,xii4 fig4 #ad f71 the distance of which from the centre of the lens1 called the focal length1 obviously depends upon the direction of the incident rays4 ,when these are parallel1 which those coming from distant objects may be considered to be1 the focus at which they meet is called the principal focus1 or the focus for parallel rays3 thus1 in ,pl4 ,,xii4 fig4 #ad1 the parallel rays meet at f1 which is the principal focus4 ,if the incident rays are convergent1 as in ,pl4 ,,xii4 fig4 #ae1 the focus o will be situated nearer the lens than the principal focus1 f4 ,if1 on the other hand1 they are divergent1 as in ,pl4 ,,xii4 fig4 #af1 the focus f will be situated further from the lens than the principal focus o4 ,by concave lenses the incident rays are rendered divergent1 as in ,pl4 ,,xii4 fig4 #ag1 as if they emanated from a point f1 situated on the same side of the lens as that upon which the rays are incident1 and called the virtual focus4 ,spherical aberration4--,although1 as a general expression1 we have stated that the rays of light meet at a focus on passing through a convex lens1 this is not strictly correct4 ,for1 in ordinary convex lenses1 the marginal rays are more refracted than the central ones1 and meet at focal points nearer the lens than the latter1 as shown in ,pl4 ,,xii4 fig4 #ah4 ,this important defect is called spherical aberration1 and arises from the lateral rays being incident upon more oblique portions of the curved surface of the lens than the central rays4 ,hence objects seen through such lenses appear misty and confused1 the central and lateral parts of a flat object not being visible at the same time2 and even when the marginal parts are visible1 they appear distorted or deformed4 ,spherical aberration is greatest in the most convex lenses2 and1 in a plano-convex lens1 it is least when parallel rays enter at or emerge from its convex surface4 ,in certain lenses1 the convex surface of which has the form of a parabola1 a hyperbola1 or an ellipse1 the spherical aberration is absent2 but it is impossible to grind microscopic lenses of these forms with absolute accuracy1 so that the fact is of no practical value4 ,the form of simple convex lens most free from aberration is that in which the curves of the two surfaces form parts of a sphere1 the radii of the curves being as #a to #f2 the focal length being rather less than twice the length of the radius of the most convex surface4 ,this form of lens comes very near to a plano-convex lens1 which is consequently the best form for a simple lens4 ,dispersion1 or ,chromatic ,aberration4--,the rays of light have so far been considered as simple4 ,they are1 however1 in reality compound1 consisting of a number of primary-coloured rays1 of which seven kinds are easily distinguishable1 viz4 red1 orange1 yellow1 green1 blue1 indigo1 and violet4 ,the coloured rays of the sun are1 as is well known1 often seen separated by the action of the triangular glass bars or prisms forming the lustres of a chandelier2 the separation arising from the different refrangibility of the coloured rays1 by which each is refracted to a different degree from that of the others4 ,this is shown in ,pl4 ,,xii4 fig4 #ai1 representing a ray of white light entering a triangular prism1 at the surface of which the paths of the rays become different according to the degree of their refrangibility1 whence they emerge separately1 forming a spectrum at v r2 the most refrangible violet rays 7v7 being most refracted1 the less refrangible red 7r7 least so1 the intermediate rays being refracted to intermediate degrees according to their respective refrangibilities4 ,this separation of the coloured rays is called dispersion2 and as different substances or media disperse the coloured rays over a larger or smaller space1 so as to produce spectra of different lengths1 they are said to possess different dispersive powers4 ,thus the dispersive power of flint glass and balsam are about equal1 while that of crown glass is considerably less4 ,the extent to which dispersion is produced by the same medium also depends upon the angle of the prism1 being greater as the angle is larger2 increased obliquity of the incident light also increases the dispersion1 so that the spectrum produced by a small prism may be equal to that produced by a larger one upon which the light is less obliquely incident4 ,in consequence of the dispersion of light1 rays passing through a convex lens do not meet at a single point or focus 7,pl4 ,,xii4 fig4 #bj71 but form as many foci as there are coloured rays4 ,when the spectrum is received upon a convex lens1 the coloured rays are brought to a focus1 and the light appears again white2 for it is only when the primary-coloured rays are parallel1 and seen close together1 that they produce the impression of white or colourless light4 ,the spectra produced by different dispersive media not only differ in length1 but also in the breadth of the coloured spaces not being in the same ratio to each other2 hence the spectra are said to be irrational1 or the dispersion is said to be irrational4 ,vision4--,the visibility of an object depends upon the rays of light which emanate from each point of its surface presented to the eye being brought to a focus upon the retina or expansion of the nerve of sight lining the inside of the back of the eye2 so that1 an image of each point being impressed upon the retina1 the sum of the images forms the compound image of the entire object4 ,the manner in which the image is formed is shown in ,pl4 ,,xii4 fig4 #ba1 in which1 to prevent confusion1 the rays coming from three points of the arrow only have been represented4 ,the rays diverging from these three points1 a b c1 form cones in contact by their bases2 the apex of each cone outside the eye being situated at the points a b c1 the common base of each being situated at the crystalline lens x1 immediately behind the pupil or rounded aperture in the coloured curtain of the eye1 called the iris1 i i1 and which limits the base of the cones4 ,the apices of the cones within the eye1 abc1 are formed by the rays brought to foci upon the retina by the crystalline lens4 ,the marginal cones of rays coming from the object cross within the eye1 so that the uppermost rays from the object become lowermost upon the retina1 and thus an inverted image of the object is formed4 ,this appears to the eye to be erect1 because the eye or rather the mind judges the parts of an object to be situated in that direction in which the rays coming from them are impressed upon it4 ,hence1 as in fig4 #ba1 the rays impressed upon the retina at the lower part a1 appear to come from the upper part of the cross1 although they are lowermost in the image1 and so on for the other rays4 ,for distinct vision the rays of each cone must be parallel1 or nearly so4 ,angle of ,vision4--,the marginal rays coming from the object cross at a point corresponding to the centre of the pupil1 and thus form an angle1 as seen in fig4 #bb1 where the cones are omitted1 to avoid confusion2 this angle is the angle of vision4 ,now the size which objects appear to possess is measured by this angle1 or by the linear magnitude of their images 7i4 e4 their size estimated in one direction1 as of length or breadth7 upon the retina4 ,when the object is distant1 the angle and its linear magnitude are small1 and it appears small and distant2 whilst if it be large1 or if small and brought near the eye1 the reverse will be the case4 ,magnification4--,hence an object may be made to appear larger1 or may be magnified1 by increasing the linear magnitude of its image upon the retina1 which can be done by bringing it nearer the eye1 as shown in fig4 #bb1 where the image of b formed at b is larger than the image of a formed at a4 ,but when an object is brought nearer the eye than about #h or #aj inches 7for the distance varies with different persons71 its image becomes indistinct and misty2 and this because the rays composing the cones are too divergent to meet at a focus upon the retina1 as shown in fig4 #bc4 ,by interposing a convex lens1 however1 between the eye and the object1 the too divergent rays may be made to meet at a focus upon the retina1 as in fig4 #bd1 the object at the same time being rendered apparently larger or magnified1 from the refracting action of the lens upon the cones4 ,aplanatism 7a1 not1 1 to wander74--,the effect of spherical aberration in rendering the image of an object seen through a lens indistinct and misty may now be intelligible4 ,in order that such image may be distinct1 the rays emanating from each point of the object must converge at one spot upon the retina4 ,but since1 when spherical aberration exists1 the marginal rays are more refracted than the central ones1 they will meet at foci before those formed by the latter2 and when the foci of one set are coincident with the retina1 so that the image would otherwise be distinct1 the latter is rendered confused and indistinct by the rays of the other set4 ,in this consideration1 we imply that there are only two sets of rays1 the central and the marginal2 but the central and marginal rays are not separate1 for the rays possess every intermediate degree of obliquity1 hence the foci and images are really innumerable4 ,now there are evidently two methods of destroying or correcting spherical aberration1 viz4 by excluding the marginal rays1 or by altering their direction4 ,the exclusion of the marginal rays is often adopted2 and is effected by means of a diaphragm1 or stop as it is called4 ,this consists of a plate of metal1 with a round aperture in the middle1 and it is placed behind the lens2 but it has the serious defect of diminishing considerably the amount of light transmitted4 ,the alteration of the direction of the marginal rays is produced by refraction1 a thin plano-concave lens being placed in front of the convex one 7,pl4 ,,xii4 fig4 #be74 ,the doubly convex lens is composed of crown glass1 and the concave lens of flint glass1 which has a higher refractive and dispersive power than crown glass4 ,in this way we get a compound lens1 which1 if the two lenses had the same refractive power1 would simply amount to a plano-concave lens with the marginal portions removed4 ,but as the concave lens consists of more highly refracting material than the convex1 if the curve and thickness of the two lenses be properly adapted1 the marginal portions of the concave correct the too great convergence of the marginal rays produced by the convex lens1 and so the rays are brought to nearly the same focus4 ,an idea of this action may be obtained from fig4 #be1 the dotted lines indicating the direction which the rays would take1 if passing through the convex lens only4 ,a lens in which the spherical aberration is corrected is said to be aplanatic4 ,achrmatism4--,supposing the spherical aberration of a lens to be corrected1 there still remains the chromatic aberration 7p4 #agc72 for although the central or mean coloured rays may meet at a focus1 the other coloured rays belonging to the same compound or ordinary ray will meet at different foci1 so that a series of coloured images of the object will be formed at different distances from the lens2 hence1 at whichever focus the object is viewed1 it will appear coloured4 ,now the coloured primary rays can only be made to coincide in direction1 so that the light parts of an object may appear white1 by refraction4 ,and the correction is produced by the same plano-concave lens as that which corrects the spherical aberration4 ,but in this case the relative dispersive powers of the media composing the convex and the concave lenses form the point to be considered4 ,if the dispersive power of the media of which the convex and concave lenses are composed were the same1 the dispersive power of the convex lens would be in excess1 and the coloured rays in each compound ray could not become parallel4 ,but by forming the concave lens of a more highly dispersive medium1 with a less proportional mean refraction than the convex1 when the curves of the surfaces and the relative thickness of the lenses are properly adjusted1 the dispersive action of the concave lens may be made equal to that of the convex2 and being exerted in the opposite direction1 the coloured rays will become parallel and meet at a single focus4 ,this may be elucidated by considering the lenses as composed of prisms4 ,thus1 let fig4 #bh represent the compound lens1 the two halves of the doubly convex lens acting as two triangular prisms 7fig4 #ai7 with their bases opposed1 converging the compound white rays w w1 and dispersing the coloured elementary rays1 which would form spectra at s s4 ,in the plano-concave lens the triangular prisms may be considered as placed with their apices towards each other1 and so would tend to disperse the coloured rays in the opposite direction1 to form spectra at t t4 ,then1 supposing the dispersions to be equal and in opposite directions1 the coloured rays would become parallel and meet at a definite focus1 the colour being destroyed4 ,at the same time1 the spherical action of the concave lens being opposite to that of the convex1 the converging action of the latter will be diminished1 so that the focus of the compound lens will be longer than that of the convex alone2 but as the dispersive power of the concave is greater relatively than that of the convex1 the mean refraction is less altered than the refraction or dispersion of the separate coloured rays2 so that the concave wholly opposes or corrects the dispersion produced by the convex1 while it only partially corrects its mean refraction4 ,a lens in which the chromatic and spherical aberrations are corrected or destroyed is commonly called achromatic2 although the term properly applies to the correction of the colour only4 ,if in a compound lens the chromatic aberration is only partially corrected1 so that the red rays still meet at a focus beyond the violet1 as in a simple uncorrected lens 7fig4 #bj71 the lens is said to be under-corrected1 or the aberration to be positive2 while if the correcting action of the plano-concave lens be too great1 so that the violet rays meet before the red1 as in a simple concave lens1 the lens is said to be over-corrected1 and the aberration is called negative4 ,although the positive chromatic aberration of the extreme rays passing through a convex lens may be corrected by the negative aberration of a concave lens1 there still remains a certain amount of uncorrected colour1 arising from the irrationality of the spectra of the two refracting media4 ,this evil cannot be overcome1 and the remaining colour is said to arise from the secondary spectrum4 ,the object-glasses of the microscope1 consisting of the compound lenses1 have their aberrations balanced to a considerable extent on the above principles--the lowest combination being under-corrected1 while the upper combinations are over-corrected2 and1 by suitable adaptation of their distance from each other1 further correction may be obtained1 the aberration of the object-glass altogether being1 however1 over-corrected or negative4 ,the eye-piece consists of two simple plano-convex lenses1 the upper or eye-glass 7fig4 #bg e7 having a shorter focus than the lower 7f7 or field-glass1 and the two placed at the distance of half the sum of their focal lengths4 ,the object-glass alone would form an enlarged and reversed image of the object within the body of the microscope1 the cones of rays from each point of the object terminating at the larger arrows in the figure 7fig4 #bg74 ,but the rays meeting the field-glass are brought by it to a focus at the position of the smaller arrows1 where they form a reduced image2 and1 subsequently passing through the eye-glass1 they are so altered in direction as to enter the eye at a greater angle1 and to present a magnified image of the object4 ,the eye-piece produces several important effects4 ,the refraction being produced by two less convex lenses instead of one of greater convexity1 the spherical aberration is considerably reduced2 and the convexities of the lenses in the eye-piece being situated in an opposite direction to that of those in the object-glass1 the spherical aberration of the former reverses and so neutralizes that of the latter4 ,also the under-correction of the field-glass compensates the over-correction of the object-glass--the blue rays which are refracted more than the red by the field-glass1 being thrown upon the eye-glass nearer its centre1 where the refraction is less1 and thus the coloured rays become parallel or nearly so on reaching the eye4 ,moreover the field-glass collects a larger number of rays than the eye-glass could do alone1 so that it enlarges the field and increases its brightness4 ,in the best object-glasses the aberrations are so well balanced that the mere covering an object with thin glass is sufficient to disturb the balance and render very delicate markings either misty and coloured or wholly invisible4 ,the effect produced by a plate of glass may be understood by reference to fig4 #bf1 the rays being supposed to emanate from the object at a2 and it is evident that the refraction of the glass so alters the direction of the rays that they will fall upon the lower combination nearer the centre than if the cover were absent1 and thus negative aberration is produced4 ,in the best object-glasses1 however1 this aberration may almost entirely be removed1 the lower combination being susceptible of approximation by a screw movement to the second or next above it1 so that the ascending rays1 being able to continue their oblique course through the increased distance between the object and the lower combination1 may fall upon the same portions of the latter that they did before the cover was applied4 ,,polarization ,,of ,,light4--,in attempting to give a sketch of this curious and difficult subject1 we must suppose the reader to be in possession of a natural crystal of calcareous spar1 and either two ,nicol's prisms 7forming the ordinary polariscope7 or two plates of the mineral called tourmaline cut in the direction of the length or axis of the crystal4 ,hitherto we have considered rays of light falling upon transparent substances as simply refracted or reflected according to the ordinary laws of refraction or reflexion4 ,we have now to notice some curious exceptions1 forming the basis of many interesting phenomena1 especially in connexion with the microscope1 in which these laws are more or less deviated from4 ,if we place a plate of tourmaline1 cut as above directed1 upon or beneath the stage of the microscope1 the light will pass through it1 appearing tinged with the green or brown colour natural to the tourmaline2 but on laying another slice upon the eye-piece1 and turning the latter round or rotating it1 the light will be transmitted in certain positions only1 being partially or entirely arrested in others1 so that the field appears black4 ,and1 on careful examination1 it will be noticed that the change from black to white occurs at each quarter of a rotation1 being twice black and twice white in an entire rotation1 the changes occurring alternately4 ,the same phenomena may also be exhibited by substituting two ,nicol's prisms for the tourmalines4 ,again1 if we take a natural crystal of calcareous spar1 and paste upon one side of it a piece of black paper with a small hole in the middle1 on holding the crystal to the light or over a piece of white paper1 with the covered side next the light1 two holes or two images of the hole will be seen2 and if the crystal without the paper be placed over some print1 the print will appear double4 ,hence the light passing through the hole is twice or doubly refracted1 one ray following the ordinary law of refraction1 while the other follows a different law1 being retarded and pursuing a longer course2 and so the two rays are called respectively the ordinary and extraordinary ray4 ,and on viewing these through a tourmaline or a ,nicol's prism1 as in the experiment with the two tourmalines1 the images will become alternately visible and invisible1 just as was then the case with the entire mass of light4 ,the light which has undergone this singular change is said to be polarized1 because the rays appear to have acquired poles or sides4 ,in the above experiments the lower prism or tourmaline is called the polarizer1 because it polarizes the light1 and the upper is called the analyzer1 because it analyzes or tests the light altered by the former4 ,an idea of the cause of this change may be obtained by reference to the undulatory theory of light4 ,ordinary light consists of waves or undulations taking place in planes at right angles to each other1 or in all planes2 while in polarized light the undulations are all in one plane or in parallel planes4 ,this may perhaps be understood by considering that books in a book-case are situated in parallel planes1 the shelves being in planes at right angles to the former4 ,and by imagining in polarizing substances the existence of some structure acting like a grating1 a notion can be obtained how the rays in the different planes may be transmitted or intercepted4 ,if the grating be so placed that the bars 7representing the planes of polarization7 are perpendicular1 the books can pass between them2 while if the grating be turned round a quarter of a circle1 they will become transverse1 and the books cannot pass1 while the shelves could do so4 ,carrying on this analogy1 the tourmaline or ,nicol's prism polarizes the light by transmitting only those rays whose undulations are in planes parallel to the bars2 while the analyzer allows these undulations to pass through it when the direction of the planes coincides with that of the bars1 but interrupts them when their direction is at right angles to the bars4 ,and it is evident that the planes of polarization of the ordinary and extraordinary rays are opposite1 from the opposite action of the analyzer upon them4 ,the power of doubly refracting and polarizing is not possessed by all crystalline bodies1 but only those belonging to other than the cubic system2 crystals belonging to this system neither doubly refract nor polarize light4 ,in all doubly refracting crystals there are one or more lines or directions in which the light is not doubly refracted4 ,these are called the optic axes1 and sometimes they coincide with the geometric axis of the crystals1 at others they do not2 and they may be regarded as positions or directions of equilibrium of certain molecular forces existing within the crystal1 which1 acting in opposition1 neutralize each other4 ,if light1 polarized by the polarizer1 be transmitted through thin doubly refracting crystals1 and analyzed by the analyzer1 splendid colours will become visible2 and on rotating separately either the polarizer or the analyzer1 at each quarter rotation the colours will change1 being complementary to those at first visible1 or such as are requisite with the first to make white light4 ,we have seen 7fig4 #ai7 that white light consists of seven coloured rays1 or of three primary colours--red1 yellow1 and blue1 which1 by superposition1 form the others2 and thus red is complementary to green1 which consists of blue and yellow1 the two sets of complementary colours appearing and vanishing as the light and darkness did when the crystals were not used4 ,these colours are produced by interference4 ,the compound rays of white light 7fig4 #cj l7 passing through the polarizer 7t7 are all polarized in one plane2 the crystal 7d7 depolarizes this light1 i4 e4 doubly refracts and resolves it into two sets of rays polarized in planes at right angles to each other1 forming the ordinary1 ,o1 and the extraordinary ray1 ,e4 ,each of these two sets of rays is resolved by the analyzer 7s7 into two other sets1 polarized in planes at right angles to each other2 so that in all there are four sets1 two in one plane and two in the other2 and1 the primary rays of the two sets in each plane being in different stages or phases of undulation1 in consequence of the retardation of the extraordinary rays1 the undulations of certain coloured rays check and annihilate each other1 while the remainder or complementary conspire and pursue their course1 producing the appearance of colour1 this effect being reversed at each quarter-revolution of the analyzer4 ,an idea of what is meant by phases of undulation may be obtained by reference to fig4 #bi1 in which the undulations1 a1 b1 are in similar states or phases1 and so conspire in action1 while the wave c is in a different phase and half an undulation behind the others2 hence it would check or interfere with either of the other waves 7a1 b71 the etherial molecules of the two1 which vibrate perpendicularly or at right angles to the direction of the wave1 acting to the same extent and in opposite directions4 ,in fig4 #cj the analyzer is represented as composed of a natural crystal 7rhomb7 of calcareous spar1 which transmits both sets of rays2 but in the ordinary analyzer or ,nicol's prism--which is made by dividing a rhomb through the obtuse angles into two wedge-shaped pieces and cementing them together again with balsam1 only one set of rays is transmitted at each quarter-revolution1 the other being refracted out of the field4 ,in the case of the tourmaline1 one of the sets of rays is absorbed2 so that the tourmaline1 like the ,nicol's prism1 is single-imaged4 ,thus the colours produced by polarization are the same as those of the spectrum1 but separated in a different way1 both arising from the elementary coloured rays of the compound white light4 ,for while the spectral rays are separated by dispersive refraction1 the polarized coloured rays are separated by the interference and annihilation of some rays1 the remainder passing on to produce the colours4 ,when the position of the depolarizing crystal is such that the plane of the polarized light coincides with the direction of the optic axis or axes1 the light is not doubly refracted nor polarized in certain parts2 hence these parts appear white if the plane of the polarizer and analyzer coincide1 and black if they be crossed4 ,a crystal cut at right angles to its optic axis1 with its length directed towards the polarizer and analyzer1 is in this position1 and it exhibits alternately a black and white cross1 with one or two sets of concentric rings of complementary colours at each quarter of a rotation4 ,to prepare crystals for examination by polarized light1 a little ,epsom salt1 nitre1 or borax should be dissolved in water1 a drop placed upon a slide1 and dried at a gentle heat4 ,the crystals should then be mounted in balsam1 and viewed as transparent objects4 ,to see the cross and rings1 the crystals should be sawn or cut across transversely1 the ends being polished on a strained piece of silk moistened with water1 and the sections mounted in balsam4 ,the property of doubly refracting and polarizing light is not confined to crystalline substances1 being also possessed by many organic bodies1 for the details of which ,i must refer to the article ,polarization in the #8,micrographic ,dictionary4' ,,index4 ,abdomen1 #abi4 ,aberration1 chromatic1 #agc4 ,aberration1 spherical1 #agb4 ,acaleph1 #aec4 ,acarus1 #aca4 ,accumbent1 #dd4 ,achromatic1 #agh4 ,achromatic condenser1 #e4 ,achromatism1 #agg4 ,acicular1 #bd4 ,acotyledons1 #dc4 ,acrocarpi1 #ee4 ,acrostalagmus1 #aaa4 ,actinocyclus1 #hj4 ,actinophrys1 #aef4 ,adapter1 #b4 ,adulteration1 #bc4 cidium1 #ajj4 ,agaricus1 #ig4 ,albumen1 of seeds1 #dc4 ----1 of eggs1 #aac4 ,alg1 #fd4 ,alyscum1 #afa4 ,amba1 #aee4 ,amphileptus1 #afb4 ,angiocarpi1 #id4 ,angle of vision1 #age4 ,anguillula1 #aeb4 ,angular1 #bc4 ,animal tissues1 #aac4 ,ankistrodesmus1 #gd4 ,annular vessels1 #bg4 ,annulus1 of ,ferns1 #ej4 ----1 of ,fungi1 #ih4 ----1 of ,mosses1 #ee4 ,anoplura1 #ace4 ,ant1 #adc4 ,antenn1 of ,entomostraca1 #abg4 ,antennaria1 #aaa4 ,anthers1 #cg1 #ci4 ,antheridia1 of ,alg1 #fe4 ----1 of ,ferns1 #eb4 ,antheridia1 of ,mosses1 #fa4 ,anthophysa1 #afj4 ,antlia1 #ade4 ,apex1 #cg4 ,aphis1 #adf4 ,apiculate1 #aja4 ,aplanatic1 #agg4 ,aplanatism1 #agf4 ,apothecia1 #ib4 ,apple-pulp1 #ai4 ,apple1 skin of1 #da4 ,arachnida1 #acj4 ,arcella1 #aef4 ,archegonia1 of ,ferns1 #eb4 ----1 of ,mosses1 #fb4 ,arcuate1 #gh4 ,areol1 #aaf4 ,areolar tissue1 #aaf4 ,arrow-root1 #bc4 ,arteries1 #aad4 ,articulata1 #abg4 ,asci1 of ,fungi1 #ig4 ----1 of ,lichens1 #ib4 ,ascomycetes1 #ajg4 ,ash1 #be4 ,aspergillus1 #ajf4 ,aspidium1 #ej4 ,astasia1 #afj4 ,atropos1 #ade4 ,bacterium1 #hf4 ,balsam1 garden-1 #be4 ----1 ,canada1 #ab4 ,bark1 #cf4 ,basidia1 #ih4 ,bast1 #bf4 ,batrachosperme1 #gb4 ,batrachospermum1 #gb4 ,beards of ,oyster1 #abe4 ,bee1 #adc4 ,beetles1 #adf4 ,bermuda deposit1 #ha4 ,bipinnatifid1 #ej4 ,bivalve1 #abh4 ,blood1 #aad4 ----1 of ,birds1 #aai4 ----1 of ,fishes1 #aba4 ----1 of ,reptiles1 #abj4 ,blood-corpuscles1 #aaa4 ,blood-worm 7,chironomus71 #adc4 ,blue-bottle1 #acg4 ,blue mould1 #ajf4 ,bone1 of ,birds1 #aai4 ----1 of ,reptiles1 #abj4 ----1 of ,mammals1 #aad4 ,bordered dots1 #bh4 ,bothrenchyma1 #bh4 ,botrytis1 #aje4 ,branchi1 #abe4 ,bread1 #bc4 ,bryozoa1 #abe4 ,bryum1 #ei4 ,buds1 #dg4 ,bug1 #ade4 ,bull's-eye1 #f4 ,bunt1 #ajb4 ,butterflies1 #add4 ,cabbage-butterfly1 #ade4 ,calicium1 #id4 ,calyptra1 #ee4 ,calyx1 #cg4 ,calcareous1 #ff4 ,camera lucida1 #ah4 ,campylodiscus1 #gh4 ,canaliculi1 #aae4 ,cancelli1 #aad4 ,capillaries1 #aad4 ,capillary1 #fi4 ,carapace1 #abg4 ,caraway1 #da4 ,carpels1 #da4 ,cartilage1 #aae4 ,caterpillars1 #ade4 ,cell-contents1 #ba4 ,cell-formation1 #bi4 ,cells1 #ai4 ,cell-wall1 #ai4 ,cellular tissue1 animal1 #aaf4 ---- tissue of plants1 #bj4 ,cement1 #af4 ,cephalothorax1 #acj4 ,ceramiace1 #fi4 ,ceramidia1 #ff4 ,ceramium nodosum1 #fi4 ---- rubrum1 #gj4 ,cercomonas1 #aei4 ,chtomium1 #aaj4 ,chtophorace1 #ga4 ,chara1 #hh4 ,cheese-mite1 #aca4 ,chelate1 #aca4 ,chickweed1 #cg4 ----1 seeds of1 #db4 ,chilodon1 #afb4 ,chin of ,insects1 #adg4 ,chironomus1 #adc4 ,chitine1 #acf4 ,chloride of calcium1 #ae4 ,chlorococcum1 #hg4 ,chlorophyll1 #ba4 ,chrysalis1 #ada4 ,chrysanthemum1 #be4 ,cilia1 #eb1 #aeg4 ,circulation in ,plants1 #ca4 ,cladonia1 #ic4 ,cladophora1 #ga4 ,classification1 #afd4 ,clavarini1 #ii4 ,clavate1 #adg4 ,closterium1 #gd4 ,coarse movement1 #b4 ,coccidia1 #fi4 ,coccinella1 #adg4 ,cocconeis1 #gi4 ,cocoa-nut fibre1 #bf4 ,clenterata1 #aec4 ,coleochte1 #gb4 ,coleoptera1 #adf4 ,coleps1 #afc4 ,collomia1 seeds of1 #db4 ,colpoda1 #afa4 ,columella1 of ,mosses1 #fb4 ----1 of ,mucor1 #aaa4 ,complementary colours1 #ahc4 ,compound animals1 #abf4 ,concentric1 #aad4 ,conceptacles1 of ,alg1 #fe4 ,conduplicate1 #dd4 ,conferva bombycina1 #ga4 ---- floccosa1 #ga4 ,confervace1 #gj4 ,confervoide1 #gj4 ,conidia1 #ajj4 ,conifer1 #bf4 ,coniomycetes1 #ii4 ,conjugation1 #gc4 ,continuous1 #ajc4 ,convolvulus1 pollen of1 #ci4 ,coral1 #aec4 ,corallina1 #ff4 ,corallinace1 #ff4 ,corallines1 #ff4 ,coremium1 #ajf4 ,corolla1 #cg4 ,coscinodiscus1 #ha4 ,cotton1 #aah4 ,cotton-plant1 #cc4 ,cotyledons1 #dc1 #dd4 ,covers1 #f4 ,coxa1 #aci4 ,crenate1 #ej4 ,crocus1 pollen-tubes of1 #dj4 ,crucifer1 #dd4 ,crustacea1 #abg4 ,crustaceous1 #ia4 ,cryptogamic plants1 #dh4 ---- ----1 seeds of1 #dc4 ,ctenoid1 #aba4 ,cucumber1 #db4 ,culex1 #ada4 ,culm1 #cd4 ,cuneate1 #gi4 ,cup-moss1 #ic4 ,curculionid1 #adi4 ,cycloid1 #aba4 ,cyclops1 #abh4 ,cypris1 #abh4 ,dacrymyces1 #ii4 ,daphnia1 #abi4 ,dasya1 #fh4 ,day-flies1 #ade4 ,deal1 #bf4 ,delesseria1 #fi4 ,dematiei1 #ajd4 ,desmidiace1 #gc4 ,diamond-beetles1 #adi4 ,diaphragm1 #c4 ,diatoma1 #gh4 ,diatomace1 #ge4 ----1 fossil1 #hb4 ----1 markings on1 #ha4 ----1 preparation of1 #hb4 ,dichotomous1 #fg4 ,dicotyledons1 leaves of1 #ce4 ----1 seeds of1 #dc4 ----1 stems of1 #ce4 ,dicranum1 #eg4 ,differentiation1 #dg4 ,dimidiate1 #ee4 ,dinobryina1 #afj4 ,dinobryon1 #afj4 ,dicious1 #ch4 ,dipping-tubes1 #d4 ,diptera1 #acg4 ,dispersion1 #agh4 ,division1 spontaneous1 #aei4 ,dothidea1 #ajh4 ,dragon-flies1 #ade4 ,draparnaldia1 #ga4 ,dry rot1 #ih4 ,ducts1 #bg4 ,dung-beetle1 #acb4 ,dytiscus1 #adh4 ,eccremocarpus1 seeds of1 #db4 ,echinodermata1 #aec4 ,echinus1 #aec4 ,elbowed1 #adi4 ,elder1 #be4 ,elements1 vegetable1 #ai4 ,elytra1 #adg4 ,emarginate1 #adf4 ,embryo1 #db4 ,embryo-sac1 #df4 ,embryonal vesicles1 #df4 ,enchelys1 #afa4 ,encysting1 #aei4 ,endogenous1 #bi4 ,endogens1 leaves of1 #ce4 ----1 seeds of1 #dd4 ----1 stems of1 #dd4 ,enteromorpha1 #hg4 ,entomostraca1 #abg4 ,entozoa1 #aea4 ,ephemera1 #ade4 ,epidermis1 animal1 #aag4 ----1 vegetable1 #ca4 ,epithemia1 #gg4 ,equisetum1 #cd4 ,erector1 #e4 ,erysiphe1 #aaj4 ,euglena1 #afj4 ,excipulum1 #ib4 ,excurrent1 #eg4 ,exogenous1 #bi4 ,exogens1 leaves of1 #ce4 ----1 seeds of1 #dc4 ----1 stems of1 #ce4 ,eye-pieces1 #d1 #agi4 ,eyes1 compound1 #ach4 ,facets1 #ach4 ,favell1 #gj4 ,feathers1 #aai4 ,feathery1 #abg4 ,femur1 #aci4 ,ferns1 #di4 ----1 reproduction of1 #ea4 ,fertilization1 #de4 ,fibro-cellular tissue1 #be4 ,fibro-vascular tissue1 #ca4 ,field1 #g4 ,filament1 #cg4 ----1 flagelliform1 #aei4 ,fine movement1 #b4 ,fish-crystals1 #abb4 ,flagelliform1 #aei4 ,flax1 #bf1 #aah4 ,flea1 #acf4 ,flocci1 #ajc4 ,floride1 #ff4 ,floscularia1 #aea4 ,flowers1 #cg4 ,flustra1 #abf4 ,fly1 #ach4 ,fly-blows1 #aci4 ,focus1 #aga4 ,foot-jaws1 #abg4 ,foramen1 #de4 ,foramina1 #aad4 ,foraminifera1 #aef4 ,forceps1 #d4 ,forked veins1 #ej4 ,fovilla1 #afj4 ,fragilaria1 #gh4 ,fronds1 #di4 ,fruit1 #dj4 ,frustules1 #ge4 ,fucoide1 #fd4 ,fucus1 #fe4 ,fulcra1 #aaj4 ,funaria1 #eh4 ,fungi1 #if4 ,funiculus1 #de4 ,fusiform1 #aaj4 ,galls1 #aaa4 ,gamasus1 #acb4 ,gasteromycetes1 #ii4 ,gemmation1 #aei4 ,gentles1 #adj4 ,geranium1 leaf of1 #ba4 ----1 petals of1 #bj1 #ch4 ,germinate1 #dc4 ,gills1 of ,fungi1 #ig4 ----1 of ,mollusca1 #abe4 ,glands1 #dj4 ,glandular1 #ca4 ---- tissue1 #bf4 ,glocapsa1 #hh4 ,glumes1 #cg4 ,glycerine1 #ad4 ,gnats1 #ada4 ,gomphonema1 #gi4 ,gonidia1 of ,alg1 #ga4 ----1 of ,lichens1 #ib4 ,gonium pectorale1 #hc4 ---- tranquillum1 #hd4 ,grape-,fungus1 #aje4 ,graphis1 #id4 ,green fly1 #adf4 ,gristle1 #aae4 ,groundsel1 #cc4 ,guard-cells1 #cd4 ,gymnocarpi1 #id4 ,gymnostomum1 #ef4 ,gyrosigma angulatum1 #hj4 ---- attenuatum1 #gi4 ,hairs1 #ca4 ----1 animal1 #aag4 ,hart's-tongue ,fern1 #ea4 ,harvest-bug1 #acb4 ,haversian canals1 #aad4 ,helvellacei1 #ajg4 ,hemiptera1 #ade4 ,hemp1 #bf4 ,hermaphrodite1 #ch4 ,heteromita1 #afj4 ,hilum1 #bb4 ,hoop1 #gf4 ,humble ,bee1 #add4 ,hundred-legs1 #acc4 ,hyalotheca1 #gd4 ,hydnei1 #ii4 ,hydra1 #aec4 ,hymenium1 #ih4 ,hymenomycetes1 #ig4 ,hymenoptera1 #adc4 ,hyphomycetes1 #ajc4 ,hypnea1 #fi4 ,hypnum1 #fj4 ,hysterium1 #ajh4 ,illumination1 #h4 ,imago1 #ada4 ,imbricate1 #ef4 ,incumbent1 #dd4 ,indusium1 #ea4 ,inflated1 #aaj4 ,infusoria1 #aeg4 ,injection1 #aaf4 ,innovations1 #ee4 ,insects1 #acc4 ,intercellular passages1 #bj4 ,intercellular spaces1 #bj4 ,iodine1 #bb4 ,isaria1 #ajd4 ,jania1 #fg4 ,jaws1 of ,insects1 #adg4 ,joints1 of ,insects1 #acf4 ,jute1 #bf4 ,knife1 #d4 ,labels1 #ag4 ,labial palpi1 #acd4 ,labium1 #adg4 ,labrum1 #adg4 ,lacun1 #aae4 ,lady-bird1 #adg4 ,lanceolate1 #gh4 ,leaves1 #ca4 ,legs1 of insects1 #aci4 ,lenses1 #agj4 ,lentil1 #bc4 ,lepidoptera1 #add4 ,lepisma1 #acd4 ,liber1 #bf1 #ce4 ,lice1 #ace4 ,lichens1 #ia4 ,lieberkuhn1 #g4 ,light1 #afg4 ,lime1 #be4 ,lips1 of insects1 #adg4 ,lirell1 #id4 ,lithobius1 #acc4 ,lithocystis1 #fg4 ,live-box1 #d4 ,london pride1 anthers of1 #ci4 ,longitudinal1 #cj4 ,lunate1 #adg4 ,lyngbya1 #he4 ,magnification1 #age4 ,magnifying power1 #ag4 ,mammalia1 #aac4 ,mandibles1 of insects1 #adg4 ----1 of ,spiders1 #acj4 ,mantle1 #abc4 ,marrow1 #aad4 ,matrix1 #ia1 #if4 ,maxill1 #adg4 ,medium1 #afh4 ,medulla1 #ce4 ,medullary sheath1 #ce4 ,melanospore1 #fd4 ,melobesia1 #fg4 ,melosira1 #gi4 ,membrane1 #ca4 ,membranipora1 #abf4 ,mentum1 #adg4 ,merulius1 #ih4 ,micrasterias1 #gd4 ,micropyle1 of seeds1 #df4 ,microscope1 #a4 ----1 simple1 #e4 ,midrib1 #ej4 ,mignonette1 seeds of1 #db4 ,mildew1 #aja4 ,mirror1 #b1 #c4 ,mitriform1 #ee4 ,mollusca1 #abb4 ,monadina1 #aei4 ,monas1 #aei4 ,moniliform1 #ca4 ,monocotyledons1 leaves of1 #ce4 ----1 seeds of1 #dc4 ----1 stems of1 #cf4 ,moncious1 #ch4 ,mosses1 #ed4 ,moths1 #add4 ,mould of paste1 #aaa4 ,moulds1 #if4 ,mounting1 #aj4 ,mouth of insects1 #adg4 ,mucedines1 #aje4 ,mucor1 #aaa4 ,muscles1 #aae4 ,mushroom1 #ig4 ,mustard and cress1 #dc4 ----1 cotyledons of1 #dd4 ,mycelium1 #if4 ,myriapoda1 #acc4 ,nacre1 #abc4 ,nassula1 #afb4 ,needles1 mounted1 #d4 ,nemaspora1 #ajj4 ,nerves1 of leaves1 #ca4 ,neuroptera1 #ade4 ,newt1 #abj4 ,nicol's prism1 #f1 #ahd4 ,nitella1 #hh4 ,nitzschia1 #gh4 ,nodding1 #ei4 ,nodule1 #gi4 ,nostoc1 #hf4 ,nucleolus1 #ba4 ,nucleus1 #ba4 ----1 of ,infusoria1 #aei4 ----1 of ovule1 #de4 ,oak-apple1 #aaa4 ,oat1 #bc4 ,object-glasses1 #b4 ,oblique1 #cj4 ---- light1 #i4 ,obovate1 #eg4 ,obtuse1 #ej4 ,ocelli1 of ,spiders1 #acj4 ,oidium1 #aje4 ,opegrapha1 #id4 ,operculum1 #ee4 ,optic axes1 #ahc4 ,orange1 rind of1 #dj4 ,organs1 vegetable1 #ca4 ,oscillatoria autumnalis1 #hd4 ---- nigra1 #he4 ,oscillatoriace4 #hd4 ,ovary1 of animals1 #acg4 ---- of plants1 #cg1 #dj4 ,ovate1 #ef4 ,ovigerous vesicles1 #aed4 ,ovisacs1 #aed4 ,ovules1 #de4 ,ovum1 #aac4 ,oxytricha1 #afa4 ,oyster-shell1 #abc4 ,pale1 #cg4 ,palmella1 #hh4 ,palmellace1 #hg4 ,palpi1 of insects1 #adg4 ,papilla1 #ci4 ,papill1 of skin1 #aaf4 ,papillose1 #ci4 ,paramecium1 #afa4 ,paraphyses1 #fa4 ,parenchyma1 #bj4 ,parmelia1 #ia4 ,pear1 #bi4 ,pearls1 #abc4 ,pectinate1 #fi4 ,pediastrum1 #gd4 ,pedicels1 #ajc4 ,pencil1 #abh4 ,penicillium1 #ajf4 ,perianth1 #cg4 ,pericarp1 #dj4 ,perichtial1 #fj4 ,peridiola1 #aaj4 ,peridium1 #ii1 #ajj4 ,perigonial1 #fa4 ,perispore1 #fe4 ,peristome1 #ee4 ,perithecium1 #ajg4 ,petals1 #cg1 #ch4 ,peziza1 #ajg4 ,phases1 #ahd4 ,phragmidium1 #aja4 ,physarum1 #ii4 ,physomycetes1 #aaj4 ,pigment1 #aag4 ,pileus1 #ig4 ,pinn1 #ea4 ,pinnate1 #ea4 ,pinnatifid1 #ej4 ,pinnularia1 #gi4 ,pinnules1 #ea4 ,pistil1 #cg4 ,placenta1 #de4 ,pleurenchyma1 #bf4 ,pleurocarpi1 #ee4 ,pleurosigma1 #gi4 ,plocamium1 #fi4 ,plumose1 #abg4 ,plum-stone1 #bi4 ,plumule1 #dc4 ,podetia1 #ic4 ,podophrya1 #afb4 ,podura1 #acd4 ,polariscope1 #f4 ,polarization of light1 #ahj4 ,pollen1 #cg4 ,pollen-granules1 #ci4 ,pollen-tubes1 #dj4 ,polycystina1 #aef4 ,polypi1 #aec4 ,polypidom1 #abe4 ,polypodiace1 #ej4 ,polypodium1 #ej4 ,polyporei1 #ii4 ,polysiphonia1 #fh4 ,polytrichum1 #eh4 ,polyzoa1 #abf4 ,polyzoary1 #abf4 ,poppy1 seeds of1 #db4 ,pore1 #aji4 ,pores1 in wood1 #bh4 ,porous cells1 #be4 ,potato1 #bb4 ,potato-fungus1 #aje4 ,primine1 #de4 ,primordial utricle1 #ba4 ,primrose1 pollen of1 #ci4 ,prismatic1 #bd4 ,proboscis1 #adf4 ,prolegs1 #ade4 ,prosenchyma1 #be4 ,prothallium1 #ea4 ,protoplasm1 #ba4 ,protozoa1 #aee4 ,pterodina1 #aea4 ,puccinia1 #aja4 ,puff-balls1 #ii4 ,pulex1 #ace4 ,pulvilli1 #aci4 ,puncta1 #gi4 ,pupa1 #ada4 ,quadrate1 #adg4 ,racodium1 #aaa4 ,radiata1 #aec4 ,radicle1 #dc4 ,ramenta1 #di4 ,raphides1 #bd4 ,receptacles1 of ,alg1 #fe4 ----1 of secretion1 #dj4 ,red ,spider1 #acb4 ,reflexion1 #afi4 ,refraction1 #afh4 ,reindeer moss1 #ic4 ,reproductive organs1 #dh4 ,reptiles1 #abj4 ,resting spores1 #hc4 ,reticulated1 #ed1 #abi4 ---- vessel1 #bg4 ,rhabdonema1 #hj4 ,rhinotrichum1 #ajg4 ,rhizome1 #di4 ,rhizopoda1 #aee4 ,rhodomelace1 #fg4 ,rhodosperme1 #ff4 ,rhodymeniace1 #fi4 ,rhubarb1 #be4 ,rice1 #bc4 ,richmond earth1 #hb4 ,rings1 annual1 #cf4 ,roe of fishes1 #abb4 ,rootlets1 #cf4 ,roots1 #cf4 ,rostrate1 #ef4 ,rostrum1 #aca4 ,rotating disk1 #f4 ,rotation1 #ca4 ,rotatoria1 #adi4 ,rotifer1 #aej4 ,rotifera1 #adi4 ,sacculi1 gastric1 #aeh4 ,san ,fiori deposit1 #hb4 ,sarcode1 #aee4 ,scalariform ducts1 #di4 ,scales1 of fishes1 #aba4 ----1 of ,podura1 #acd4 ----1 of insects1 #add4 ,scar of seeds1 #df4 ,scenedesmus1 #gd4 ,schizogonium1 #hf4 ,scolopendrium1 #ea4 ,sea-weeds1 #fd4 ,sections1 #cj4 ,secundine1 #de4 ,seeds1 #db4 ,selenite1 #bd4 ,sepals1 #cg4 ,septa1 #ii4 ,septate1 #ajj4 ,serrate1 #ea4 ,sertularia1 #aed4 ,sessile1 #ed4 ,setaceous1 #acc4 ,set1 #abi4 ---- of ,infusoria1 #aeh4 ,shell1 #abb4 ,side condenser1 #f4 ,silk1 #aah4 ,simple microscope1 #e4 ,sines1 #afh4 ,siphonace1 #hd4 ,skin1 #aaf4 ,slides1 #f4 ,smut1 #ajb4 ,snapdragon1 petals of1 #ci4 ,snowberry1 #db4 ,sori1 of ,ferns1 #ej4 ,spawn1 of ,fungi1 #ig4 ,spectrum1 #agc4 ,spermatia1 #ic4 ,spermatozoa1 of ,alg1 #fe4 ----1 of ,ferns1 #eb4 ----1 of ,fishes1 #abb4 ----1 of ,mosses1 #fa4 ,spermogonia1 of ,fungi1 #aja4 ----1 of ,lichens1 #ib4 ,sphria1 #aji4 ---- fragiformis1 #ajd4 ,sphagnum1 #ef4 ,spicula1 #aeg4 ,spiders1 #acj4 ,spiderwort1 #ca4 ,spinnerets1 #aca4 ,spiracles1 #acd4 ,spiral cells1 #be4 ,spiral vessels1 #bg4 ,spirit-lamp1 #e4 ,spirogyra1 #gb4 ,spirulina1 #he4 ,sponges1 #aef4 ,spongid1 #aef4 ,sporangium1 of ,ferns1 #ed4 ,spores1 #ej4 ,sporocybe1 #ajd4 ,sporophylles1 #fi4 ,stage1 #b4 ,stamens1 #cg4 ,starch1 #bb4 ,starfishes1 #aec4 ,stellate1 #ca4 ,stems1 #ce4 ,stentor1 #afc4 ,sterigmata1 #ih4 ,steropus1 #adf4 ,stichidia1 #fh4 ,stigma1 #cg4 ,stilbacei1 #ajc4 ,sting1 of ,wasp1 #add4 ,stinging-organs1 #aed4 ,stings1 #cc4 ,stipes1 #gf1 #ig4 ,stomata1 #cd4 ,stomoxys1 #ada4 ,striated1 #cc4 ,stroma1 #ajh4 ,struma1 #eh4 ,style of plants1 #cg4 ,stylospores1 #ajj4 ,suctorial1 #ace4 ,suture1 #gc1 #gf4 ,synedra1 #gh4 ,synura1 #hc4 ,tabellaria1 #gi4 ,tabular1 #hc4 ,tangential1 #cj4 ,tape-worm1 #aeb4 ,tarsus1 #aci4 ,tentacles1 #abd1 #aec4 ,testa1 #db4 ,tetraspores1 #afg4 ,thalamium1 #ib4 ,thallus1 #ia4 ,thec1 #ej4 ,thorax1 #abi4 ,thread-worm1 #aeb4 ,tibia1 #aci4 ,tissues1 vegetable1 #ai4 ,toad-stools1 #if4 ,tongue1 of ,mollusca1 #abc4 ,tortula1 #eg4 ,torula1 #ajj4 ,tourmaline1 #aha4 ,tous les mois1 #bd4 ,trabecul1 #ei4 ,trache1 #acd4 ,trachelomonas1 #afj4 ,tradescantia1 #ca4 ,transverse1 #adh4 ---- section1 #cj4 ,tremellini1 #ii4 ,trichothecium1 #aje4 ,triton1 #abj4 ,trochanter1 #aci4 ,trombidium1 #acb4 ,truffle1 #ajh4 ,truncated1 #bg4 ,tuberacei1 #ajh4 ,tubercularia1 #ajc4 ,tuberculate1 #aja4 ,tubular cells1 #be4 ,tufts1 #be4 ,turnip-fly1 #adf4 ,turpentine1 #bg4 ,ulothrix1 #hf4 ,ulva1 #hg4 ,ulvace1 #hf4 ,umbellifer1 #da4 ,uncorrected lens1 #agh4 ,uniseptate1 #aja4 ,uredo1 #ajb4 ---- candida1 #ajb4 ---- caries1 #ajb4 ---- linearis1 #aji4 ---- rubigo1 #aji4 ---- segetum1 #ajb4 ,vaginicola1 #afc4 ,vaginule1 #fb4 ,valve1 #gf4 ,vascular tissue1 #bg4 ,vaucheria1 #hd4 ,vegetable elements1 #ai4 ---- organs1 #ca4 ,veil1 #ih4 ,veins1 of animals1 #aad4 ----1 of leaves1 #ca1 #ce4 ,velum1 #ih4 ,vertebra1 #aac4 ,vertebrata1 #aac4 ,vesicles1 contractile1 #aei4 ----1 embryonal1 #df4 ,vessels1 #bg4 ,vibrio spirillum1 #he4 ,vision1 #agd4 ,vitt1 of seeds1 #dj4 ,volva1 #ih4 ,volvocine1 #hc4 ,volvox1 #hc4 ,vorticella1 #afb4 ,wallflower1 anthers of1 #ci4 ,wasp1 #adc4 ,water-beetle1 #adh4 ,web1 spider's1 #aca4 ,wheat1 cotyledon of1 #de4 ,wheat-flour1 #bc4 ,wheel-animalcules1 #aej4 ,whelk1 #abc4 ,wine-cellar ,fungus1 #aaa4 ,winged seeds1 #db4 ,winter ova1 #abh4 ,wood-cells1 #be4 ,wood-louse1 #abg4 ,woody fibre1 #be4 ---- tissue1 #be4 ,wool1 #aah4 ,xanthidia1 #ge4 ,yeast1 #ajf4 ,zygnema1 #gb4 ,zygnemace1 #b4 ,zoospores1 #ga4 ,,taylor ,,and ,,francis1 ,,printers1 ,,red ,,lion ,,court1 ,,fleet ,,street4