,transcriber's note3 ,a few typographical errors have been corrected3 they are listed at the end of the text4 99 99 99 99 99 ,,the ,,mechanism ,,of ,,life ,illustration3 ,osmotic ,productions4 ,frontispiece ,,the ,,mechanism ,,of ,,life ,,by ,,dr4 ,,stephane ,,leduc ,,professeur ,a ,l',,ecole ,,de ,,medecine ,,de ,,nantes ,,translated ,,by ,w4 ,,deane ,,butcher ,,formerly ,,president ,,of ,,the ,,roentgen ,,society1 ,,and ,,of ,,the ,,electro-,,therapeutical ,,section ,,of ,,the ,,royal ,,society ,,of ,,medicine ,la nature a forme1 et forme tous les jours les etres les plus simples par generation spontanee4 ,,lamarck4 ,illustration ,,new ,,york ,,rebman ,,company ,,herald ,,square ,,building #ada-ade1 ,,west #cf,,th ,,street ,first ,impression ,march #aiaa ,second ,impression ,january #aiad ,printed in ,england 99 99 99 99 99 vii ,,translator',s ,,preface ,professor ,leduc's ,theorie ,physico-chimique de la ,vie et ,generations ,spontanees has excited a good deal of attention1 and not a little opposition1 on the ,continent4 ,as recently as #aijg the ,academie des ,sciences excluded from its ,comptes ,rendus the report of these experimental researches on diffusion and osmosis1 because it touched too closely on the burning question of spontaneous generation4 ,as the author points out1 ,lamarck's early evolutionary hypothesis was killed by opposition and neglect1 and had to be reborn in ,england before it obtained universal acceptance as the ,darwinian ,theory4 ,not unnaturally1 therefore1 he turns for an appreciation of his work to the free air and wide horizon of the ,english-speaking countries4 ,he has entitled his book ,the ,mechanism of ,life1 since however little we may know of the origin of life1 we may yet hope to get a glimpse of the machinery1 and perhaps even hear the whirr of the wheels in ,nature's workshop4 ,the subject is of entrancing interest to the biologist and the physician1 quite apart from its bearing on the question of spontaneous generation4 ,whatever view may be entertained by the different schools of thought as to the nature and significance of life1 all alike will welcome this new and important contribution to our knowledge of the mechanism by which ,nature constructs the bewildering variety of her forms4 ,there is1 ,i think1 no more wonderful and illuminating spectacle than that of an osmotic growth1--a crude lump of brute inanimate matter germinating before our very eyes1 putting forth bud and stem and root and branch and leaf and fruit1 with no stimulus from germ or seed1 without even viii the presence of organic matter4 ,for these mineral growths are not mere crystallizations as many suppose2 they increase by intussusception and not by accretion4 ,they exhibit the phenomena of circulation and respiration1 and a crude sort of reproduction by budding2 they have a period of vigorous youthful growth1 of old age1 of death and of decay4 ,they imitate the forms1 the colour1 the texture1 and even the microscopical structure of organic growth so closely as to deceive the very elect4 ,when we find1 moreover1 that the processes of nutrition are carried on in these osmotic productions just as in living beings1 that an injury to an osmotic growth is repaired by the coagulation of its internal sap1 and that it is able to perform periodic movements just as an animal or a plant1 we are at a loss to define any line of separation between these mineral forms and those of organic life4 ,in the present volume the author has collected all the data necessary for a complete survey of the mechanism of life1 which consists essentially of those phenomena which are exhibited at the contact of solutions of different degrees of concentration4 ,whatever may be the verdict as to the author's case for spontaneous generation1 all will agree that the book is a most brilliant and stimulating study1 founded on the personal investigation of a born experimenter4 ,the present volume is a translation of ,dr4 ,leduc's ,french edition1 but it is more than this1 the work has been translated1 revised and corrected1 and in many places re-written1 by the author's own hand4 ,i am responsible only for the ,english form of the treatise1 and can but regret that ,i have been able to reproduce so imperfectly the charm of the original4 ,w4 ,,deane ,,butcher4 ,,ealing4 99 99 99 99 99 ix ,,preface ,,to ,,the ,,english ,,edition ,c'est par l'initiative du ,dr4 ,deane ,butcher que cette ouvrage est presente aux lecteurs anglais1 a la race qui a dote l'humanite de tant de decouvertes originales1 geniales et d'une portee tres generale4 ,comme un etre vivant1 une idee exige pour naitre et se developper le germe et le milieu de developpement4 ,il est indeniable que le peuple anglo-americain constitue un milieu particulierement favorable a la naissance et au developpement des idees nouvelles4 ,pendant notre collaboration le ,dr4 ,deane ,butcher a ete un critique judicieux et eclaire1 tous les changements dans l'edition anglaise sont dus a ses observations4 ,il s'est assimile l'ouvrage pour le traduire1 et dans beaucoup de parties1 il a mis plus de clarte et de concision qu'il n'y en avait dans le texte original4 ,,stephane ,,leduc4 ,,nantes1 #aiaa4 99 99 99 99 99 xi ,,table ,,of ,,contents ,,page ,,translator',s ,,preface vii ,,author',s ,,preface ix ,,introduction xiii ,i4 ,,life ,,and ,,living ,,beings #a ,,ii4 ,,solutions #ad ,,iii4 ,,electrolytic ,,solutions #bd ,,iv4 ,,colloids #cf ,v4 ,,diffusion ,,and ,,osmosis #dc ,,vi4 ,,periodicity #fg ,,vii4 ,,cohesion ,,and ,,crystallization #gh ,,viii4 ,,karyokinesis #hi ,,ix4 ,,energetics #ig ,x4 ,,synthetic ,,biology #aac ,,xi4 ,,osmotic ,,growth3 ,a ,,study ,,in ,,morphogenesis #abc ,,xii4 ,,the ,,phenomena ,,of ,,life ,,and ,,osmotic ,,productions3 ,a ,,study ,,in ,,physiogenesis #adg ,,xiii4 ,,evolution ,,and ,,spontaneous ,,generation #afj 99 99 99 99 99 xiii ,,introduction ,life was formerly regarded as a phenomenon entirely separated from the other phenomena of ,nature1 and even up to the present time ,science has proved wholly unable to give a definition of ,life2 evolution1 nutrition1 sensibility1 growth1 organization1 none of these1 not even the faculty of reproduction1 is the exclusive appanage of life4 ,living things are made of the same chemical elements as minerals2 a living being is the arena of the same physical forces as those which affect the inorganic world4 ,life is difficult to define because it differs from one living being to another2 the life of a man is not that of a polyp or of a plant1 and if we find it impossible to discover the line which separates life from the other phenomena of ,nature1 it is in fact because no such line of demarcation exists--the passage from animate to inanimate is gradual and insensible4 ,the step between a stalagmite and a polyp is less than that between a polyp and a man1 and even the trained biologist is often at a loss to determine whether a given borderland form is the result of life1 or of the inanimate forces of the mineral world4 ,a living being is a transformer of matter and energy--both matter and energy being uncreateable and indestructible1 i4e4 invariable in quantity4 ,a living being is only a current of matter and of energy1 both of which change from moment to moment while passing through the organism4 ,that which constitutes a living being is its form2 for a living thing is born1 develops1 and dies with the form and structure of its organism4 ,this ephemeral nature of the living being1 which perishes with the destruction of its form1 is in xiv marked contrast to the perennial character of the matter and the energy which circulate within it4 ,the elementary phenomenon of life is the contact between an alimentary liquid and a cell4 ,for the essential phenomenon of life is nutrition1 and in order to be assimilated all the elements of an organism must be brought into a state of solution4 ,hence the study of life may be best begun by the study of those physico-chemical phenomena which result from the contact of two different liquids4 ,biology is thus but a branch of the physico-chemistry of liquids2 it includes the study of electrolytic and colloidal solutions1 and of the molecular forces brought into play by solution1 osmosis1 diffusion1 cohesion1 and crystallization4 ,in this volume ,i have endeavoured to give as much of the science of energetics as can be treated without the use of mathematical formulae2 the conception of entropy and ,carnot's law of thermodynamics are also discussed4 ,the phenomena of catalysis and of diastatic fermentation have for the first time been brought under the general laws of energetics4 ,this ,i have done by showing that catalysis is only one instance of the general law of the transformation of potential into kinetic energy1 viz4 by the intervention of a foreign exciting and stimulating energy which may be infinitely smaller than the energy it transforms4 ,this conception brings life into line with other catalytic actions1 and shows us a living being as a store of potential energy1 to be set free by an external stimulus which may also excite sensation4 ,in a subsequent chapter ,i have dealt with the rise of ,synthetic ,biology1 whose history and methods ,i have described4 ,it is only of late that the progress of physico-chemical science has enabled us to enter into this field of research1 the final one in the evolution of biological science4 ,the present work contains some of the earliest results of this synthetic biology4 ,we shall see how it is possible by the mere diffusion of liquids to obtain forms which imitate with the greatest accuracy not only the ordinary cellular tissues1 but the more complicated striated structures1 such as muscle and mother-of-pearl4 ,we shall also see how it is xv possible by simple liquid diffusion to reproduce in ordered and regular succession complicated movements like those observed in the karyokinesis of the living cell4 ,the essential character of the living being is its ,form4 ,this is the only characteristic which it retains during the whole of its existence1 with which it is born1 which causes its development1 and disappears with its death4 ,the task of synthetic biology is the recognition of those physico-chemical forces and conditions which can produce forms and structures analogous to those of living beings4 ,this is the subject of the chapter on ,morphogenesis4 ,the last chapter deals with the doctrine of ,evolution4 ,the chain of life is of necessity a continuous one1 from the mineral at one end to the most complicated organism at the other4 ,we cannot allow that it is broken at any point1 or that there is a link missing between animate and inanimate nature4 ,hence the theory of evolution necessarily admits the physico-chemical nature of life and the fact of spontaneous generation4 ,only thus can the evolutionary theory become a rational one1 a stimulating and fertile inspirer of research4 ,we seek for the physico-chemical forces which produce forms and structures analogous to those of living beings1 and phenomena analogous to those of life4 ,we study the alterations in environment which modify these forms1 and we seek in the past history of our planet for those natural phenomena which have brought these physico-chemical forces into play4 ,in this way we may find the road which will1 we hope1 lead some day to the discovery of the origin and the evolution of life upon the earth4 99 99 99 99 99 #a ,,the ,,mechanism ,,of ,,life ,,chapter ,i ,,life ,,and ,,living ,,beings ,primitive man distinguished but two kinds of bodies in nature1 those which were motionless and those which were animated4 ,movement was for him the expression of life4 ,the stream1 the wind1 the waves1 all were alive1 and each was endowed with all the attributes of life--will1 sentiment1 and passion4 ,ancient ,greek mythology is but the poetic expression of this primitive conception4 ,in the evolution of the intelligence1 as in that of the body1 the development of the individual is but a repetition of the development of the race4 ,even now children attribute life to everything that moves4 ,for them a little bird still lives in the inside of a watch1 and produces the tick-tick of the wheels4 ,in modern times1 however1 we have learnt that everything in nature moves1 so that motion of itself cannot be considered as the characteristic of life4 ,heraclitus aptly compares life to a flame4 ,aristotle says1 ,life is nutrition1 growth1 and decay1--having for its cause a principle which has its end in itself1 namely ,greek3 entelecheia4 ,this principle is itself in need of definition1 and ,aristotle only substitutes one unknown epithet for another4 ,bichat defined life as the ensemble of the functions which resist death4 ,this is to define life in terms of death1--but death is but the end of life1 and cannot be defined without first defining life4 ,claude ,bernard rejects all definition of life as insufficient1 and incompatible with experimental science4 #b ,some modern physiologists regard sensibility1 others irritability1 as the characteristic of life1 and define life as the faculty of responding1 by some sort of change1 to an external stimulus4 ,as in the case of movement1 we have found by more attentive observation that this faculty also is universal in nature4 ,there is no action without reaction2 an elastic body repels the body that strikes it4 ,every object in nature dilates with heat1 contracts with cold1 and is modified by the light which it absorbs4 ,everything in nature responds to exterior action by a change1 and hence this faculty cannot be the characteristic of life4 ,a distinguished professor of physiology was accustomed to teach that the disproportion between action and reaction was the characteristic of life4 ,allow a gramme weight to fall on a nerve1 and the muscle will raise a weight of ten grammes4 ,this disproportion is the characteristic of life4 ,but there is a much greater disproportion between action and reaction when the friction of a match blows up a powder factory1 or the turning of a switch lights the lamps and animates the tramways and the motors of a great city4 ,the disproportion between action and reaction is therefore no characteristic of life4 ,the essential characteristic of life is often said to be nutrition--the phenomenon by which a living organism absorbs matter from its environment1 subjects it to chemical metamorphosis1 assimilates it1 and finally ejects the destructive products of metamorphosis into the surrounding medium4 ,but this characteristic is also common to a great number of ordinary chemical reactions1 so that we cannot call it peculiar to life4 ,consider1 for instance1 a fragment of calcium chloride immersed in a solution of sodium carbonate4 ,it absorbs the carbonic ion1 incorporates it into a molecule of calcium carbonate1 and ejects the chlorine ion into the surrounding medium4 ,it may be argued that this is merely a chemical process1 since the substance which determines the reaction is also modified1 the chloride of calcium changing into carbonate of calcium4 ,but every living thing is also changing its chemical #c constitution during every moment of its existence1--it is this change which constitutes the process of senile involution4 ,the substance of the child is other than that of the ovum1 and the substance of the adult is not that of the child4 ,hence we cannot regard nutrition as the exclusive characteristic of life4 ,other authorities regard growth and organization as the essentials of life4 ,but crystals also grow4 ,it was said that the growth of a crystal differed from that of a living thing1 in that the former grew by the addition of material from without--the juxtaposition of bricks1 as it were--while the latter grew by intussusception1 an introduction of fresh material into the substance of the organism4 ,a crystal1 moreover1 was homogeneous1 while the tissues of a living being were differentiated--such differentiation constituting the organization4 ,at the present time1 however1 we recognize the existence of a great variety of purely physical productions1 the so-called osmotic growths1 which increase by a process of intussusception1 and develop therefrom a marvellous complexity of organization and of form4 ,hence growth and organization cannot be considered as the essential characteristics of life4 ,since1 then1 we are totally unable to define the exact boundary which separates life from the physical phenomena of nature1 we may fairly conclude that no such separation exists4 ,this is in conformity with the law of continuity1--the principle which asserts that all the phenomena of nature are continuous in time and space4 ,classes1 divisions1 and separations are all artificial1 made not by nature but by man4 ,all the forms and phenomena of nature are united by insensible transition2 it is impossible to separate them1 and in the distinction between living and non-living things we must content ourselves with relative definitions1 which are far from being precise4 ,life can only be defined as the sum of all phenomena exhibited by living beings1 and its definition thus becomes a mere corollary to the definition of a living being4 ,the true definition of a living being is that it is a transformer of energy1 receiving from its environment the energy #d which it returns to that environment under another form4 ,all living organisms are transformers of energy4 ,a living organism is also a transformer of matter4 ,it absorbs matter from its environment1 transforms it1 and returns it to its environment in a different chemical condition4 ,living things are chemical transformers of matter4 ,living beings are also transformers of form4 ,they commence as a very simple form1 which gradually develops and becomes more complicated4 ,the matter of which a living organism is constituted consists essentially of certain solutions of crystalloids and colloids4 ,to this we may add an osmotic membrane to contain the liquids1 and a solid skeleton to support and protect them4 ,finally1 it would seem that a colloid of one of the albuminoid groups is a necessary constituent of every living being4 ,we may say1 then1 that a living being is a transformer of energy and of matter1 containing certain albuminoid substances1 with an evolutionary form1 the constitution of which is essentially liquid4 ,a living being has but a limited duration4 ,it is born1 develops1 becomes organized1 declines and dies4 ,through all the metamorphoses of form1 of substance1 and of energy1 informing the whole course of its existence1 there is a certain co-ordination1 a certain harmony1 which is necessary for the conservation of the individual4 ,this harmony we call ,life4 ,discord is disease1--the total cessation of the harmony is ,death4 ,when the form is profoundly altered and the substance changed1 the transformation of energy no longer follows its regular course1 the organism is dead4 ,after death the colloids which have constituted the form of the living thing pass from their liquid state as sols into their coagulated state as gels4 ,the metamorphoses of form1 substance1 and energy still continue1 but no longer harmoniously for the conservation of the individual1 but in dis-harmony for its dissolution4 ,finally1 the form of the individual disappears1 the substance and the energy of the living being is resolved and dispersed into other bodies and other phenomena4 #e ,the results hitherto obtained from the study of life seem but inconsiderable when compared with the time and labour devoted to the question4 ,max ,verworn exclaims1 ,are we on a false track8 ,do we ask our questions of ,nature amiss1 or do we not read her answers aright8 ,each branch of science at its commencement employs only the simpler methods of observation4 ,it is purely descriptive4 ,the next step is to separate the different parts of the object studied--to dissect and to analyse4 ,the science has now become analytical4 ,the final stage is to reproduce the substances1 the forms1 and the phenomena which have been the subject of investigation4 ,the science has at last become synthetical4 ,up to the present time1 biology has made use only of the first two methods1 the descriptive and the analytical4 ,the analytical method is at a grave disadvantage in all biological investigations1 since it is impossible to separate and analyse the elementary phenomena of life4 ,the function of an organ ceases when it is isolated from the organism of which it forms a part4 ,this is the chief cause of our lack of progress in the analysis of life4 ,it is only recently that we have been able to apply the synthetic method to the study of the phenomena of life4 ,now that we know that a living organism is but the arena for the transformation of energy1 we may hope to reproduce the elementary phenomena of life1 by calling into play a similar transformation of energy in a suitable medium4 ,organic chemistry has already obtained numerous victories in the same direction1 and the rapid advance in the production of organic bodies by chemical synthesis may be considered the first-fruits of synthetic biology4 ,a phenomenon is determined by a number of circumstances which we call its causes1 and of which it is the result4 ,every phenomenon1 moreover1 contributes to the production of other phenomena which are called its consequences4 ,in order therefore to understand any phenomenon in its entirety1 we must determine all its causes both qualitatively and quantitatively4 ,phenomena succeed one another in time as consequences #f one of another1 and thus form an uninterrupted chain from the infinite of the past into the infinite of the future4 ,a living being gathers from its entourage a supply of matter and of energy1 which it transforms and returns4 ,it is part and parcel of the medium in which it lives1 which acts upon it1 and upon which it acts4 ,the living being and the medium in which it exists are mutually interdependent4 ,this medium is in its turn dependent on its entourage1--and so on from medium to medium throughout the regions of infinite space4 ,one of the great laws of the universe is the law of continuity in time and space4 ,we must not lose sight of this law when we attempt to follow the metamorphoses of matter1 of energy and of form in living beings4 ,evolution is but the expression of this law of continuity1 this succession of phenomena following one another like the links of a chain1 without discontinuity through the vast extent of time and space4 ,the other great universal law1 that of conservation1 applies with equal force to living and to inanimate things4 ,this law asserts the uncreateability and the indestructibility of matter and of energy4 ,a given quantity of matter and of energy remains absolutely invariable through all the transformations through which it may pass4 ,we need not here discuss the question of the possible transformation of matter into ether1 or of ether into ponderable matter4 ,such a transformation1 if it exists1 would have but little bearing on the phenomena of life4 ,moreover1 it also will probably be found to conform to the law of conservation of energy4 ,in marked contrast to the permanence of matter and of energy is the ephemeral nature of form1 as exhibited by living beings4 ,function1 since it is but the resultant of form1 is also ephemeral4 ,all the faculties of life are bound up with its form1--a living being is born1 exists1 and dies with its form4 ,the phenomena of life may in certain cases slow down from their normal rapidity and intensity1 as in hibernating #g animals1 or be entirely suspended1 as in seeds4 ,this state of suspension of life1 of latent life as it were1 reminds us of a machine that has been stopped1 but which retains its form and substance unaltered1 and may be started again whenever the obstacle to its progress is removed4 ,during the whole course of its life a living being is intimately dependent on its entourage4 ,for example1 the phenomena of life are circumscribed within very narrow limits of temperature4 ,a living organism1 consisting as it does essentially of liquid solutions1 can only exist at temperatures at which such solutions remain liquid1 i4e4 between #j;deg ,c4 and #ajj;deg ,c4 ,certain organisms1 it is true1 may be frozen1 but their life remains in a state of suspension so long as their substance remains solid4 ,since the albuminoid substances which are a necessary component of the living organism become coagulated at #dd;deg ,c41 the manifestations of life diminish rapidly above this temperature4 ,the intensity of life may be said to augment gradually as the temperature rises from #j;deg to #dj;deg1 and then to diminish rapidly as the temperature rises above that point1 becoming nearly extinct at #fj;deg ,c4 ,another condition indispensable to life is the presence of oxygen4 ,life1 compared by ,heraclitus to a flame1 is a combustion1 an oxydation1 for which the presence of oxygen at a certain pressure is indispensable4 ,there are1 it is true1 certain anaerobic micro-organisms which apparently exist without oxygen1 but these in reality obtain their oxygen from the medium in which they grow4 ,life is also influenced by light1 by mechanical pressure1 by the chemical composition of its entourage1 and by other conditions which we do not as yet understand4 ,in each case the conditions which are favourable or noxious vary with the nature of the organism1 some living in air1 some in fresh water1 and others in the sea4 ,formerly it was supposed that the substance of a living being was essentially different from that of the mineral world1 so much so that two distinct chemistries were in existence--organic chemistry1 the study of substances derived from bodies which had once possessed life1 and inorganic chemistry1 dealing #h with minerals1 metalloids1 and metals4 ,we now know that a living organism is composed of exactly the same elements as those which constitute the mineral world4 ,these are carbon1 oxygen1 hydrogen1 nitrogen1 phosphorus1 calcium1 iron1 sulphur1 chlorine1 sodium1 potassium1 and one or two other elements in smaller quantity4 ,it was formerly supposed that the organic combinations of these elements were found only in living organisms and could be fashioned only by vital forces4 ,in more recent times1 however1 an ever increasing number of organic substances have been produced in the laboratory4 ,organic bodies may be divided into four principal groups4 7#a7 ,carbohydrates1 including the sugars and the starches1 all of which may be considered as formed of carbon and water4 7#b7 ,fats1 which may be considered chemically as the ethers of glycerine1 combinations of one molecule of glycerine and three molecules of a fatty acid1 with elimination of water4 7#c7 ,albuminoids1 substances whose molecules are complex1 containing nitrogen and sulphur in addition to carbon1 oxygen1 and hydrogen4 ,the albuminoid of the cell nucleus also contains phosphorus1 and the haemoglobin of the blood contains iron4 7#d7 ,minerals or inorganic elements1 such as chloride of sodium1 phosphate of calcium1 and carbonic acid4 ,this group also includes water1 which is the most important constituent1 since it forms more than a moiety of the substance of all living creatures4 ,woehler in #ahbh accomplished the first synthesis of an organic substance1 urea1 one of the products of the decomposition of albumin4 ,since then a large number of organic substances have been prepared by the synthesis of their inorganic elements4 ,the most recent advance in this direction is that of ,emile ,fischer1 who has produced polypeptides having the same reactions as the peptones1 by combining a number of molecules of the amides of the fatty acids4 ,in the further synthesis of organic compounds the problems we have before us are of the same order as those already solved4 ,there is no essential difference between organic and inorganic chemistry2 living organisms are formed of the #i same elements as the mineral world1 and the organic combinations of these elements may be realized in our laboratories1 just as in the laboratory of the living organism4 ,not only so1 but a living being only borrows for a short time those mineral elements which1 after having passed through the living organism1 are returned once again to the mineral kingdom from which they came4 ,all matter has life in itself--or1 at any rate1 all matter susceptible of incorporation in a living cell4 ,this life is potential while the element is in the mineral state1 and actual while the element is passing through a living organism4 ,mineral matter is changed into organic matter in its passage through a vegetable organism4 ,the carbonic acid produced by combustion and respiration is absorbed by the chlorophyll of the leaves under the stimulus of light--the oxygen of the carbonic acid being returned to the air1 while the carbon is utilized by the plant for the formation of sugar1 starch1 cellulose1 and fats4 ,thus plants are fed in great part by their leaves1 taking an important part of their nourishment from the air1 while by their roots they draw from the earth the water1 the phosphates1 the mineral salts1 and the nitrates required for the formation of their albuminoid constituents4 ,a vegetable is a laboratory in which is carried out the process of organic synthesis by which mineral materials are changed into organic matter4 ,the first synthetic reaction is the formation of a molecule of formic aldehyde1 ,,ch#b,o1 by the combination of a molecule of water with an atom of carbon4 ,from this formic aldehyde1 or formol1 we may obtain all the various carbohydrates by simple polymerization1 i4e4 by the association of several molecules1 with or without elimination of water4 ,thus two molecules of formol form one molecule of acetic acid1 #b;,,ch#b,o ,c#b;,h#d,o#b4 ,three molecules of formol form a molecule of lactic acid1 #c;,,ch#b,o ,c#c;,h#f,o#c4 ,six molecules of formol represent glucose and levulose1 #f;,,ch#b,o ,c#f;,h#ab,o#f4 ,twelve molecules of formol minus one molecule of water form saccharose1 lactose1 cane sugar1 and sugar of milk1 #ab;,,ch#b,o ,c#ab;,h#bb,o#aa ,h#b,o2 n times six #aj molecules of formol minus one molecule of water1 n7,c#f;,h#aj,o#e71 form starch and cellulose4 ,animals derive their nourishment from vegetables either directly1 or indirectly through the flesh of herbivorous animals4 ,the mineral matter1 rendered organic in its passage through a vegetable growth1 is finally returned by the agency of animal organisms to the mineral world again1 in the form of carbonic acid1 water1 urea1 and nitrates4 ,thus vegetables may be regarded as synthetic agents1 and animals and microbes as agents of decomposition4 ,here also the difference is only relative1 for in certain cases vegetables produce carbonic acid1 while some animal organisms effect synthetic combinations4 ,moreover1 there are intermediary forms1 such as fungi1 which possessing no chlorophyll are nourished like animals by organic matter1 and yet like vegetables are able to manufacture organic matter from mineral salts4 ,the work of combustion begun by the animal organism is finished by the action of micro-organisms1 who complete the oxydation--the re-mineralization of the chemical substances drawn originally from the inorganic world by the agency of plant life4 ,to sum up4 ,vegetables obtain their nourishment from mineral substances1 which they reduce1 de-oxydize1 and charge with solar energy4 ,animal organisms on the contrary oxydize1 and micro-organisms complete the oxydation of these substances1 returning them to the mineral world as water1 carbonates1 nitrates1 and sulphates4 ,thus matter circulates eternally from the mineral to the vegetable1 from the vegetable to the animal world1 and back again4 ,the matter which forms our structure1 which is to-day part and parcel of ourselves1 has formed the structure of an infinite number of living beings1 and will continue to pursue its endless reincarnation after our decease4 ,this endless cycle of life is also an endless cycle of energy4 ,the combination of carbon with water carried out by the agency of chlorophyll can only take place with absorption of energy4 ,this energy comes directly from the sun1 the red and orange light radiations being absorbed by the chlorophyll4 #aa ,the arrest of vegetation during the winter months is due not so much to the lowering of temperature as to the diminution of the radiant energy received from the sun4 ,in the same way shade is harmful to vegetation1 since the radiant energy required for growth is prevented from reaching the plant4 ,the energy radiated by the sun is accumulated and stored in the plant tissues4 ,later on1 animals feed on the plants and utilize this energy1 excreting the products of decomposition1 i4e4 the constituents of their food minus the energy contained in it4 ,thus the whole of the energy which animates living beings1 the whole of the energy which constitutes life1 comes from the sun4 ,to the sun also we owe all artificial heat1 the energy stored up in wood and coal4 ,we are all of us children of the sun4 ,the radiant energy of the sun is transformed by plants into chemical energy4 ,it is this chemical energy which feeds the vital activity of animals1 who return it to the external world under the form of heat1 mechanical work1 and muscular contraction1 light in the glow-worm1 electricity in the electric eel4 ,there is a marked difference between the forms affected by organic and inorganic substances4 ,the forms of the mineral world are those of crystals--geometrical forms1 bounded by straight lines1 planes1 and regular angles4 ,living organisms1 on the contrary1 affect forms which are less regular--curved surfaces and rounded angles4 ,the physical reason for this difference in form lies in a difference of consistency1 crystals being solid1 whereas living organisms are liquids or semi-liquids4 ,the liquids of nature1 streams and clouds and dewdrops1 affect the same rounded forms as those of living organisms4 ,living beings for the most part present a remarkable degree of symmetry4 ,some1 like radiolarians and star-fish1 have a stellate form4 ,in plants the various organs often radiate from an axis1 in such a manner that on turning the plant about this axis the various forms are superposed thrice1 four1 or more often five times in one complete revolution4 ,it is remarkable how often this number five recurs in the #ab divisions and parts of a living organism4 ,in other cases the similar parts are disposed symmetrically on either side of a median line or plane1 giving a series of homologous parts which are not superposable4 ,the most important characteristic of a living being is its form4 ,this is implicitly admitted by naturalists1 who classify animals and plants in genera and species according to the differences and analogies of their form4 ,all living beings are composed of elementary organizations called cells4 ,in its complete state1 a cell consists of a membrane or envelope containing a mass of protoplasm1 in the centre of which is a nucleus of differentiated protoplasm4 ,this nucleus may in its turn contain a nucleolus4 ,in some cases the cell is merely a protoplasmic mass without a visible envelope1 so that a cell may be defined as essentially a mass of protoplasm provided with a nucleus4 ,a living organism may consist merely of a single cell1 which is able alone to accomplish all the functions of life4 ,most living beings1 however1 consist of a collection of innumerable cells forming a cellular association or community4 ,when a number of cells are thus united to constitute a single living being1 the various functions of life are divided among different cellular groups4 ,certain cells become specialized for the accomplishment of a single function1 and to each function corresponds a different form of cell4 ,it is thus easy to recognize by their form the nerve cells1 the muscle cells which perform the function of movement1 and the glandular cells which perform the function of secretion4 ,the cells of a living being are microscopic in size1 and it is remarkable that they never attain to any considerable dimensions4 ,in order that life may be maintained in a living organism1 it is necessary that a continual supply of aliment should be brought to it1 and that certain other substances1 the waste-products of combustion1 should be eliminated4 ,in order to be absorbed and assimilated1 the alimentary substances must be presented to the living organism in a liquid or gaseous state4 ,thus the essential condition necessary for the #ac maintenance of life is the contact of a living cell with a current of liquid4 ,the elementary physical phenomenon of life is the contact of two different liquids4 ,this is the necessary condition which renders possible the chemical exchanges and the transformations of energy which constitute life4 ,it is in the study of the phenomena of liquid contact and diffusion that we may best hope to pierce the secrets of life4 ,the physics of vital action are the physics of the phenomena which occur in liquids1 and the study of the physics of a liquid must be the preface and the basis of all inquiry into the nature and origin of life4 99 99 99 99 99 #ad ,,chapter ,,ii ,,solutions ,we have seen that living beings are transformers of energy and of matter1 evolutionary in form and liquid in consistency2 that they are solutions of colloids and crystalloids separated by osmotic membranes to form microscopic cells1 or consisting merely of a gelatinous mass of protoplasm1 with a nucleus of slightly differentiated material4 ,the elementary phenomenon of life is the contact of two different solutions4 ,this is the initial physical phenomenon from which proceed all the other phenomena of life in accordance with the ordinary chemical and physical laws4 ,thus the basis of biological science is the study of solution and of the phenomena which occur between two different solutions1 either in immediate contact or when separated by a membrane4 ,a solution is a homogeneous mixture of one or more solutes in a liquid solvent4 ,before solution the solute or dissolved substance may be solid1 liquid1 or gaseous4 ,solutes1 or substances capable of solution1 may be divided into two classes--substances which are capable of crystallization1 or crystalloids2 and those which are incapable of crystallization1 the colloids4 ,crystalloids may be divided again into two classes1 those whose solutions are ionizable and therefore conduct electricity1 chiefly salts1 acids1 and bases2 and those whose solutions are non-ionizable and are therefore non-conductors4 ,these latter are for the most part crystallizable substances of organic origin1 such as sugars1 urea1 etc4 ,avogadro's law asserts that under similar conditions of temperature and pressure1 equal volumes of various gases #ae contain an equal number of molecules4 ,under similar conditions1 the molecular weights of different substances have therefore the same ratio as the weights of equal volumes of their vapours4 ,hence if we fix arbitrarily the molecular weight of any one substance1 the molecular weight of all other substances is thereby determined4 ,the molecular weight of hydrogen has been arbitrarily fixed as two1 and hence the molecular weight of any substance will be double its gaseous density when compared with that of hydrogen4 ,gramme-,molecule4--,a gramme-molecule is the molecular weight of a body expressed in grammes4 ,occasionally for brevity a gramme-molecule is spoken of as a molecule4 ,thus we may say that the molecular weight of oxygen is #af grammes1 meaning thereby that there are the same number of molecules in #af grammes of oxygen as there are atoms in #a gramme of hydrogen4 ,concentration4--,the concentration of a solution is the ratio between the quantity of the solute and the quantity of the solvent4 ,the concentration of a solution is expressed in various ways4 7a7 ,the weight of solute dissolved in #ajj grammes of the solvent4 7b7 ,the weight of solute present in #ajj grammes of the solution4 7c7 ,the weight of solute dissolved in a litre of the solvent4 7d7 ,the weight of solute in a litre of the solution4 ,the most usual method is to give the concentration as the weight of solute dissolved in #ajj grammes or in one litre of the solvent4 ,molecular ,concentration4--,many of the physical and biological properties of a solution are proportional1 not to its mass or weight concentration1 but to its molecular concentration1 i4e4 to the number of gramme-molecules of the solute contained in a litre of the solution4 ,many physical properties are quite independent of the nature of the solute1 depending only on its degree of molecular concentration4 ,normal ,solution4--,a normal solution is one which contains one gramme-molecule of the solute per litre4 ,a decinormal solution contains one-tenth of a gramme-molecule of the solute per litre1 and a centinormal solution one-hundredth of a gramme-molecule4 ,a normal solution of urea1 for example1 #af contains #fj grammes of urea per litre1 while a normal solution of sugar contains #cdb grammes of sugar per litre4 ,the ,dissolved ,substance is a ,gas4--,van t' ,hoff1 using the data obtained by the botanist ,pfeffer1 showed that the dissolved matter in a solution behaved exactly as if it were a gas4 ,the analogy is complete in every respect4 ,like the gaseous molecules1 the molecules of a solute are mobile with respect to one another4 ,like those of a gas1 the molecules of a solute tend to spread themselves equally1 and to fill the whole space at their disposal1 i4e4 the whole volume of the solution4 ,the surface of the solution represents the vessel containing the gas1 which confines it within definite limits and prevents further expansion4 ,osmotic ,pressure4--,like the molecules of a gas1 the molecules of a solute exercise pressure on the boundaries of the space containing it4 ,this osmotic pressure follows exactly the same laws as gaseous pressure4 ,it has the same constants1 and all the notions acquired by the study of gaseous pressure are applicable to osmotic pressure4 ,osmotic pressure is in fact the gaseous pressure of the molecules of the solute4 ,when a gas dilates and increases in volume1 its temperature falls1 and cold is produced4 ,similarly1 when a soluble substance is dissolved1 it increases in volume1 and the temperature of the liquid falls4 ,this phenomenon is well known as a means of producing cold by a refrigerating mixture4 ,the phenomena of life are governed by the laws of gaseous pressure1 since all these phenomena take place in solutions4 ,the fundamental laws of biology are those of the distribution of substances in solution1 which is regulated by the laws of gaseous pressure1 since all these laws are applicable also to osmotic pressure4 ,boyle's ,law4--,when a gas is compressed its volume is diminished4 ,if the pressure is doubled1 the volume is reduced to one-half4 ,the quantity ,v x ,p1 that is the volume multiplied by the pressure1 is constant4 ,gay-,lussac's ,law4--,for a difference of temperature of a degree ,centigrade all gases dilate or contract by #a _/ #bgc of their volume at #j;deg ,centigrade4 #ag ,dalton's ,law4--,in a gaseous mixture1 the total pressure is equal to the sum of the pressures which each gas would exert if it alone filled the whole of the receptacle4 ,pressure proportional to ,molecular ,concentration4--,the above laws are completely independent of the chemical nature of the gas1 they depend only on the number of gaseous molecules in a given space1 i4e4 on the molecular concentration4 ,if we double the mass of the gas in a given space1 we double the number of molecules1 and we also double the pressure1 whatever the nature of the molecules4 ,we may also double the pressure by compressing the molecules of a gas1 or of several gases1 into a space half the original size4 ,the molecular concentration of a gas1 or of a mixture of gases1 is the ratio of the number of molecules to the volume they occupy4 ,the pressure of a gas or of a mixture of gases is proportional to its molecular concentration4 ,this is a better and a shorter way of expressing both ,boyle's law and ,dalton's law4 ,one gramme-molecule of a gas1 whatever its nature1 condensed into the volume of #a litre1 has a pressure of #bb4ce atmospheres4 ,similarly one gramme-molecule of a solute1 whatever its nature1 when dissolved in a litre of water1 has the same pressure1 viz4 #bb4ce atmospheres4 ,absolute ,zero4--,according to ,gay-,lussac's law1 the volume of a gas diminishes by #a _/ #bgc of its volume at #j;deg ,c4 for each degree fall of temperature4 ,thus if the contraction is the same for all temperatures1 the volume would be reduced to zero at -#bgc;deg ,c4 ,this is the absolute zero of temperature4 ,temperatures measured from this point are called absolute temperatures1 and are designated by the symbol ,t4 ,if tdeg indicates the ,centigrade temperature above the freezing point of water1 then the absolute temperature is equal to tdeg #bgc;deg4 ,the ,gaseous ,constant4--,consider a mass of gas at #j;deg ,c4 under a pressure ,po1 with volume ,vo4 ,at the absolute temperature ,t1 if the pressure be unaltered1 the volume of this gas will be ,vo,t _/ #bgc4 ,therefore the constant ,,pv1 the product of the pressure by the volume1 will be represented by ,po,vo,t _/ #bgc4 #ah ,at the same temperature1 but under another pressure ,p' the gas will have a different volume ,v'4 ,since1 according to ,boyle's law1 ,,pv is constant 7,p',v' ,po,vo71 it will still equal ,po,vo,t _/ #bgc4 ,therefore ,po,vo _/ #bgc is also constant4 ,this quantity is called the gaseous constant1 and if we represent it by the symbol ,r1 we obtain the general formula ,,pv ,,rt for all gases1 or ,,pv _/ ,t ,r4 ,suppose1 for instance1 we have a gramme-molecule of a gas at #j;deg ,c4 in a space of #a litre4 ,it has a pressure of #bb4ce atmospheres at #j;deg ,c41 or #bgc;deg absolute temperature4 ,since ,,pv ,,rt1 ,r ,,pv _/ ,t #a x #bb4ce _/ #bgc 4#jhai4 ,this number 4#jhai is the numerical value of the constant ,r for all gases1 volume being measured in litres and pressure in atmospheres4 ,substances in solution behave exactly like gases1 they follow the same laws and have the same constants4 ,all the conceptions which have been acquired by the study of gases are applicable to solutions1 and therefore to the phenomena of life4 ,the osmotic pressure of a solution is the force with which the molecules of the solute1 like gaseous molecules1 strive to diffuse into space1 and press on the limits which confine them1 the containing vessel being represented by the surfaces of the solution4 ,osmotic pressure is measured in exactly the same way as gaseous pressure4 ,to measure steam pressure we insert a manometer in the walls of the boiler4 ,in the same way we may use a manometer to measure osmotic pressure4 ,we attach the tube to the walls of the porous vessel1 allow the solvent to increase in volume under the pressure of the solute1 and measure the rise of the liquid in the manometer tube4 ,pfeffer's ,apparatus4--,pfeffer has designed an apparatus for the measurement of osmotic pressure4 ,it consists of a vessel of porous porcelain1 the pores of which are filled with a colloidal solution of ferrocyanide of copper4 ,this forms a semi-permeable membrane which permits the passage of water into the vessel1 but prevents the passage of sugar or of any #ai colloid4 ,the stopper which hermetically closes the vessel is pierced for the reception of a mercury manometer4 ,the vessel is filled with a solution of sugar and plunged in a bath of water4 ,the volume of the solution in the interior of the vessel can vary1 since water passes easily in either direction through the pores of the vessel4 ,the boundary of the solvent has become extensible1 and its volume can increase or diminish in accordance with the osmotic pressure of the solute4 ,under the pressure of the sugar water is sucked into the vessel like air into a bellows1 the solution passes into the tube of the manometer1 and raises the column of mercury until its pressure balances the osmotic pressure of the sugar molecules4 ,osmotic ,pressure follows the ,laws of ,gaseous ,pressure4--,this osmotic pressure is in fact gaseous pressure1 and may be measured in millimetres of mercury in just the same way4 ,we may thus show that osmotic pressure follows the laws of gaseous pressure as defined by ,boyle1 ,dalton1 and ,gay-,lussac4 ,the coefficient of pressure variation for change of temperature is the same for a solute as for a gas4 ,the formula ,,pv ,,rt is applicable to both4 ,the numerical value of the constant ,r is also the same for a solute as for a gas4 being 4#jhai for one gramme-molecule of either1 when the volume is expressed in litres and the pressure in atmospheres4 ,the formula ,,pv ,,rt shows that for a given mass1 with the same volume1 the pressure increases in proportion to the absolute temperature4 ,osmotic ,pressure of ,sugar4--,a normal solution of sugar1 containing #cdb grammes of sugar per litre1 has a pressure of #bb4ce atmospheres1 and it may well be asked why such an enormous pressure is not more evident4 ,the reason will be found in the immense frictional resistance to diffusion4 ,frictional resistance is proportional to the area of the surfaces in contact1 and this area increases rapidly with each division of the substance4 ,when a solute is resolved into its component molecules1 its surface is enormously increased1 and therefore the friction between the molecules of the solute and those of the solvent4 ,isotonic ,solutions4--,two solutions which have the same #bj osmotic pressure are said to be iso-osmotic or isotonic4 ,when comparing two solutions of different concentration1 the solution with the higher osmotic pressure is said to be hypertonic1 and that with the lower osmotic pressure hypotonic4 ,lowering of the ,freezing ,point4--,pure water freezes at #j;deg ,c4 ,raoult showed that the introduction of a non-ionizable substance1 such as sugar or alcohol1 lowers the freezing point of a solution in proportion to the molecular concentration of the solute4 ,one gramme-molecule of the solute introduced into one litre of the solution lowers its temperature of congelation by #a4he;deg ,c4 ,thus a normal solution of any non-ionizable substance in water freezes at -#a4he;deg ,c4 ,the measurement of this lowering of the freezing point is called ,cryoscopy1 a method which is becoming of great utility in medicine4 ,cryoscopy of ,blood4--,in order to determine the osmotic pressure of the blood at #cg;deg ,c41 i4e4 #ih4f;deg ,f41 the normal temperature1 we proceed as follows4 ,on freezing the blood1 we find that it congeals at -4#ef;deg4 ,its molecular concentration is therefore 4#ef _/ #a4he 4#cj1 or about one-third of a gramme-molecule per litre4 ,its osmotic pressure at #j;deg ,c4 is therefore 4#c x #bb4ce #f4g atmospheres4 ,the increase of pressure with temperature is the same as for a gas1 viz4 #a_/bgc1 or 4#jjcfg of its pressure at #j;deg for every degree rise of temperature4 ,the increase of pressure at #cg;deg is therefore 4#jjcfg x #cg x #f4g 4#i atmospheres4 ,the total osmotic pressure at #cg;deg is therefore #f4g 4#i #g4f atmospheres4 ,rise of ,boiling ,point4--,water under atmospheric pressure boils at a temperature of #ajj;deg ,c4 ,the addition of a solute whose solution does not conduct electricity1 such as sugar1 causes a rise in the boiling point proportional to the molecular concentration of that solute4 ,lowering of the ,vapour ,tension4--,the vapour tension of a liquid is lowered by the addition of a solute4 ,a liquid boils at the temperature at which its vapour tension equals that of the atmosphere4 ,since an aqueous solution of sugar at atmospheric pressure does not begin to boil at #ajj;deg ,c41 it is manifest that its vapour tension is then less than that of the #ba atmosphere4 ,the addition of a solute such as sugar1 whose solution is not ionizable1 and therefore does not conduct electricity1 lowers the vapour tension of the solution in proportion to the molecular concentration of the solute4 ,corresponding ,values4--,we have thus found five properties of a solution which vary proportionally1 so that from the measurement of any one of them we can determine the corresponding values of all the others4 ,these are-- #a4 ,the ,molecular ,concentration4 #b4 ,the ,osmotic ,pressure4 #c4 ,the ,diminution of ,vapour ,tension4 #d4 ,the ,raising of the ,boiling ,point4 #e4 ,the ,lowering of the ,freezing ,point4 ,cryoscopy4--,the usual method employed for the determination of the molecular concentration and osmotic pressure of a solution is by cryoscopy--the measurement of its temperature of congelation4 ,a very sensitive thermometer is used1 the scale of which extends over only #e;deg and is divided into hundredths of a degree4 ,the liquid under examination is placed in a test tube1 in which the bulb of the thermometer is plunged1 and this is supported in a second tube with an air space all round it4 ,the whole is then suspended to the under side of the cover of the refrigerating vessel1 which may be cooled either by filling it with a freezing mixture1 or by the evaporation of ether4 ,during the whole of the operation the liquid is agitated by a mechanical stirrer4 ,the first step is to determine the freezing point of distilled water4 ,as the water cools the mercury gradually descends in the stem of the thermometer till it reaches a point below the zero mark at #j;deg ,c4 ,as soon as ice begins to form the mercury rises1 at first rapidly and then more slowly1 reaches a maximum1 and finally descends again4 ,this maximum reading is the true point of congelation4 ,the inner tube is then emptied1 care being taken to leave a few small ice crystals to serve as centres of congelation for the subsequent experiment1 thus avoiding supercooling of the solution4 ,the process is then repeated with the solution under examination4 ,the difference between #bb the two freezing points is the required lowering of the freezing point4 ,cryoscopy is the method most used in biological research to determine molecular concentration4 ,it has1 however1 some grave defects4 ,it necessitates several cubic centimetres of the liquid under examination4 ,it gives us the constants of the solution at the temperature of freezing1 which is far below that of life4 ,organic liquids are easily altered and are extremely sensible to minute differences of temperature1 cryoscopy therefore gives us no information as to the constitution of solutions under normal conditions4 ,it is desirable to have some other method of determining molecular concentration and the other interdependent constants at the normal temperature of life4 ,a much better method1 were it possible1 would be the direct determination of the vapour tension of the solutions under normal conditions of temperature and pressure4 ,molecular ,lowering of the ,freezing ,point4--,for every substance whose solution is not ionized and therefore does not conduct electricity1 the lowering of the freezing point is the same1 viz4 #a4he;deg ,c4 for each gramme-molecule of the solute per litre of the solution4 ,determination of the ,molecular ,concentration4--,in order to obtain the molecular concentration of a non-ionizable substance1 we have only to determine the lowering of the freezing point4 ,let ,a be the lowering of the freezing point of any solution4 ,on dividing it by #a4he 7the lowering of the freezing point for a normal solution71 we obtain the number of gramme-molecules in a litre of the solution4 ,if n be the number of gramme-molecules per litre1 then n ,a _/ #a4he4 ,determination of the ,osmotic ,pressure4--,the osmotic pressure ,p of a solution may be obtained by multiplying its molecular concentration n by #bb4ce atmospheres4 ,p n x #bb4ce ,a _/ #a4he x #bb4ce4 ,determination of ,molecular ,weight4--,the lowering of the freezing point also enables us to calculate the molecular #bc weight of any non-ionizable solute4 ,thus ,bouchard has been able to determine by means of cryoscopy the mean molecular weight of the substances eliminated by the urine4 ,a weight x of the substance is dissolved in a litre of water1 and the lowering of the freezing point is observed4 ,the value thus found divided by #a4he gives us n1 the number of gramme-molecules per litre4 ,the molecular weight ,m may be determined by dividing the original weight x by n4 ,the study of osmotic pressure was begun by the ,abbe ,nollet2 and one of his disciples1 ,parrot1 at an early date thus described its importance3 ,it is a force analogous in all respects to the mechanical forces1 a force able to set matter in motion1 or to act as a static force in producing pressure4 ,it is this force which causes the circulation of heterogeneous matter in the liquids which serve as its vehicle4 ,it is this force which produces those actions which escape our notice by their minuteness and bewilder us by their results4 ,it is for the infinitely small particles of matter what gravitation is for heavy masses4 ,it can displace matter in solution upwards against gravity as easily as downwards or in a horizontal direction4 ,thus the recognition of the fact that a substance in solution is really a gas1 has at a single stroke put us in possession of the laws of osmotic pressure--laws slowly and laboriously discovered by the long series of investigations on the pressure of gases4 ,osmotic pressure plays a most important role in the arena of life4 ,it is found at work in all the phenomena of life4 ,when osmotic pressure fails1 life itself ceases4 99 99 99 99 99 #bd ,,chapter ,,iii ,,electrolytic ,,solutions ,solutions which conduct ,electricity4--,the laws of solution which we have studied in the previous chapter apply only to those solutions1 chiefly of organic origin1 which do not conduct electricity4 ,solutions of electrolytes such as the ordinary salts1 acids1 and bases1 which are ionized on solution1 give values for the various constants of solution which do not accord with those required by theory4 ,if1 for instance1 we take a gramme-molecule of an electrolyte such as chloride of sodium1 and dissolve it in a litre of water1 we find that the lowering of the freezing point is nearly double the theoretical value of #a4he;deg4 ,the same holds good for the osmotic pressure1 and for all the constants which are proportional to the molecular concentration of the solute4 ,the solution behaves1 in each case1 as if it contained more than one gramme-molecule of sodium chloride per litre4 ,it behaves1 in fact1 as if it contained i times the number of molecules of solute originally introduced into it4 ,if n be the original number of molecules1 then it will apparently contain n' in molecules4 ,this law is universal for all electrolytic solutions2 the theoretical value for their concentration1 osmotic pressure1 and all the proportional physical constants must be multiplied by this quantity1 i n'_/n1 which is the ratio of the apparent number of the molecules present to the number originally introduced4 ,a similar dissociation of the molecule is observed in the case of many gases4 ,the vapour of chloride of ammonium1 for instance1 is decomposed by heat1 and it may be shown experimentally that the increase of pressure on heating above #be that which theory demands1 is due to an increase in the number of the gaseous molecules present4 ,some of the vapour particles are dissociated into two or more fragments1 each of which plays the part of a single molecule4 ,arrhenius1 in #ahhe1 advanced the hypothesis that the apparent increase in the number of molecules of an electrolytic solution was also due to dissociation4 ,this interpretation at once threw a flood of light on a number of phenomena hitherto obscure4 ,coefficient of ,dissociation4--,we have seen that in order to obtain values which accord with experiment we have to multiply the number of gramme-molecules of the solute by the coefficient i1 which is called the ,coefficient of ,dissociation4 ,this coefficient of dissociation1 i1 may be found by observing the lowering of the freezing point of a normal solution1 and dividing it by #a4he4 i t_/#a4he4 ,the coefficient of dissociation varies with the degree of concentration of the solution1 rising to a maximum when the solution is sufficiently diluted4 ,if we know i1 the coefficient of dissociation for a given solute1 contained in a solution of a definite concentration1 we can find n'1 the number of particles present in a solution containing n gramme-molecules of the solute per litre1 since n' in4 ,on the other hand1 if from a consideration of its freezing point and other constants we find that an electrolytic solution appears to contain n' gramme-molecules per litre1 the real number of chemical gramme-molecules in one litre of the solution will be only n' _/ i n4 ,very concentrated solutions do not conform to these laws4 ,in this they resemble gases1 which as they approach their point of condensation tend less and less to conform to the laws of gaseous pressure4 ,electrolysis4--,if we take a solution of an acid1 a salt1 or a base1 and dip into it two metallic rods1 one connected to the positive and the other to the negative pole of a battery1 we #bf find that the metals or metallic radicals of the solution are liberated at the negative pole1 while the acid radicals of the salts and acids and the hydroxyl of the bases are liberated at the positive pole4 ,the liberated substances may either be discharged unchanged1 or they may enter into new combinations1 causing a series of secondary reactions4 ,electrolytes4--,solutions which conduct electricity are called ,electrolytes1 and the conducting metallic rods dipping into the solution are the ,electrodes4 ,faraday gave the names of ,ions to the atoms or atom-groups liberated at either electrode4 ,the ions liberated at the positive electrode are the ,anions1 and those at the negative electrode are the ,cations4 ,the only solutions which possess any notable degree of electrical conductivity are the aqueous solutions of the various salts1 acids1 and bases1 and in these solutions only do we meet with those phenomena of dissociation which are evidenced by anomalies of osmotic pressure1 freezing point and the like1--anomalies which show that the solution contains a greater number of molecules than that indicated by its molecular concentration4 ,these anomalies are due to dissociation1 the division of some of the molecules into fragments1 each of which plays the part of a separate molecule1 contributing its quota to the osmotic tension and vapour pressure of the solution1 in fact to all the phenomena which are dependent on the degree of molecular concentration4 ,the electrical conductivity of a solution is therefore proved to be dependent on its molecular dissociation4 ,arrhenius' ,theory of ,electrolysis4--,in #ahhe1 ,arrhenius brought forward his theory of the transport of electricity by an electrolyte4 ,according to this hypothesis1 the electric current is carried by the ions1 the positive charges by the cations1 and the negative charges by the anions4 ,in virtue of the attraction between charges of different sign1 and repulsion between charges of like sign1 the cations are repelled by the positive charge on the anode1 and attracted by the negative charge on the cathode4 ,similarly the anions are repelled by the cathode and attracted by the anode4 #bg ,an electrolytic solution contains three varieties of particles1 positive ions or cations1 negative ions or anions1 and undissociated neutral molecules4 ,the molecular concentration of such a solution1 with the corresponding constants1 depends on the total number of these particles1 i4e4 the sum of the ions and the undissociated neutral molecules4 ,we may indicate an ion by placing above it the sign of its electrical charge1 one sign for each valency4 ,thus ,na and ,cl- indicate the two ions of a salt solution2 ,cu and ,,so#d-- the two ions of a solution of sulphate of copper4 ,a point is sometimes substituted for the sign1 and a comma for the - sign4 ,thus ,na4 and ,cl12 ,cu44 and ,,so#d114 ,my friend ,dr4 ,lewis ,jones has given a very vivid picture of the processes which go on in an electrolytic solution when an electric current is passing4 ,he compares an electrolytic cell to a ballroom1 in which are gyrating a number of dancing couples1 representing the neutral molecules1 and a number of isolated ladies and gentlemen representing the anions and cations respectively4 ,if we suppose a mirror at one end of the ballroom and a buffet at the other1 the ladies will gradually accumulate around the mirror1 and the gentlemen around the buffet4 ,moreover1 the dancing couples will gradually be dissociated in order to follow this movement4 ,degree of ,dissociation4--,the degree of dissociation is the fraction of the molecules in the solution which have undergone dissociation4 ,let n be the total number of molecules of the solute1 and n the number of dissociated molecules4 ,then n _/ n a will represent the degree of dissociation4 ,let k be the number of ions into which each molecule is split4 ,then a nk _/ nk1 i4e4 the degree of dissociation is the ratio of the number of ions actually present in a solution to the number which would be present if all the molecules of the solute were dissociated4 ,let n' be the total number of particles present in a solution #bh containing n molecules1 each of which is composed of k ions4 ,then if a is the degree of dissociation1 n' n - an ank1 n' n#a a 7k - #a71 n' _/ n #a a 7k - #a7 i4 ,we thus obtain i the coefficient of dissociation1 in terms of the degree of dissociation a and the number of ions in each molecule k4 ,if there is no dissociation1 i4e4 if a #j1 then n' n1 and i #a4 ,if all the molecules are dissociated1 a #a1 and i k4 ,faraday's ,law4--,faraday found that the quantity of electricity required to liberate one gramme-molecule of any radical is #if4ecg coulombs for each valency of the radical4 ,electrochemical ,equivalent4--,the electrochemical equivalent of a radical is the weight liberated by one coulomb of electricity4 ,it is equal to the molecular weight of the ion1 divided by #if4ecg times its valency4 ,electrolytic ,conductivity4--,the conductivity of an electrolyte is the inverse of its resistance4 ,c #a_/,r4 ,for a given difference of potential the conductivity of an electrolyte is proportional to the number of ions in unit volume1 the electrical charge on each ion1 and the velocity of the ions4 ,the specific conductivity ,delta of an electrolyte is the conductivity of a cube of the solution1 each face of which is one square centimetre in area4 ,the molecular conductivity of an electrolyte is the conductivity of a solution containing one gramme-molecule of the substance placed between two parallel conducting plates1 one centimetre apart4 ,the molecular conductivity is independent of the volume occupied by the gramme-molecule of the solute1 depending only on the degree of dissociation4 ,the molecular conductivity ,u is equal to the product of ,v1 the volume of the molecule1 by ,delta1 its specific conductivity4 ,u ,v,delta4 ,whence ,delta ,u _/ ,v1 i4e4 the specific #bi conductivity equals the molecular conductivity divided by the volume4 ,the conductivity of an electrolyte is proportional to the number of ions in a volume of the solution containing one gramme-molecule4 ,let ,minfinity be the conductivity for complete dissociation and ,mv the molecular conductivity at the volume ,v4 ,then ,mv _/ ,minfinity nk _/ nk n _/ n a1 the degree of dissociation4 ,this is ,ostwald's law1 which says that the degree of dissociation is equal to the ratio of conductivity when the gramme-molecule occupies a volume ,v1 to its conductivity when the solution is so dilute that dissociation is complete4 ,hence the degree of dissociation may also be determined by comparing the electrical conductivities of two solutions of different degrees of concentration4 -- -- -- -- -- -- ,,so#d ,,so#d ,,so#d ,,so#d ,,so#d ,,so#d ,cu ,cu ,cu ,cu ,cu ,cu ---------------------------------------- -------------------- ,,fig4 #a4--;,before the passage of the current4 -- -- -- ,,so#d ,,so#d ,,so#d ,,so#d ,,so#d ,,so#d - ,cu ,cu ,cu ,cu ,cu ,cu ---------------------------------------- -------------------- ,,fig4 #b4--;,after the passage of the current4 ,velocity of the ,ions4--,if the electrolytic cell is divided into two segments by means of a porous diaphragm1 we shall find after a time an unequal distribution of the solute on the two sides4 ,for instance1 with a solution of sulphate of copper1 after the current has passed for some time there will be a diminution of concentration in the liquid on both sides of the diaphragm1 but the loss will be very unequally divided4 ,two-thirds of the loss of concentration will be on the side of the negative electrode and only one-third on the positive side4 ,in #ahec1 ,hittorf gave the following ingenious explanation of this phenomenon3-- #cj ,fig4 #a represents an electrolytic vessel containing a solution of sulphate of copper1 the vertical line indicating a porous partition separating the vessel into two parts4 ,fig4 #b shows the same vessel after the passage of the current4 ,the acid radical has travelled twice as fast as the metal4 ,for each copper ion which has passed through the porous plate towards the cathode two acid radicals have passed through it towards the anode4 ,three ions have been liberated at either electrode1 but in consequence of the difference of velocity with which the positive and the negative ions have travelled1 the negative side of the vessel contains only one molecule of copper sulphate and has lost two-thirds of its molecular concentration1 while the positive side contains two molecules of copper sulphate and has only lost one-third of its concentration4 ,this proves clearly that the ions move in different directions with different velocities4 ,let u be the velocity of the anions1 and v the velocity of the cations4 ,let n be the loss of concentration at the cathode1 and #a - n the loss of concentration at the anode4 ,then u _/ v n _/ 7#a - n71 i4e4 the loss of concentration at the cathode is to the loss of concentration at the anode as the velocity of the anions is to that of the cations4 ,hence by measuring the loss of concentration at the two electrodes1 we have an easy means of determining the comparative velocity of different ions4 ,in #ahgf1 ,kohlrausch compared the conductivity of the chlorides1 bromides1 and iodides of potassium1 sodium1 and ammonium respectively4 ,he found that altering the cation did not affect the differences of conductivity between the three salts1 thus showing that these differences of conductivity were dependent on the nature of the anion only1 and not on the particular base with which it was combined4 ,the difference of conductivity between an iodide and a bromide1 for example1 is the same whether potassium1 sodium1 or ammonium salts are compared4 ,a similar experiment has been made with a series of cations combined with various anions4 ,the difference of conductivity of the salts in the series is the same whichever anion is used1 i4e4 the difference of conductivity between potassium chloride and sodium chloride is the same as that between #ca potassium bromide and sodium bromide4 ,hence we may conclude that the conductivity of any salt is an ionic property4 ,kohlrausch's law may be expressed by the formula c d7u v71 where c is the conductivity of the salt1 d the degree of dissociation1 i4e4 the fraction of the electrolyte broken up into ions1 and u and v the velocity of the anions and cations respectively4 ,when all the molecules of the electrolyte are dissociated1 d #a1 and the formula becomes cinfinity u v4 ,as we have already seen1 a salt is formed by the union of a metal ,m with an acid radical ,r4 ,potassium sulphate1 ,k#b,,so#d1 consists of the metal ,k#b and the acid radical ,,so#d4 ,ammonium chloride1 ,,nh#d;,cl1 consists of the basic radical ,,nh#d and the acid radical ,cl4 ,the various acids may be considered as salts of the metal hydrogen4 ,thus sulphuric acid1 ,h#b,,so#d1 is the sulphate of hydrogen4 ,bases may be considered as salts with the hydroxyl group1 ,,oh1 replacing the acid radical4 ,thus potash1 ,,koh1 is the hydroxyl of potassium4 ,the various electrolytic combinations may be represented by the following symbols3-- ,salts ,,mr4 ,acids ,,hr4 ,bases ,,moh4 ,the various chemical reactions of an electrolyte are all ionic reactions1 the chemical activity of an electrolytic solution being proportional to its electric conductivity1 i4e4 the degree of dissociation of its ions4 ,the acidity of an electrolytic solution is due to the presence of the dissociated ion ,h1 and its strength is determined by the concentration of these free hydrogen ions4 ,hence the greater the degree of dissociation the stronger the acid4 ,the basic character of a solution is determined by the presence of the hydroxyl radical ,,oh-4 ,the greater the concentration of the hydroxyl ions1 i4e4 the greater the dissociation1 the stronger is the base4 ,the ions ,h and ,,oh- are of special importance1 since they are the ions of water1 ,h#b,o ,h ,,oh-4 ,the degree of #cb dissociation of pure water is but small4 ,water is1 however1 the most important of all the various agents in the chemical reactions of life1 since a large number of organic substances are decomposed by water by a process of hydrolysis1 and a vast number of organic substances are but combinations of carbon with the ions ,h and ,,oh-1 their diversity being due to variations in the relative proportions and grouping4 ,the ,chemical1 ,therapeutic1 and ,toxic ,actions of ,ions4--,the chemical1 therapeutic1 antiseptic1 and toxic actions of electrolytic solutions are almost exclusively due to ionization4 ,take1 for instance1 a solution of nitrate of silver in which the addition of chlorine produces a white precipitate of chloride of silver4 ,this precipitate occurs only when the solution added is one such as ,na,cl1 where the chlorine is present as the free ion ,cl-4 ,no such precipitate is produced in a solution of chlorate of potassium or chloracetic acid1 where the chlorine is entangled in the complex ion ,cl,o#c or ,c#b;,h#c;,cl,o#b4 ,since1 then1 the toxic and pharmacological properties of an electrolyte depend entirely on the ionic grouping1 it behoves the physician and the biologist to study the structure and grouping of the ions in a molecule1 rather than that of the atoms4 ,consider for a moment the totally different properties of the phosphides and the phosphates4 ,the former are extremely toxic1 while the latter are perfectly harmless4 ,there is not the slightest analogy between their actions on the living organism4 ,on the other hand1 all the phosphides produce the same toxic and therapeutic effects1 whatever the cation with which they are united4 ,their toxic properties are derived from the presence of the free phosphorus ion ,p---4 ,the phosphates contain phosphorus in the same proportion as the phosphides1 but this phosphorus is harmlessly entangled in the complex ion ,,po#d---1 whose properties are absolutely different from those of the ion ,p---4 ,the above considerations apply equally to the chlorides and chlorates1 the iodides and iodates1 the sulphides and sulphates1 and in general to all chemical salts4 #cc ,the question has an intimate bearing on practical pharmacology4 ,when we prescribe a cacodylate or an amylarsinate1 we are not prescribing an arsenical treatment whose effects can be compared with those of an arsenide1 an arsenite1 or an arsenate4 ,this fact is sufficiently indicated by the difference in the toxic doses of the different salts4 ,each variety of arsenical ion has its own special physiological and therapeutic properties4 ,we do not expect to obtain the results of a ferruginous treatment from the administration of a ferrocyanide or a ferricyanide4 ,both contain iron1 it is true1 but neither possess the properties of the cation ,fe1 but rather those of the complex anion of which they form a part4 ,we have already said that most of the therapeutic1 toxic1 and caustic actions of an electrolyte are due to ionic action1 and the substances can therefore have no toxic action unless they are dissociated4 ,many of the solvents employed in medicine1 such as alcohol1 glycerine1 vaseline1 and chloroform dissolve the electrolytes but do not dissociate them into ions1 and these solutions therefore do not conduct electricity4 ,such solutions have no therapeutic action4 ,with the absence of dissociation all the ionic toxic and caustic effects also disappear entirely1 and only re-appear as the water of the tissue is able slowly to effect the necessary dissociation4 ,carbolic acid dissolved in glycerine is hardly caustic and but very slightly toxic4 ,we have met with several instances in which a tablespoonful of carbolized glycerine1 in equal parts1 has been swallowed without any ill effect1 either caustic or toxic1 whereas the same dose dissolved in water would have been fatal4 ,this absence of dissociation has enabled the surgeon ,menciere to inject carbolic and glycerine in equal proportions into the larger joints1 the part being subsequently washed out with pure alcohol4 ,thus by employing vaseline1 oil1 or glycerine as a solvent1 and avoiding the access of water1 we are able to use electrolytic antiseptics in very concentrated form4 ,their action is brought out very slowly1 as the water of the organism effects the necessary dissociation of the electrolyte4 #cd ,since all chemical1 toxic1 and therapeutic actions are ionic1 they are proportional to the degree of ionic concentration1 i4e4 to the number of ions in a given volume4 ,the only point of importance1 that which determines their activity1 whether chemical or therapeutic1 is the degree of ionization or dissociation4 ,for example1 all acids have the same cation ,h4 ,they have all identical properties1 but they differ widely in the intensity of their action4 ,there are weak acids such as acetic acid1 and strong acids like sulphuric acid4 ,the stronger acids are those which are more thoroughly dissociated1 and in which the ion ,h is very concentrated2 whereas the feeble acids are but slightly dissociated1 so that the ion ,h is less concentrated4 ,paul and ,kroenig have shown that the bactericidal action of different salts also varies with their degree of dissociation1 i4e4 with the concentration of the active ions4 ,they made a series of observations on the bactericidal action of various salts of mercury1 the bichloride1 the bibromide1 and the bicyanide1 on the spores of ,bacillus anthracis4 ,the following results were obtained from a comparison of solutions containing #a gramme-molecule of the salt in #fd litres of water4 ,with the bichloride solution1 after exposure to the solution for twenty minutes1 only #g colonies of the bacillus were developed4 ,after exposure to a similar solution of the bibromide the number of colonies was #cd4 ,the antiseptic action of the bichloride was therefore five times as great as that of the bibromide4 ,the bicyanide of mercury1 however1 even when four times as concentrated1 permitted the growth of an enormous number of colonies1 showing that it had no appreciable antiseptic action whatever4 ,nevertheless1 the proportion of ,hg is the same in all the solutions1 and if there were any difference one would naturally expect that the ion ,cy- would be more toxic than ,cl- or ,br-4 ,the real condition which varies in these solutions and determines their activity is the degree of dissociation4 ,the whole of the antiseptic property resides in the ion ,hg4 ,this ion is very #ce concentrated in the highly dissociated solution ,hg,cl#b1 less concentrated in the less ionized solution ,hg,br#b1 and exceedingly dilute in the ,hg,cy#b1 which is hardly ionized at all4 ,what is true of the bactericidal action of the salts of mercury is equally true of their therapeutic effect4 ,it is a great mistake to estimate the medicinal activity of a solution of a salt of mercury1 or indeed of any electrolytic solution1 simply by its degree of molecular concentration4 ,the important point is the degree of dissociation1 which is the only true measure of its activity4 ,in the intramuscular injection of mercury salts it is by no means a matter of indifference what salt we employ4 ,a salt should be used such as the bichloride or the biniodide1 which is easily dissociated4 ,other salts are often employed because they occasion less pain at the site of injection2 but the pain is a sign of the degree of activity of the preparation4 ,the pain1 it is true1 may be avoided by using a salt which is less easily dissociated1 or in which the mercury is bound up in a complex ion1 but by so doing we diminish the efficacy of the remedy4 ,it is moreover quite easy to diminish1 or even entirely to suppress1 the pain1 by using a very dilute solution of an active ionized salt4 ,a one-half per cent4 or even one-quarter per cent4 solution of the bichloride or biniodide of mercury may be injected very slowly in sufficient quantity without producing the slightest discomfort4 ,local action depends entirely on ionic concentration4 ,one drop of pure sulphuric acid will destroy the skin1 whereas the same amount if diluted in a tumblerful of water will furnish a refreshing drink4 99 99 99 99 99 #cf ,,chapter ,,iv ,,colloids ,as we have already seen1 living organisms are formed essentially of liquids4 ,these liquids are solutions of crystallizable substances or crystalloids1 and non-crystallizable substances or colloids--a classification which we owe to ,graham4 ,the liquids are the most important constituents of a living organism1 since they are the seat of all the chemical and physical phenomena of life4 ,the junction of two liquids of different concentration is the arena in which takes place both the chemical transformation of matter and the correlative transformation of energy4 ,in a former chapter we have passed in review the class of crystalloids1 we will now turn our attention to the characteristic properties of colloids4 ,colloids4--,colloids differ from crystalloids in that they do not form crystals from solution1 being completely amorphous when in the solid state4 ,the solution of a colloid solidifies in the same form which it possessed in the liquid state1 the solvent being enclosed in the meshes of a sort of network formed by the solute4 ,this form is approximately retained even after the water has evaporated by drying1 the passage from the liquid state of solution to the solid state being effected through a series of intermediary states1 such as a clot1 coagulum1 or jelly4 ,this passage from the state of solution into a state of jelly is called coagulation4 ,some colloids1 such as gelatine1 coagulate with cold2 while others1 such as egg-albumin1 coagulate with heat4 ,some1 like the caseine of milk1 require the addition of certain chemical substances to set up coagulation2 while still others1 such as the fibrin of blood1 appear to coagulate spontaneously4 ,the physical phenomena of #cg coagulation are still but little understood4 ,in some cases it is a reversible phenomenon1 thus gelatine coagulated by cold is redissolved by heat2 whereas with other colloids the process is irreversible1 albumin coagulated by heat is not redissolved on cooling4 ,colloids in a state of coagulation have a vacuolar or sponge-like structure4 ,the solvent is imprisoned in the vacuoles of the clot1 and is expelled little by little by its retraction4 ,colloids diffused in water are usually called colloidal solutions1 but they are not true solutions4 ,such a pseudo-solution of a colloid is called a sol1 while a colloid in a state of coagulation is called a gel4 ,colloidal solutions spread but little1 diffuse very slowly in the liquids of the body1 and cannot penetrate organic membranes4 ,colloidal solutions diffuse light1 unlike crystalloid solutions1 which are transparent4 ,we all know how the trajectory of a beam of sunlight through a darkened room is rendered visible by the particles of dust4 ,in the same way if a colloidal solution is illuminated by a transverse ray of light1 the light is diffused by the molecules of the colloid in semi-solution1 and the liquid appears faintly illuminated on a dark background4 ,the light diffused by a colloidal solution is polarized1 which shows that it is reflected light1 ,siedentopf and ,sigmondy have applied this principle of lateral illumination on a dark background to the construction of the ultra-microscope4 ,with the aid of this instrument we may not only see1 but count the particles in a colloidal solution1 which is in reality merely a pseudo-solution or suspension1 in contradistinction to the true solution of a crystalloid4 ,colloidal solutions possess only a very feeble osmotic pressure4 ,the lowering of the freezing point and the other corresponding constants are also quite insignificant4 ,this arises from the fact that the molecules of a colloid are extremely large when compared with those of a crystalloid4 ,for example let us take colloidal substance whose molecular weight is #bjjj4 ,a solution containing #dj grammes per litre would have an osmotic pressure only one-fiftieth of that of a #ch solution of similar strength of a crystalloid whose molecular weight was #dj4 ,not only so1 but on measuring the molecular concentration1 the osmotic pressure1 and the other constants of a colloidal solution1 we find values even lower than those which we should expect from a consideration of its molecular weight4 ,this is probably due to the tendency of a colloid to polymerization1 i4e4 to form groups or associations of molecules4 ,suppose1 for instance1 that the molecules of a colloidal solution are aggregated into groups of ten4 ,since each group plays the part of a simple molecule1 the osmotic pressure will be ten times less than that corresponding to the quantity of the solute present4 ,such a group of molecules is called by ,naegeli a micella4 ,similar phenomena of aggregation may be observed in the molecules of many inorganic substances4 ,the molecule of iodine1 for example1 is monatomic at #abjj;deg ,c41 but becomes diatomic at the ordinary temperature4 ,sulphur at #hfj;deg ,c4 is a gas with a vapour density of #b4b1 while at #ejj;deg ,c4 its vapour density rises to #f4f4 ,in both of these cases two or more molecules of the element have been condensed into one as a result of the fall of temperature4 ,we frequently find that two successive cryoscopic observations on the freezing point of the same colloidal solution will vary4 ,this is due to the extreme sensitiveness of the micellae1 which absorb or abandon their extra molecules under the slightest influence4 ,this mobility in the constitution of the micellae appears to be one of the principal causes of the peculiar properties of colloidal solutions4 ,the phenomenon of polymerization appears to be reversible4 ,the micellae are formed under certain conditions1 and are disintegrated when these conditions are removed4 ,the osmotic pressure varies in the same manner1 diminishing with polymerization and augmenting with the disintegration of the micellae4 ,one may easily understand what an important role is played by this alternate polymerization and disintegration in the phenomena of life4 ,most colloidal substances are precipitated from their solutions by the addition of very small quantities of electrolytic #ci solutions4 ,non-electrolytic solutions do not appear to provoke this precipitation4 ,this is not a chemical action1 for an exceedingly small quantity of an electrolyte is able to precipitate an indefinite quantity of the colloid4 ,the precipitation is probably due to the electric charges carried by the dissociated ions of the electrolytes4 ,when an electric current is passed through a colloid solution1 the course of the molecules of the colloid is sometimes towards the cathode and sometimes towards the anode1 according to the nature of the colloid and of the solvent4 ,this displacement would appear to indicate a difference of electric potential between the molecules of the colloid and those of the solvent4 ,hardy has shown that in an alkaline solution the molecules of albumin travel towards the anode1 while in an acid solution they travel towards the cathode4 ,metallic ,colloids4--,carey ,lea and afterwards ,crede succeeded in obtaining silver in colloidal solution by ordinary chemical means4 ,professor ,bredig has introduced a more general method of obtaining a number of metals in colloidal solutions in a state of great purity4 ,he causes an electric arc to pass between two rods of the metal immersed in distilled water4 ,the cathode is thus pulverized into a very fine powder which rests in suspension in the liquid1 constituting a colloidal solution4 ,bredig has in this way prepared sols of platinum1 palladium1 iridium1 silver1 and cadmium4 ,catalytic ,properties of ,colloids4--,catalysis is the property possessed by certain bodies of initiating chemical reaction4 ,the mass of the catalyzing body has no definite proportion to that of the substances entering into the reaction1 and the appearance of the catalyzer is in no way altered by the reaction4 ,ostwald has shown that catalysis consists essentially in the acceleration or retardation of chemical reactions which would take place without the action of the catalyzer1 but more slowly4 ,catalytic reactions are very numerous in chemistry4 ,the inversion of sugar by acids1 the etherization of alcohol by sulphuric acid1 the decomposition of hydrogen peroxide by #dj platinum black are all instances of catalysis4 ,fermentation by means of a soluble ferment or diastase1 a phenomenon which may almost be called vital1 is also a catalytic action4 ,the action of pepsin1 of the pancreatic ferment1 of zymase1 and of other similar ferments has a great analogy with the purely physical phenomenon of catalysis4 ,the diastases are all colloids1 and so are many other catalyzers4 ,a catalyzer is a stimulus which excites a transformation of energy4 ,the catalyzer plays the same role in a chemical transformation as does the minimal exciting force which sets free the accumulation of potential energy previous to its transformation into kinetic energy4 ,a catalyzer is the friction of the match which sets free the chemical energy of the powder magazine4 ,bredig has studied the catalytic decomposition of hydrogen peroxide by metallic colloids prepared by his electric method4 ,he found that #a atom-gramme of colloidal platinum gives a sensible catalytic effect when diluted with #gj million litres of water4 ,caustic soda and other chemical substances inhibit the catalytic action of colloidal platinum in the same way as they inhibit the fermenting action of diastase4 ,the curve of decomposition of hydrogen peroxide by colloidal platinum may be compared with the curve of fermentation by emulsin4 ,both are equally affected by the addition of an alkali4 ,many other chemical and physical agents have a similar inhibitory action on the catalysis of colloidal metals and on diastasic fermentation4 ,thus a mere trace of sulphuretted hydrogen or hydrocyanic acid will paralyse the action of a colloidal metal1 just as it does that of a ferment4 ,this is what ,bredig calls the poisoning of metallic ferments4 ,we may hope that the further study of catalysis1 a purely physico-chemical phenomenon1 may throw more light on the mechanism of diastasic fermentation1 which is essentially a vital reaction4 ,it must not be forgotten that all classification is artificial and arbitrary1 and only to be used as long as it facilitates study4 ,this observation is particularly applicable to the classification of substances into crystalloids and colloids4 #da ,there is no sharp line between the two groups1 the passage is gradual1 and it is impossible to say where one group ends and the other begins4 ,many colloids such as haemoglobin are crystallizable1 and many crystallizable substances are coagulable4 ,many substances appear at one time in the crystalloid state and at another time in the colloidal state1 so that instead of dividing substances into colloids and crystalloids1 we should rather consider these expressions as denoting different phases assumed by the same substance4 ,in order to define clearly our various classes and divisions1 we are apt to exaggerate slight differences of properties or composition4 ,we say that colloids have no osmotic pressure1 whereas in fact the osmotic pressure of the colloids though feeble plays a very important part in the phenomena of life4 ,so in other departments of science--a factor which is almost infinitesimal may yet exercise a vast influence on the results4 ,it is by infinitesimal variations of pressure1 a thousandth of a millimetre or less1 that we obtain the various degrees of penetration in the ,roentgen rays4 ,the division into solutions and pseudo-solutions or suspensions is also an arbitrary one4 ,a true solution is also a suspension of the molecules of the solute4 ,there is no essential difference between a solution and a suspension1 but only a difference in the size of the molecules1 or agglomerations of molecules1 in one case so small as to be transparent1 and in the other case just big enough to diffuse light4 ,there are moreover many properties common to colloidal solutions and suspensions of fine powders1 such as kaolin1 mastic1 charcoal1 or ,indian ink4 ,these particles in suspension are precipitated by solutions of electrolytes in a manner similar to the coagulation of colloids4 ,the surface of every liquid is covered by a very thin layer1 a sort of membrane slightly differentiated from the rest of the liquid4 ,this membrane may be a chemical one1 a pellicular precipitate like that which is formed by the contact of two membranogenous liquids4 ,on the other hand1 the membrane may not differ from the subjacent liquid in chemical composition1 but only in physical properties4 ,if we #db consider the molecules in the middle of a liquid1 each molecule is subjected to the cohesive attraction of molecules on every side1 attractions which neutralize one another4 ,at the surface of the liquid1 however1 there are quite other conditions of equilibrium4 ,there each molecule is drawn downwards towards the centre of the liquid1 and there is no compensating attraction in an opposite direction4 ,the resultant pressure is normal to the surface of the liquid1 and is mechanically equivalent to an elastic membrane which tends to diminish the surface1 and hence the volume of the liquid4 ,we may therefore regard this surface tension as acting the part of a veritable physical membrane4 ,there is a still further differentiation of the surface of a liquid4 ,when the liquid is not a simple one1 but complex as in a solution1 we find that the concentration of the solute is greater at the surface than in the interior4 ,this is the so-called phenomenon of adsorption1 which is another cause for the production of a physical membrane covering the surface of a liquid4 ,substances in a colloidal state have a great tendency to form these chemical or physical membranes at the point of contact between the colloidal solute and the solvent4 ,this is probably the reason why the coagulum of a colloidal liquid usually presents a vacuolar or spongy structure4 99 99 99 99 99 #dc ,,chapter ,v ,,diffusion ,,and ,,osmosis ,diffusion and ,osmosis4--,if we place a lump of sugar in the bottom of a glass of water1 it will dissolve1 and spread by slow degrees equally throughout the whole volume of the liquid4 ,if we pour a concentrated solution of sulphate of copper into the bottom of a glass vessel1 and carefully pour over it a layer of clear water1 the liquids1 at first sharply separated by their difference of density1 will gradually mix1 so as to form a solution having exactly the same composition in all parts of the jar4 ,the process whereby the sugar and the copper sulphate spread uniformly through the whole mass of the liquid in opposition to gravity is called ,diffusion4 ,this diffusion of the solute is a phenomenon exactly analogous to the expansion of a gas4 ,it is the expression of osmotic pressure1 or rather of the difference of the osmotic pressure of the solute in different parts of the vessel4 ,the molecules of the solute move from a place where the osmotic pressure is greater towards a position where the osmotic pressure is less4 ,the water molecules on the other hand pass from positions where the osmotic pressure of the solute is less towards positions where it is greater4 ,as a consequence of this double circulation the osmotic pressure tends to become equalized in all parts of the vessel4 ,diffusion appears to be the fundamental physical phenomenon of life4 ,it is going on continually in the tissues of all living beings1 and a study of the laws of diffusion and osmosis is therefore absolutely necessary for a just conception of vital phenomena4 ,coefficient of ,diffusion4--,the coefficient of diffusion has #dd been defined by ,fick as the quantity of a solute which in one second traverses each square centimetre of the cross section of a column of liquid #a centimetre long1 between the opposite sides of which there is unit difference of concentration4 ,nernst in his definition substitutes unit difference of osmotic pressure for unit difference of concentration4 ,until recently it was generally believed that diffusion took place in colloids and plasmas just as in pure water4 ,this is1 however1 by no means the case3 the differences are considerable4 ,when a solute is introduced into a colloidal solution1 the greater the concentration of the colloid the slower will be the diffusion4 ,this may be shown by a simple experiment4 ,several glass plates are prepared1 by spreading on each a solution of gelatine of different concentration1 to which a few drops of phenol phthalein have been added4 ,if now a drop of an alkaline solution be placed on each plate1 we can see that the drop diffuses more slowly through the more concentrated gelatine solution1 since the presence of the alkali is rendered visible by the coloration of the phenol phthalein4 ,a similar demonstration may be made by allowing drops of acid to diffuse through solutions of gelatine made slightly alkaline and coloured with phenol phthalein4 ,in general1 we find on experiment that when similar drops of any coloured or colouring solution are left for an equal time on plates of gelatine of different degrees of concentration1 the greater the concentration of the gelatine the smaller will be the circle of coloration obtained4 ,we may show that the rapidity of diffusion diminishes as the gelatinous concentration increases1 by another experiment4 ,if we put side by side on our gelatine plate a drop of sulphate of copper and another of ferrocyanide of potassium1 the point of contact of the two fluids will be sharply marked by a line of precipitate4 ,we find that under similar conditions the time between the sowing of the drops and the formation of this line of precipitate is longer when the gelatine is more concentrated4 ,osmosis4--,in #agdh1 l',abbe ,nollet discovered that when a pig's bladder filled with alcohol was plunged into water1 the #de water passed into the bladder more rapidly than the alcohol passed out2 the bladder became distended1 the internal pressure increased1 and the liquid spirted out when the bladder was pricked by a pin4 ,this passage of certain substances in solution through an animal membrane is called ,osmosis1 and membranes which exhibit this property are called osmotic membranes4 ,precipitated ,membranes4--,in #ahfg1 ,traube of ,breslau discovered that osmotic membranes could be made artificially4 ,certain chemical precipitates such as copper ferrocyanide can form membranes having properties analogous to those of osmotic membranes4 ,with these precipitated membranes ,traube made a number of interesting experiments4 ,these have lately been collected in the volume of his memoirs published by his son4 ,osmotic ,membranes4--,osmotic membranes were formerly called semi-permeable membranes1 being regarded as membranes which allow water to pass through them1 but arrest the passage of the solute4 ,this definition is inexact1 since no membrane permeable to water is absolutely impermeable to the solutes4 ,all we can say is that certain membranes are more permeable to water than to the substances in solution1 and are moreover very unequally permeable to the various substances in solution4 ,as a rule a membrane is much more permeable to a solute whose molecule is of small dimensions4 ,molecules of salt1 for instance1 pass through such a membrane much more quickly than do those of sugar4 ,the term osmotic membrane should therefore in all cases replace that of semi-permeable membrane4 ,osmotic membranes behave exactly like colloids4 ,the resistance which they oppose to the passage of different substances varies with the nature of the liquid or solute concerned4 ,there is no real difference between the passage of a solution through an osmotic membrane and its diffusion through a colloid4 ,the protoplasm of a living organism1 being a colloid1 acts exactly like an osmotic membrane so far as regards the distribution of solutions and substances in solution4 #df ,the diffusion of molecules through a colloid1 a plasma1 or a membrane is governed by laws precisely analogous to ,ohm's law1 which governs the transport of electricity4 ,the intensity or rapidity of diffusion is proportional to the difference of osmotic pressure1 and varies inversely with the resistance4 ,in the case of molecular diffusion1 however1 the rapidity of diffusion depends also on the size and nature of the molecules of the diffusing substance4 ,the theory of the resistance of the various plasmas and membranes to diffusion has been but little understood2 we can discover hardly any reference to it in the literature of the subject4 ,the laws of diffusion apply equally to the diffusion of ions4 ,nernst has shown that there is a difference of electric potential at the surface of contact of two electrolytic solutions of different degrees of concentration4 ,both the positive and negative ions of the more concentrated solution pass into the less concentrated solution1 but the ions of one sign will pass more rapidly than those of the other sign1 because being smaller1 they meet with less resistance4 ,the resistance of the medium plays a most important part in all the phenomena of diffusion4 ,when two solutions of different concentration come into contact1 the interchange of molecules and ions which occurs is unequal owing to the differences in resistance4 ,hence both solutions become modified not only in concentration but also in composition4 ,it has long been known that diffusion can cause the decomposition of certain easily decomposed substances1 and it would appear probable that diffusion is also capable of producing new chemical combinations4 ,the separation of the liberated ions in consequence of the unequal resistance which they meet with in the medium they traverse often determines chemical reaction4 ,this ionic separation is a fertile agent of chemical transformation in the living organism1 and may be the determinant cause in those chemical reactions which constitute the phenomena of nutrition4 ,when different liquids come into contact there are two distinct series of phenomena1 those due to osmotic pressure and those due to differences of chemical composition4 ,even #dg with isotonic solutions there will be a transfer of the solutes if these are of different chemical constitution4 ,take1 for instance1 two isotonic solutions1 one of salt and another of sugar4 ,when these are brought into contact there is no transference of water from one solution to the other1 but there is a transference of the solutes4 ,in the salt solution the osmotic pressure of the sugar is zero4 ,hence the difference of osmotic pressure of the sugar in the two solutions will cause the molecules of sugar to diffuse into the salt solution4 ,for the same reason the salt will diffuse into the sugar solution4 ,a disregard of this fact1 that a solute will always pass from a solution where its osmotic pressure is high1 into one where its osmotic pressure is low1 is a frequent source of error4 ,thus it is said to be contrary to the laws of osmosis that solutes should pass from the blood1 with its low osmotic pressure1 into the urine1 where the general osmotic pressure is higher2 the more so because in consequence of the exchange the osmotic pressure of the urine is still further increased4 ,such an exchange1 it is argued1 is contrary to the ordinary laws of physics1 and can therefore only be accomplished by some occult vital action4 ,this1 however1 is not the fact1 as is proved by experiment4 ,consider an inextensible osmotic cell containing a solution of sugar1 the walls of the cell being impermeable to sugar but permeable to salt4 ,let us plunge such a cell into a solution of salt1 which has a lower osmotic pressure than the sugar solution4 ,since the walls of the cell are inextensible1 the quantity of water in the cell cannot increase4 ,the salt1 however1 will pass into the cell1 since the osmotic pressure of the salt is greater on the outside than on the inside1 and the walls are permeable to the molecules of salt4 ,this passage will continue until the osmotic pressure of the salt is equal inside and outside the cell2 at the same time the total osmotic pressure within the cell will have increased1 in spite of its being originally greater than the osmotic pressure outside4 ,plasmolysis4--,we all know that a cut flower soon dries #dh up and fades4 ,when1 however1 we place the shrivelled flower in water1 the contracted protoplasm swells up again and refills the cells1 which become turgid1 and the flower revives4 ,this phenomenon is due to the fact that vegetable protoplasm holds in solution substances like sugars and salts which have a high osmotic pressure4 ,consequently water has a tendency to penetrate the cellular walls of plants1 to distend the cells and render them turgescent4 ,de ,vries has used this phenomenon for the measurement of osmotic tension4 ,he employs for this purpose the turgid cells of the plant ,tradescantia discolor4 ,the cells are placed under the microscope and irrigated with a solution of nitrate of soda4 ,on gradually increasing the concentration of the solution there comes a moment when the protoplasmic mass is seen to contract and to detach itself from the walls of the cell4 ,this phenomenon1 which is known as plasmolysis1 occurs at the moment when the solution of nitrate of soda begins to abstract water from the protoplasmic juice1 i4e4 when the osmotic tension of the nitrate of soda becomes greater than that of the protoplasmic liquid4 ,so long as the osmotic tension of the soda solution is less than that of the protoplasm1 there will be a tendency for water to penetrate the cell wall and swell the protoplasm4 ,when the osmotic tension of the solution which bathes the cell is identical with that of the cellular juice1 there is no change in the volume of the protoplasm4 ,in this way we are able to determine the osmotic pressure of any solution4 ,we have only to dilute the solution till it has no effect on the protoplasm of the vegetable cells4 ,since the osmotic tension of this protoplasm is known1 we can easily calculate the osmotic tension of the solution from the degree of dilution required4 ,red ,blood ,corpuscles as ,indicators of ,isotony4--,in #ahhf1 ,hamburger showed that the weakest solutions of various substances which would allow the deposition of the red blood cells1 without being dilute enough to dissolve the haemoglobin1 were isotonic to one another1 and also to the blood serum1 and to the contents of the blood corpuscles4 ,this is ,hamburger's method of determining the osmotic #di tension of a liquid4 ,the diluted solution is gradually increased in strength until1 when a drop of blood is added to it1 the corpuscles are just precipitated1 and no haemoglobin is dissolved4 ,the ,haematocrite4--,in #ahia1 ,hedin devised an instrument for determining the influence of different solutions on the red blood corpuscles4 ,this instrument1 the haematocrite1 is a graduated pipette1 designed to measure the volume of the globules separated by centrifugation from a given volume of blood under the influence of the liquid whose osmotic pressure is to be measured4 ,the method depends on the principle that solutions isotonic to the blood corpuscles and to the blood serum will not alter the volume of the blood corpuscles1 whereas hypertonic solutions decrease that volume4 ,action of ,solutions of ,different ,degrees of ,concentration on ,living ,cells4--,we have just seen that a living cell1 whether vegetable or animal1 is not altered in volume when immersed in an isotonic solution that does not act upon it chemically4 ,when immersed in a hypertonic solution1 it retracts2 in a slightly hypotonic solution it absorbs water and becomes turgescent1 while in a very hypotonic solution it swells up and bursts4 ,in a hypertonic solution the red blood cells retract and fall to the bottom of the glass1 the rapidity with which they are deposited depending on the amount of retraction4 ,in a hypotonic solution they swell up and burst1 the haemoglobin dissolving in the liquid and colouring it red4 ,this is the phenomenon of haematolysis4 ,according to ,hamburger1 the serum of blood may be considerably diluted with water before producing haematolysis4 ,experimenting with the blood of the frog1 he found that the globules remained intact in size and shape when irrigated with a salt solution containing 4#fd per cent4 of salt1 this solution being isotonic with the frog's blood serum4 ,on the other hand1 they did not begin to lose their haemoglobin till the proportion of salt was reduced to below 4#bb per cent4 ,thus frog's serum may be diluted with #bjj per cent4 of water before producing haematolysis4 ,in mammals the blood corpuscles remain invariable in a salt solution of about 4#i per cent41 and begin to lose their #ej haemoglobin approximately in a 4#f per cent4 solution4 ,a solution of 4#i per cent4 of ,na,cl is therefore isotonic to the contents of the red blood corpuscles1 to the serum of the blood1 and to the cells of the tissues4 ,it by no means follows that the cells of the blood and tissues undergo no change when irrigated with a 4#i per cent4 solution of chloride of sodium4 ,they do not lose or gain water1 it is true1 and they retain their volume and their specific gravity4 ,but they do undergo a chemical alteration1 by the exchange of their electrolytes with those of the solution4 ,hamburger has pointed out that in mammals the shape of the red corpuscles is altered in every liquid other than the blood serum2 even in the lymph of the same animal there is a diminution of the long diameter1 and an increase of the shorter diameter1 while the concave discs become more spherical4 ,all the cells of a living organism are extremely sensitive to slight differences of osmotic pressure--the cells of epithelial tissue and of the nervous system as well as the blood cells4 ,for instance1 the introduction of too concentrated a saline solution into the nasal cavity will set up rhinitis and destroy the terminations of the olfactory nerves4 ,pure water1 on the other hand1 is itself a caustic4 ,there is a spring at ,gastein1 in the ,tyrol1 which is called the poison spring1 the ,gift-,brunnen4 ,the water of this spring is almost absolutely pure1 hence it has a tendency to distend and burst the epithelium cells of the digestive tract1 and thus gives rise to the deleterious effects which have given it its name4 ,ordinary drinking water is never pure1 it contains in solution salts from the soil and gases from the atmosphere4 ,these give it an osmotic pressure which prevents the deleterious effects of a strongly hypotonic liquid4 ,during a surgical operation it is of the first importance not to injure the living surfaces by flooding them with strongly hypertonic or hypotonic solutions4 ,this precaution becomes still more important when foreign liquids are brought into contact with the delicate cells of the large surfaces of the serous membranes4 ,gardeners are well aware of the noxious influence of a low osmotic pressure4 ,they water the soil around the roots of a plant1 so that the water may take up #ea some of the salts from the soil before being absorbed by the plant4 ,pure water poured over the heart of a delicate plant may burst its cells owing to its low osmotic pressure4 ,in many medical and surgical applications1 on the other hand1 a low osmotic pressure is of advantage4 ,thus1 in order to remove the dry crusts of eczema and impetigo1 the most efficacious application is a compress of cotton wool soaked in warm distilled water4 ,under the influence of such a hypotonic solution the dry cells rapidly swell up1 burst1 and are dissolved4 ,cooking is also very much a question of osmotic pressure4 ,if salt is put into the water in which potatoes and other vegetables are boiled1 osmosis is set up and a current of water passes from the vegetable cells to the salt water4 ,the cellular tissue of the vegetable becomes contracted and dried1 and the membranes become adherent1 the vegetable loses weight and becomes difficult of digestion1 in consequence of its hard and waxy consistency1 which prevents the action of the digestive juices4 ,vegetables should be cooked in soft water1 and should be salted after cooking4 ,when so treated1 a potato absorbs water1 the cells swell up1 the skin bursts1 the grains of starch also swell up and burst1 and the pulp becomes more friable4 ,the digestive juice is thus able to penetrate the different parts of the vegetable rapidly1 and digestion is facilitated4 ,any one can easily prove for himself that a potato boiled in salt water diminishes in weight1 whilst its weight increases when it is cooked in soft water4 ,the method of cryoscopy is also of considerable service in forensic medicine4 ,as shown by ,carrara1 the cryoscopy of the blood is an important aid in determining the question whether a body found in the water was thrown in before or after death4 ,in the former case the concentration of the blood will be much diminished4 ,in certain experiments on dogs the cryoscopic examination of the blood showed a freezing point of -4#f;deg ,c4 ,the dog was then drowned1 when the freezing point of the blood in the left ventricle was increased to -4#bi;deg ,c41 and that in the right ventricle to -4#db;deg ,c4 ,on the other hand1 when a dog was killed before being thrown into the water1 the #eb osmotic pressure of the blood was hardly decreased even after an immersion of #gb hours4 ,in the case of persons or animals drowned in sea water1 a similar alteration of the point of congelation is observed1 but in the reverse direction4 ,in this case the osmotic pressure is raised considerably in those who are drowned1 whereas no such rise is observed in those who are thrown into the sea after death4 ,the circulation of the sap in plants and trees is also in great part due to osmotic pressure4 ,the aspiration of the water from the soil is due to the intracellular osmotic pressure in the roots1 which causes the sap to rise in the stem of a plant as it would in the tube of a manometer4 ,from a knowledge of the osmotic pressure of the intracellular liquid of the roots1 we may calculate the height to which the sap can be raised in the trunk of a tree1 i4e4 the maximum height to which the tree can possibly grow4 ,suppose1 for instance1 the plasma of the rootlets has an osmotic pressure of six atmospheres1 corresponding to that of a #i per cent4 solution of sugar4 ,a pressure of six atmospheres is equal to the weight of a column of water #f x 4#gf x #ac4eif #fa4ie metres high4 ,this1 then1 is the maximum height to which this osmotic pressure is able to lift the sap4 ,that is to say1 a tree whose rootlets contain a solution of sugar of #i per cent4 concentration1 or its equivalent1 can grow to a height of #fb metres4 ,cryoscopy is also of great use in practical medicine1 more especially for the examination of the urine4 ,the freezing point of urine varies from -#a4bf;deg ,c4 to -#b4ce;deg4 ,koryani has studied the ratio of the point of congelation of urine to that of a solution containing an equal quantity of chloride of sodium4 ,he finds that the ratio 7freezing point of urine7 _/ 7freezing point of ,na,cl7 increases when the circulation through the tubules of the kidney is diminished4 ,hans ,koeppe has shown that the hydrochloric acid of the gastric juice is produced by the osmotic exchanges between the blood and the gastric contents4 ,the ion ,na of the salt in the stomach contents exchanges with an ion ,h of the monobasic salts of the blood1 ,na,h,c,o#c ,na,cl ,h,cl ,na#b;,,co#c4 #ec ,influence of ,muscular ,contraction on the ,intramuscular ,osmotic ,pressure4--,when a muscle is immersed in an isotonic salt solution it does not change in weight4 ,in a hypertonic solution it loses weight in consequence of a loss of water1 which passes from the muscle into the solution to equalize the osmotic pressure4 ,it gains weight in a hypotonic solution1 the water current setting towards the point of higher concentration4 ,it is easy1 therefore1 to tell whether the osmotic pressure in a muscle is above or below that of a given solution1 by observing whether the muscle gains or loses weight when immersed in it4 ,thus we may measure the osmotic pressure in a muscle by finding a salt solution in which the muscle neither gains nor loses weight4 ,in this way we have been able to prove that the osmotic pressure of a tired muscle is higher than that of the normal muscle4 ,our experiments were carried out on the muscles of frogs4 ,after having pithed the frog1 one of the hind legs is removed by a single stroke of the scissors4 ,the leg is skinned1 dried with blotting paper1 and weighed4 ,it is then placed in a salt solution whose freezing point is -4#ec;deg ,c4 ,at #ae;deg ,c4 such a solution has an osmotic pressure of #f4f atmospheres4 ,we next proceed to determine the osmotic pressure of the corresponding leg after it has been tired by muscular work4 ,for this it is stimulated by an intermittent faradic current passing once a second for five minutes4 ,the leg is then skinned1 dried1 weighed1 and placed in the same salt solution4 ,after eight hours' immersion the legs are weighed again4 ,the following are the results of six experiments1 the numbers representing fractions of the original weight3-- ,change of weight of untired leg-- ,after #h hours -4#jjj4 ,after #af hours -4#jjj4 ,after #bd hours -4#jjf4 ,change of weight of stimulated leg-- ,after #h hours 4#jej4 ,after #af hours 4#jhj4 ,after #bd hours 4#aja4 #ed ,this result shows that muscular work provoked by electric stimulation noticeably increases the osmotic pressure of the muscle4 ,in order to discover the exact osmotic pressure in the stimulated muscles we repeated the series of experiments1 using more and more concentrated solutions4 ,in a solution whose freezing point was -4#eg;deg1 we obtained the following values3-- ,change of weight of untired leg-- ,after #h hours -4#jjj4 ,after #af hours -4#jjd4 ,after #bd hours -4#jjf4 ,change of weight of stimulated leg-- ,after #h hours 4#jci4 ,after #af hours 4#jgb4 ,after #bd hours 4#jii4 ,finally1 in a solution freezing at -4#gb;deg1 i4e4 with an osmotic pressure at #ae;deg ,c4 of #i4agf atmospheres1 we obtained the following mean values for the untired leg3-- ,after #h hours -4#jd4 ,after #af hours -4#je4 ,after #bd hours -4#je4 ,in this solution1 freezing at -4#gb;deg ,c41 some of the stimulated muscles showed no diminution in weight1 while others showed a very small diminution1 and others again a slight augmentation1 the maximum increase being 4#jhe of the initial weight4 ,the solution is therefore practically isotonic with the stimulated muscle4 ,in this case the elevation of the intramuscular osmotic pressure produced by the electrical excitation and the muscular contractions was therefore #b4e atmospheres1 or more than #b4f kilogrammes per square centimetre of surface4 ,i made further experiments in order to discover whether the variation in osmotic pressure depended on the duration of #ee the muscular contraction4 ,for this purpose ,i used a solution freezing at -4#ec;deg ,c4 and immersed in it untired muscles1 and muscles which had been electrically excited for two1 four1 and six minutes respectively4 ,the following are the results3-- ,untired muscles4 ,muscles stimulated once a second during #b ,minutes4 #d ,minutes4 #f ,minutes4 4#jjj 4#jbf 4#jhd 4#jid 4#jja 4#jcd 4#jfe 4#jic 4#jje 4#jde 4#jgi 4#jig 4#jjj 4#jcg 4#jgj 4#jie 4#jjj 4#jcb 4#jgb 4#jif ,mean of all the observations-- 4#jjab 4#jcdh 4#jgd 4#jie ,these experiments show clearly that the osmotic intramuscular pressure rises in proportion to the duration of the electrical stimulation4 ,in order to determine the influence of the work accomplished by the muscle on the elevation of the osmotic pressure1 ,i made the following experiment4 ,the two hind legs of a frog were submitted to the same electrical excitation1 one leg being left at liberty1 and the other being stretched by a hundred-gramme weight1 acting by a cord and pulley4 ,after exciting them electrically for five minutes1 the legs were immersed for twenty-four hours in a saline solution freezing at 4#ec;deg ,c4 ,the free limb showed an augmentation of 4#jhe of the initial weight1 and the stretched limb an increase of 4#ajf of the initial weight4 ,it is evident1 therefore1 that the osmotic pressure increases with the amount of work done by a muscle4 ,briefly1 then1 the results of our experiments are as follow3-- #a4 ,muscular contraction electrically produced causes an increase of the osmotic pressure in a muscle4 #b4 ,the intramuscular osmotic pressure may reach1 or even exceed1 #b4e atmospheres1 or #b4f kilogrammes per square centimetre of surface4 #c4 ,when a muscle is made to contract once a second1 the #ef elevation of the osmotic pressure increases with the number of contractions4 #d4 ,the intramuscular osmotic pressure increases with the work done by the muscle4 #e4 ,fatigue is caused by the increase of osmotic pressure in a contracting muscle4 ,illustration3 ,,fig4 #c4--;,fields of diffusive force4 7a7 ,monopolar field of diffusion4 ,a drop of blood in a saline solution of higher concentration4 7b7 ,bipolar field of diffusion4 ,two poles of opposite signs4 ,on the right a grain of salt forming a hypertonic pole of concentration1 on the left a drop of blood forming a hypotonic pole of dilution4 ,the ,field of ,diffusion4--,just as ,faraday introduced the conception of a field of magnetic force and a field of electric force to explain magnetic and electrical phenomena1 so we may elucidate the phenomena of diffusion by the conception of a field of diffusion1 with centres or poles of diffusive force4 ,if we consider a solution as a field of diffusion1 any point where the concentration is greater than that of the rest may be considered as a centre of force1 attractive for the molecules of water1 and repulsive for the molecules of the solute4 ,in the same way any point of less concentration may be regarded as a centre of attraction for the molecules of the solute1 and a centre of repulsion for the molecules of water4 ,a field of diffusion may be monopolar or bipolar4 ,a bipolar field has a hypertonic pole or centre of concentration1 and a hypotonic pole or centre of dilution4 ,by analogy with the magnetic and electric fields we may designate the hypertonic pole as the positive pole of diffusion1 and the hypotonic as the negative pole4 #eg ,the positive and negative poles and the lines of force in the field of diffusion may be illustrated by the following experiment4 ,a thin layer of salt water is spread over an absolutely horizontal plate of glass4 ,if now we take a drop of blood1 or of ,indian ink1 and drop it carefully into the middle of the salt solution1 we shall find that the coloured particles will travel along the lines of diffusive force1 and thus map out for us a monopolar field of diffusion1 as in ,fig4 #c a4 ,again1 if we place two similar drops side by side in a salt solution1 their lines of diffusion will repel one another1 as in ,fig4 #d4 ,illustration3 ,,fig4 #d4--,two drops of blood in a more concentrated solution1 showing a field of diffusion between two poles of the same sign4 ,now let us put into the solution1 side by side1 one drop of less concentration and another of greater concentration than the solution4 ,the lines of diffusion will pass from one drop to the other1 diverging from the centre of one drop and converging towards the centre of the other 7,fig4 #c b74 ,in this manner we are able to obtain diffusion fields analogous to the magnetic fields between poles of the same sign and poles of opposite signs4 ,the conception of poles of diffusion is of the greatest importance in biology1 throwing a flood of light on a number of phenomena1 such as karyokinesis1 which have hitherto been regarded as of a mysterious nature4 ,it also enables us to appreciate the role played by diffusion in many other biological phenomena4 ,consider1 for example1 a centre of anabolism in a living organism4 ,here the molecules of the living protoplasm are in process of construction1 simpler molecules being united and built up to form larger and more complex groups4 ,as a result of this aggregation the number of molecules in a given area is diminished1 i4e4 the concentration and the osmotic pressure fall1 producing a hypotonic centre of diffusion4 ,we may thus regard every centre of anabolism as a negative pole of diffusion4 #eh ,consider1 on the other hand1 a centre of catabolism1 where the molecules are being broken up into fragments or smaller groups4 ,the concentration of the solution is increased1 the osmotic pressure is raised1 and we have a hypertonic centre of diffusion4 ,every centre of catabolism is therefore a positive pole of diffusion4 ,similar considerations as to the formation and breaking up of the molecules in anabolism and catabolism apply to polymerization4 ,the diffusion field has similar properties to the magnetic and the electric field4 ,thus there is repulsion between poles of similar sign1 and attraction between poles of different signs4 ,a simple experiment will show this4 ,a field of diffusion is made by pouring on a horizontal glass plate a #aj per cent4 solution of gelatine to which #e per cent4 of salt has been added4 ,the gelatine being set1 we place side by side on its surface two drops1 one of water1 and one of a salt solution of greater concentration than #e per cent4 ,we have thus two poles of diffusion of contrary signs1 a hypotonic pole at the water drop1 and a hypertonic pole at the salt drop4 ,diffusion immediately begins to take place through the gelatine1 the drops become elongated1 advance towards one another1 touch1 and unite4 ,if1 on the contrary1 the two neighbouring drops are both more concentrated or both less concentrated than the medium1 they exhibit signs of repulsion as in ,fig4 #d4 ,diffusion not only sets up currents in the water and in the solutes1 but it also determines movements in any particles that may be in suspension1 such as blood corpuscles1 particles of ,indian ink1 and the like4 ,these particles are drawn along with the water stream which passes from the hypotonic centres or regions toward those which are hypertonic4 ,these considerations suggest a vast field of inquiry in biology1 pathology1 and therapeutics4 ,inflammation1 for example1 is characterized by tumefaction1 turgescence of the tissues1 and redness4 ,the essence of inflammation would appear to be destructive dis-assimilation with intense catabolism4 ,we have seen that a centre of catabolism is a hypertonic focus of diffusion4 ,hence the osmotic pressure in an inflamed region is increased1 turgescence is produced1 and #ei the current of water carries with it the blood globules which produce the redness4 ,the phenomenon of agglutination may also possibly be due to osmotic pressure1 a positive centre of diffusion attracting and agglomerating the particles held in suspension4 ,tactism and ,tropism4--,the phenomena of tactism and tropism may also be partly explained by the action of these diffusion currents of particles in suspension1 these polar attractions and repulsions4 ,in all experiments on this subject we should take into account the possible influence of osmotic pressure1 since many of the causes of tactism or tropism also modify the osmotic pressure at the point of action1 and it is possible that this modification is the true cause of the phenomenon4 ,osmotactism and osmotropism have not as yet been sufficiently studied4 ,illustration3 ,,fig4 #e4--,liquid figures of diffusion4 ,the six negative poles of diffusion are coloured with ,indian ink4 ,the positive pole in the centre is uncoloured and is formed by a drop of ,,kno#c solution4 ,thus it may be said that osmotic pressure dominates all the kinetic and dynamic phenomena of life1 all those at least which are not purely mechanical1 like the movements of respiration and circulation4 ,the study of these vital phenomena is greatly facilitated by the conception of the field of diffusion and poles of diffusion1 and of the lines of force1 which are the trajectories of the molecules of the solutes1 and the particles and globules in suspension4 ,the ,morphogenic ,effects of ,diffusion4--,many interesting experiments may be made showing variations of the lines of force in a field of diffusion1 and how liquids subjected only to differences of osmotic pressure diffuse and mix with one #fj another in definite patterns4 ,when a liquid diffuses in another undisturbed by the influence of gravity1 it produces figures of geometric regularity1 and we may thus obtain figures and forms of infinite variety4 ,the following is our method of procedure4 ,a glass plate is placed absolutely horizontal and is covered with a thin layer of water or of saline solution4 ,then with a pipette we introduce into the solution1 in a regular pattern1 a number of drops of liquid coloured with ,indian ink4 ,a wonderful variety of patterns and figures may be obtained by employing solutions of different concentration and varying the position of the drops4 ,illustration3 ,,fig4 #f4--,pattern produced in gelatine by the diffusion of drops of concentrated solutions of nitrate of silver and bromide of ammonium4 ,instead of the water or salt solution1 we may spread on the plate a #e or #aj per cent4 solution of gelatine1 containing various salts in solution4 ,if now we sow on this gelatine drops of various solutions which give colorations with the salts in the gelatine1 we may obtain forms of perfect regularity1 presenting most beautiful colours and contrasts4 ,the drops1 of course1 must be placed in a symmetrical pattern4 ,in this way we may obtain an endless number of ornamental figures4 ,in order to cover a lantern slide #h-a_/b cm4 x #aj cm41 about #e c4c4 of gelatine is required4 ,to this amount of gelatine we add a single drop of a saturated solution of salicylate of sodium1 and spread the liquid gelatine evenly over the plate4 ,when the gelatine has set1 we put the plate over a diagram1 a hexagon for instance1 and place a drop of ferrous sulphate solution at each of the six angles4 ,the drops immediately diffuse #fa through the gelatine1 and the result after a time is the production of a beautiful purple rosette4 ,the gelatine must be carefully covered to prevent its drying until the diffusion is complete4 ,the preparation may then be dried and mounted as a lantern slide1 and will give the most brilliant effect on projection4 ,if the gelatine has been treated with a drop of potassium ferrocyanide solution instead of salicylate of sodium1 a few drops of ,fe,s,o#d will give a blue pattern4 ,or we may treat the gelatine with ferrocyanide of potassium and salicylate of sodium mixed1 and thus obtain an intermediary colour on the addition of ,fe,s,o#d4 ,we may1 indeed1 vary indefinitely the nature and concentration of the solution1 as well as the number and position of the drops4 ,the results have all the charm of the unexpected1 which adds greatly to the interest of the experiment4 ,illustration3 ,,fig4 #g4--,pattern produced in gelatine by the diffusion of drops of silver nitrate and sodium carbonate4 ,these experiments are not merely a scientific toy4 ,they show us the possibility1 hitherto unsuspected1 that a vast number of the forms and colours of nature may be the result of diffusion4 ,thus many of the phenomena of life1 hitherto so mysterious1 present themselves to us as merely the consequences of the diffusion of one liquid into another4 ,one cannot help hoping that the study of diffusion will throw still further light on the subject4 ,if a number of spheres1 each capable of expansion and deformation1 are produced simultaneously in a liquid1 they will form polyhedra when they expand by growth4 ,this is the #fb precise architecture of a vast number of living organisms and tissues1 which are formed by the union of microscopic polyhedra or cells4 ,a section of such a polyhedral structure would appear as a tissue of polygons4 ,it is interesting to note that the simple process of diffusion will produce such structures under conditions closely allied to those which govern the development of the tissues of a living organism4 ,illustration3 ,,fig4 #h4--,pattern produced in gelatine by the diffusion of drops of a solution of nitrate of silver and of citrate of potassium4 ,we may obtain this cellular structure by a simple experiment4 ,on a glass plate we spread a #e per cent4 solution of pure gelatine1 and when set sow on it a number of drops of a #e to #aj per cent4 solution of ferrocyanide of potassium4 ,the drops must be placed at regular intervals of #e mm4 all over the plate4 ,when these have been allowed to diffuse and the gelatine has dried1 we obtain a preparation which exactly resembles the section of a vegetable cellular tissue 7,fig4 #i74 ,the drops have by mutual pressure formed polygons1 which appear in section as cells1 with a membranous envelope1 a #fc nucleus1 and a cytoplasm1 which is in many cases entirely separated from the membrane4 ,these cells when united form a veritable tissue1 in all respects similar to the cellular structure of a living organism4 ,illustration3 ,,fig4 #i4--,tissue of artificial cells formed by the diffusion in gelatine of drops of potassium ferrocyanide4 ,in the preparation showing artificial cells the cellular structure is not directly visible until the gelatine has dried4 ,one sees only a gelatinous mass analogous to the protoplasm of a living organism4 ,this mass is nevertheless organized1 or at least in process of organization1 as we may see by the refraction when its image is projected on the screen4 ,during the cell-formation1 and as long as there is any difference of concentration in the gelatine1 each cell is the arena of active molecular movement4 ,there is a double current1 as in the living cell1 a stream of water from the periphery to the centre1 and of the solute from the centre to the periphery4 ,this molecular activity--the life of the artificial cell--may be prolonged by appropriate nourishment1 #fd i4e4 by continually repairing the loss of concentration at the centre of the cell4 ,the life of the artificial cell may also be prolonged by maintaining around it an appropriate medium4 ,if we prematurely dry such a preparation of artificial cells1 the molecular currents will cease1 to recur again when we restore the necessary humidity to the preparation4 ,this to my mind gives us a most vivid picture of the conditions of latent life in seeds and many rotifera4 ,these artificial cells1 like living organisms1 have an evolutionary existence4 ,the first stage corresponds to the process of organization1 the gelatine representing the blastema1 and the drop the nucleus4 ,thus the cell becomes organized1 forming its own cytoplasm and its own enveloping membrane4 ,the second stage in the life of this artificial cell is the period during which the metabolism of the cell is active and tends to equalize the concentration of the liquid in the cell and in the surrounding medium4 ,the third stage is the period of decline4 ,the double molecular current gradually slows down as the difference of concentration decreases between the cell contents and its entourage4 ,when this equality of concentration has become complete the molecular currents cease1 the cell has terminated its existence2 it is dead4 ,the currents of substance and of energy have ceased to flow--the form only remains4 ,these artificial cells are sensible to most of the influences which affect living organisms4 ,like living cells they are influenced both in their organization and in their development by humidity1 dryness1 acidity1 or alkalinity4 ,they are also greatly affected by the addition of minute quantities of chemical substances either to the gelatinous blastema or to the drops which represent the primary nuclei4 ,we may in this way obtain endless varieties1 nuclei which are opaque or transparent1 with or without a nucleolus1 and cells containing homogeneous cytoplasm without a nucleus4 ,we may also obtain cells with cytoplasm filling the whole of the cellular cavity or separated from the cell-membrane4 ,we may obtain #fe cells imitating all the natural tissues1 cells without a membranous envelope1 cells with thick walls adhering to one another1 or cells with wide intracellular spaces4 ,illustration3 ,,fig4 #aj4--;,artificial liquid cells1 formed by coloured drops of concentrated salt solution in a less concentrated salt solution4 ,the forms of these artificial cells depend on the number and relative position of the drops which represent the nuclei1 and on the molecular concentration or osmotic tension of the solution4 ,the number of the cellular polyhedra is determined by the number of centres of diffusion4 ,the magnitude of the dihedral angles1 from which radiate three and occasionally four walls1 depends on the position of the hypertonic poles of diffusion4 ,the curvature of a surface is determined by the differences of concentration on either side4 ,between isotonic solutions the surface is plane1 whilst it is curved between solutions of different osmotic pressures1 the convexity being directed towards the hypertonic solution4 ,illustration3 ,,fig4 #aa4--,liquid cells with a fringe of cilia1 obtained by sowing coloured drops of concentrated salt solution in a weaker salt solution4 ,the contents of the cells have undergone segmentation4 ,the time required for these artificial cells to grow varies from two to twenty-four hours1 according to the concentration of the gelatine1 the growth being most rapid in dilute solutions4 ,similar cells may be produced in water4 ,if we pour a thin layer of water on a horizontal plate1 and with a pipette #ff sow in it a number of drops of salt water coloured with ,indian ink1 we may obtain artificial cells composed entirely of liquid1 having the same characters as those produced in a gelatinous solution4 ,it is possible by liquid diffusion to produce not only ordinary cells but ciliated cells4 ,if we spread a layer of salt water on a horizontal glass plate1 and sow in it drops of ,indian ink1 artificial cells are produced by diffusion4 ,at the edge of the preparation there is often to be seen a sort of fringe1 analogous to the cilia of living cells 7,fig4 #aa74 ,these tissues of artificial cells demonstrate the fact that inorganic matter is able to organize itself into forms and structures analogous to those of living organisms under the action of the simple physical forces of osmotic pressure and diffusion4 ,the structures thus produced have functions which are also analogous to those of living beings1 a double current of diffusion1 an evolutionary existence1 and a latent vitality when desiccated or congealed4 99 99 99 99 99 #fg ,,chapter ,,vi ,,periodicity ,periodic ,precipitation4--,a phenomenon is said to be periodic when it varies in time and space and is identically reproduced at equal intervals4 ,we are surrounded on all sides by periodic phenomena2 summer and winter1 day and night1 sleep and waking1 rhythm and rhyme1 flux and reflux1 the movements of respiration and the beating of the heart1 all are periodic4 ,our first sorrows were appeased by the periodic rhythm of the cradle1 and in our later years the periodic swing of the rocking-chair and the hammock still soothe the infirmities of old age4 ,sound is a periodic movement of the atmosphere which brings to us harmony and melody4 ,light consists of periodic undulations of the ether which convey to us the beauty of form and colour4 ,periodic ethereal waves waft to us the wireless message through terrestrial space and the radiant energy of the sun and stars4 ,it is therefore not to be wondered at that the phenomena of diffusion are also periodic4 ,according to ,professor ,quinke of ,heidelberg1 the first mention of the periodic formation of chemical precipitates must be attributed to ,runge in #ahhe4 ,since that time these precipitates have been studied by a number of authors1 and particularly by ,r4 ,liesegang of ,duesseldorf1 who in #aijg published a work on the subject1 entitled ,on ,stratification by ,diffusion4 ,in #aija ,i presented to the ,congress of ,ajaccio a number of preparations showing concentric rings1 alternately transparent and opaque1 obtained by diffusing a drop of potassium ferrocyanide solution in gelatine containing a trace of ferric #fh sulphate4 ,at the ,congress of ,rheims in #aijg ,i exhibited the result of some further experiments on the same subject4 ,these periodic precipitates may be obtained from a great number of different chemical substances4 ,the following is the best method of demonstrating the phenomenon4 ,a glass lantern slide is carefully cleaned and placed absolutely level4 ,we then take #e c4c4 of a #aj per cent4 solution of gelatine and add to it one drop of a concentrated solution of sodium arsenate4 ,this is poured over the glass plate whilst hot1 and as soon as it is quite set1 but before it can dry1 we allow a drop of silver nitrate solution containing a trace of nitric acid to fall on it from a pipette4 ,the drop slowly spreads in the gelatine1 and we thus obtain magnificent rings of periodic precipitates of arsenate of silver1 with which any one may easily repeat the experiments detailed in this chapter4 ,illustration3 ,,fig4 #ab4--,lines of diffusion precipitate1 showing the simultaneous propagation of undulations of different wave-length4 ,circular ,waves of ,precipitation4--,the wave-front of the periodic rings of precipitates is always perpendicular to the rays of diffusion4 ,the distance between the rings depends on the concentration of the diffusing solution4 ,the greater the fall of concentration1 the less is the interval between the rings4 ,each ring represents an equipotential line in the field of diffusion4 ,these equipotential lines of diffusion give us the best and most concrete reproduction of the mode of propagation of periodic waves in space4 ,they are1 in fact1 a visible diagram of the propagation of the waves of light and sound4 ,occasionally we may observe in the gelatine the simultaneous propagation of undulations of different wave-length1 just as we have them in the ether and the air4 ,these diffusion wavelets #fi give us a very beautiful representation of the simultaneous propagation of undulations of different wave-length in the same medium4 ,illustration3 ,,fig4 #ac4--,waves of diffusion refracted at a plane surface on passing from a less concentrated into a more concentrated solution4 ,the refracted wave-front is flattened1 the wave-length being less in the denser medium4 ,like waves of light and sound1 these waves of diffusion are refracted when they pass from one medium into another of a different density1 where they have a different velocity4 ,when1 for instance1 a diffusion wave passes from a #e per cent4 solution of gelatine into a #aj per cent4 solution1 the wave-front is retarded1 the retardation being proportional to the length of the path through the denser medium4 ,hence the wave-front is flattened1 the curvature of the refracted wave being less than that of the original wave of diffusion4 ,the contrary is the case when the wave-front passes into a medium where its velocity is greater4 ,the middle of the wave-front now travels faster than the flanks1 and the curvature is increased4 ,illustration3 ,,fig4 #ad4--,transformation of a spherical wave-front into a plane wave-front by a convergent diopter4 ,these diffusion rings furnish us with most excellent diagrams of refraction at a diopter1 i4e4 a spherical surface separating two media of different densities4 ,fig4 #ad shows the refraction at a convergent diopter1 i4e4 a surface where the denser medium is convex4 ,the diffusion waves in this case emanate from the principal focus of the diopter1 and therefore become plane on passing through the convex surface of the denser gelatine4 ,these periodic diffusion rings also illustrate the phenomena of colour diffraction4 ,diffusion waves of different #gj wavelength are unequally refracted by a gelatine lens4 ,hence rings of different wave-length which1 originating at the same spot1 are at first concentric1 are no longer parallel after passing through a gelatine lens4 ,a convergent lens which will change the long spherical incident waves into shorter plane waves1 will transform the short incident waves into concave waves whose curvature is opposite to that of the original waves1 i4e4 it will transform a divergent into a convergent beam4 ,this is an illustration of what is called the aberration of refrangibility4 ,in the same way we may demonstrate the course of diffusion waves through a gelatine prism1 showing the refraction on their incidence and again on emergence4 ,the prism is made of a stronger gelatine solution1 which is more refractive than the gelatine around it4 ,the waves of diffusion whilst traversing the prism are retarded1 and this retardation is greatest at the base where the passage is longer4 ,hence the wave-front is tilted towards the base of the prism1 and this tilting is repeated when the wave-front leaves the prism4 ,if we examine diffusion waves of different wave-length on their emergence from the gelatine prism1 we shall see that they cut one another4 ,with a dense prism1 the wave-front of the shorter waves is more tilted towards the base than the wave-front of the longer waves4 ,for diffusion as for light the shorter waves are the most refracted4 ,both refraction and dispersion are due to the unequal resistances of the medium to undulatory movements of different periodicity4 ,illustration3 ,,fig4 #ae4--;,diffraction of diffusion waves on passing through a narrow aperture4 ,diffraction4--,when light traverses a minute orifice1 instead #ga of passing on in a straight line1 it spreads out like a fan1 forming a diverging cone of light1 just as if the orifice were itself a luminous point4 ,this is the phenomenon of diffraction which has hitherto been considered incompatible with the emission theory of light4 ,diffusion waves may also be made to pass through a narrow orifice1 when they will behave exactly like the waves of light4 ,the new waves radiate from the orifice like a fan1 instead of giving a cone of waves bounded by lines passing through the circumference of the orifice and the original centre of radiation4 ,thus on passing through a small orifice diffusion waves exhibit the phenomenon of diffraction just as light waves do4 ,illustration3 ,,fig4 #af4--;,interference of diffusion waves4 ,interference4--,the phenomenon of interference may also be illustrated by waves of diffusion4 ,if on a gelatine plate we produce two series of diffusion waves from two separate centres1 we get at certain points an appearance corresponding to the interference of two sets of light waves4 ,this appearance is best shown by sowing on the gelatine film a straight row of drops equidistant from one another4 ,it should be remarked that this phenomenon of the production of circles of precipitate separated by transparent spaces1 although periodic1 is not of necessity vibratory or undulatory4 ,it would thus appear that periodic phenomena may be propagated through space without vibratory or oscillatory motion4 ,if we submit to a critical examination the various experiments which have established the undulatory theory of light1 we find that they do indeed demonstrate the periodic nature of light1 but in no wise prove that light is a vibratory movement of the ether4 #gb ,on the contrary1 the hypothesis that light is propagated by vibratory movements is open to many objections4 ,even the ,zeeman effect1 although it may tend to establish the fact that light is produced by vibratory movement1 by no means proves that it is propagated in the same manner4 ,when the theory was accepted that the transmission of light was periodic it was supposed that this periodic transmission could only be vibratory or undulatory in character1 since waves or vibrations were the only periodic phenomena known at that time4 ,we now know that there are other means of periodic transmission which are apparently not undulatory4 ,the periodic precipitates produced by diffusion show us the transmission of spherical waves through space1 which follow the laws of light1 although the periodic phenomenon is apparently emissive rather than vibratory4 ,it will be remembered that ,newton considered light to be produced by projectile-like particles emanating from a centre1 and proceeding in straight lines in all directions4 ,this emission theory of light was abandoned in favour of ,huygens' undulatory theory4 ,it was said that the phenomena of interference and diffraction could not be explained by the theory of emission1 while the undulatory theory gave a simple explanation4 ,the scientific mind was unable to conceive the idea of emission and periodicity as taking part in the same phenomenon4 ,the savants and thinkers who have meditated on this question have always considered the theory of emission and that of periodicity as incompatible4 ,nevertheless1 we are here in presence of a phenomenon in which emission and periodicity exist simultaneously4 ,the molecules emanating from our drop are diffused in straight radiating lines1 and yet produce periodic precipitates which are subject to interference and diffraction like the undulations of ,huygens4 ,the phenomena associated with the pressure of light1 the #gc discovery of the cathode rays and the radiations of radium1 together with the introduction of the electron theory of electricity1 all seem to have brought again into greater prominence ,newton's original conception of the emissionary nature of light4 ,some of the phenomena of radiation can be explained only by the emission theory1 and others by the undulatory theory of light4 ,all these difficulties would be solved if we admitted the hypothesis that radiating bodies project electrons1 which produce in the ether periodic waves similar to those formed in our gelatine films by the molecules of diffusion4 ,these diffusion films are of the greatest possible service in the practical teaching of optics4 ,they place before the eye of the student a working model as it were of the undulations of light4 ,when projected on the screen1 they give excellent pictures of the phenomena of refraction1 diffraction1 and interference1 and the simultaneous propagation of undulation of different wave-lengths1 and they show in a visible manner the changes of wave-length in media of different densities4 ,diffusion waves differ greatly in length1 varying from several millimetres to #b mu4 ,many are even shorter than this1 too short to be separately distinguished even under the highest power of the microscope1 when they give the effect of moire or mother-of-pearl4 ,it is easy to construct a spectroscopic grating in this way with fine lines whose distance apart is of the order of a micron1 separated by clear spaces4 ,every physical laboratory may thus produce its own spectroscopic gratings1 rectilinear1 circular1 or of any desired form4 ,the most beautiful colour effects may be produced with these diffusion gratings1 as we have shown at the ,congress of ,rheims in #aijg4 ,we have a considerable collection of these diffusion gratings1 some with very fine lines1 giving a very extended spectrum1 and others with coarser striations which give a large number of small spectra4 ,this study of periodic precipitates is of the highest interest when we come to investigate the production of colour in natural objects1 such as the wings of insects or the plumage of #gd birds4 ,many tissues have this lined or striated structure and exhibit interference colours like those of the periodic precipitates1 their structure showing alternate transparent and opaque lines1 whose width is of the order of a micron4 ,this is the structure of muscle1 and to this striated surface is also attributable many of the most beautiful colours of nature1 the gleam of tendon and aponeurosis1 the fire of scarab and beetle1 the colours of the peacock1 and the iridescence of the mollusc and the pearl4 ,the study of liquid diffusion has given us an idea of the physical mechanism by which these striated tissues are produced1 a mechanism which up to the present time has not been even suspected4 ,our experiments show how readily such striped or ruled structures may be produced in a colloidal solution by the simple diffusion of salts such as are found in every living organism4 ,illustration3 ,,fig4 #ag4--,photomicrograph of striated structure of a periodic precipitate of carbonate and phosphate of lime 7magnified #ejj times74 ,to make a spectroscopic grating by diffusion we proceed as follows4 ,we take #e c4c4 of a #aj per cent4 solution of gelatine1 and add to it one drop of a concentrated solution #ge of calcium nitrate4 ,we spread the gelatine evenly over a plain glass lantern slide and allow it to set4 ,after it is set1 but before it dries1 we place in the centre of the slide a drop of concentrated solution containing two parts of sodium carbonate 7,na#b;,,co#c7 to one of dibasic sodium phosphate 7,na#b;,,hpo#d74 ,tribasic sodium phosphate alone without the addition of the carbonate will also give good results4 ,if the phosphate solution is placed on the gelatine in the form of a drop1 we obtain circular periodic precipitates4 ,if it is desired to make a rectilineal grating1 we deposit the phosphate solution on the gelatine in a straight line by means of two parallel glass plates4 ,in this way we may obtain lines of periodic precipitation to the number of #ejj to #ajjj per millimetre1 forming gratings which produce most beautiful spectra4 ,pearls and mother-of-pearl both owe their iridescence to a similar ruled structure1 which is developed in the living tissue of a mollusc4 ,they are1 in fact1 periodic precipitates of phosphate and carbonate of lime deposited in the colloidal organic substance of the mollusc4 ,they have the same structure and the same chemical composition2 they have the same physical properties1 the glow1 the fire1 and the brilliancy of our spectroscopic gratings4 ,in these experiments1 indeed1 we have realized the synthesis of the pearl1 not only a chemical synthesis1 but the synthesis of its structure and organism4 ,we have been able to make these periodic precipitates by the reaction of a great number of chemical substances1 giving a bewildering variety of form and structure4 ,some of these recall the form of various organisms1 and especially of insects1 as may be seen in ,fig4 #ah4 ,all the phenomena of life are periodic4 ,the movement of heart and lungs1 sleep and waking1 all nervous phenomena1 have a regular periodicity4 ,it is possible that the study of these purely physical phenomena of periodic precipitation may give us the key to the causation of rhythm and periodicity in living beings4 ,besides this periodic precipitation there appear to be other chemical reactions which are periodic4 ,professor ,bredig of ,heidelberg has lately described a curious phenomenon1 the #gf periodic catalysis of peroxide of hydrogen by mercury4 ,he thus describes his experiment3 ,we place in a perfectly clean test tube a few cubic centimetres of perfectly pure mercury4 ,upon this we pour #aj c4c4 of a #aj per cent4 solution of hydrogen peroxide4 ,the mercury speedily becomes covered with a thin1 brilliant bronze-coloured pellicle which reflects light4 ,then little by little catalysis of the hydrogen peroxide begins1 with liberation of oxygen4 ,after some time1 from five to twenty minutes1 the liberation of gas at the surface of the mercury ceases1 the cloud formed by the gas bubbles disappears1 and the bronze mirror at the surface of the mercury lights up with the glint of silver4 ,there is a pause of one or more seconds1 and then the catalytic action begins afresh1 commencing at the edges of the mirror4 ,the cloud is again formed and again disappears4 ,this beautiful and surprising rhythmic phenomenon may continue at regular intervals for an hour or more4 ,illustration3 ,,fig4 #ah4--;,articulate form produced by periodic precipitation4 ,a slight alkalinity of the liquid is necessary to start the phenomenon4 ,this explains the retardation at the beginning #gg of the experiment1 since the rhythmic catalysis cannot begin until the hydrogen peroxide has dissolved a little of the glass so as to render it slightly alkaline4 ,the catalytic process may1 however1 be set going at once by adding a trace of potassium acetate to the solution4 ,we may even obtain a curve giving an automatic record of the periodicity of this catalytic action4 ,for this purpose the oxygen given off is led to a manometer1 which registers on a revolving drum the periodic variation in pressure4 ,the curve thus obtained presents a remarkable resemblance to a tracing of the pulse4 ,the frequency and character of the undulatory curve is modified by physical and chemical influences4 ,like circulation or respiration1 periodic catalysis has its poisons1 and exhibits signs of fatigue1 and of paralysis by cold4 ,the rhythmic catalysis of ,bredig produces an electrical current of action between the mercury and the water just like that produced by the rhythmic contraction of the heart1 and this current may be registered in a similar way by means of the ,einthoven galvanometer4 ,thus the heart-beat may be but an instance of rhythmic catalysis1 since both produce the same phenomena1 movement1 chemical action1 and periodic currents4 ,in the chapter on physiogenesis we shall return to the study of this question and consider another rhythmic phenomenon which is the result of osmotic growth4 99 99 99 99 99 #gh ,,chapter ,,vii ,,cohesion ,,and ,,crystallization ,chemical affinity is the force which holds together the different atoms in a molecule4 ,cohesion is the force which holds together molecules which are chemically similar4 ,although physical science distinguishes three states of matter1 solid1 liquid1 and gaseous1 yet here as elsewhere there are no sharp dividing lines1 but rather an absolute continuity4 ,we have in fact many intermediate states2 between liquids and gases there are the various conditions of vapour1 and between liquids and solids we get viscous1 gelatinous1 and paste-like conditions4 ,the only real difference between solids1 liquids1 and gases is the intensity of the force of cohesion1 which is considerable in solids1 feeble in liquids1 and absent in gases4 ,a living organism is the arena in which are brought into play the opposing forces of cohesion and disintegration4 ,the study of cohesion is therefore a vital one for the biologist1 and especially cohesion under the conditions which obtain in living beings1 viz4 in liquids of heterogeneous constitution4 ,the forces of cohesion brought into play under these conditions may be beautifully illustrated by a simple experiment4 ,we take a plate of glass1 well cleaned and absolutely horizontal4 ,on it we pour a layer of salt water1 and in the middle we carefully drop a spot of ,indian ink4 ,the drop at once begins to diffuse1 and we obtain a circular figure1 like the monopolar field of diffusion already described1 the rays of diffusion radiating from the centre in all directions4 ,illustration3 ,,fig4 #ai4--,muriform cohesion figure formed by a drop of ,indian ink in a solution of salt4 ,if we keep the plate carefully protected from all disturbing influences1 after some ten to twenty minutes we shall see the coloured particles returning on their path1 and the centre of #gi the drop becoming more and more black4 ,each line of force becomes segmented into granules1 which gradually increase in size1 and approach nearer to one another and to the centre of the drop1 until it assumes the mulberry appearance shown in the photograph 7,fig4 #ai74 ,illustration3 ,,fig4 #bj4--,seven similar drops of ,indian ink diffusing in a salt solution4 ,two minutes after introducing the drops4 ,if we sow a number of drops of ,indian ink in regular order on the surface of a salt solution1 we obtain most beautiful patterns formed by the mutual repulsion of the drops4 ,figs4 #bj1 #ba1 and #bb represent the successive aspects of seven drops of ,indian ink thus sown on a layer of salt solution1 and kept undisturbed long enough to allow of their evolution4 ,fig4 #bj shows the aspect after two minutes1 when the diffusion is almost complete4 ,in ,fig4 #ba1 photographed after fifteen #hj minutes1 the colouring matter has almost entirely reunited to form separate granulations2 whilst in ,fig4 #bb1 taken after thirty minutes1 these granulations are rearranged to form an agglomeration around the centre of each drop4 ,illustration3 ,,fig4 #ba4--,the same drops #ae minutes later1 showing the granulation appearance4 ,the following experiment1 which is more difficult1 will show the cohesive attraction of one drop for another4 ,a plate of glass is adjusted absolutely horizontal1 and covered as before with a layer of salt solution4 ,on this we sow a number of drops of the same salt solution coloured with ,indian ink4 ,the drops must be of exactly the same concentration as the salt medium1 so as to avoid any difference of osmotic pressure between the drops and the medium1 otherwise the drops would not remain intact but would diffuse into the solution4 ,since under these conditions the liquid of the medium around the drops is perfectly symmetrical and homogeneous1 it cannot exercise any influence on the liquid of the drops4 ,illustration3 ,,fig4 #bb4--,the same drops after #cj minutes4 ,the granulations have agglomerated at the centre of the drops4 ,it is otherwise1 however1 with the colouring matter of the #ha drops4 ,the particles of ,indian ink may be seen passing from one drop to another1 the coloured circles become elongated towards one another1 touch1 and finally unite4 ,if1 as in ,fig4 #bc1 the drops are of different size1 the larger one will have a preponderating attractive action and eat up the smaller drops4 ,in the figure1 six small drops are placed around a large one1 and the smaller drops have begun to be deformed and to move towards the larger drop4 ,this central drop is also deformed1 and has assumed a more or less hexagonal form1 under the influence of the attraction of the six smaller ones4 ,it may be noticed that the least prominent angle of the hexagon is opposite the small drop which is farthest away from it1 whilst one of the smaller drops has already begun to be swallowed up by the large one4 ,this cohesion phenomenon is very slow in its action1 but after an hour or two the central drop will be found to have #hb completely absorbed the six smaller ones1 and only one large drop will remain4 ,illustration3 ,,fig4 #bc4--;,attraction between coloured drops in an isotonic solution4 ,incubation4--,in the living organism we frequently find conditions similar to those realized in this experiment1 viz4 very slow movements of diffusion in liquids containing particles in suspension4 ,in such cases the consequences must be the same1 viz4 granulation and segmentation4 ,consider for a moment the incubation of an egg4 ,the heat of incubation determines a certain amount of evaporation through the shell1 with a concentration of the liquid near the surface4 ,as a consequence of this superficial concentration we get segmentation of the vitellus1 with the production of a morula4 ,artificial ,parthenogenesis4--,the experimental parthenogenesis of ,loeb and ,delage consists in plunging the egg into a liquid other than sea water1 and returning it again to its original medium4 ,this operation will necessarily determine slow movements of diffusion in the egg1 which will give rise to segmentation4 ,it may be objected that segmentation is also produced by a solution which is isotonic with sea water4 ,such a solution would not indeed produce an exchange of water with the egg1 but it would set up an exchange of electrolytes1 since there would be a difference of their osmotic pressure in the egg and in the new isotonic medium4 ,the extremely slow movements of diffusion thus produced would be very favourable to the action of the cohesive force on the particles in suspension1 and hence to the segmentation of the egg4 ,illustration3 ,,fig4 #bd4--;,a circle of eight drops of ,indian ink #cj minutes after they have been sown in a salt solution4 ,the drops have undergone diffusion and subsequent cohesion1 resulting in a reticulate structure4 ,few physical phenomena give us a deeper insight into the phenomena of life than those which we here contemplate4 ,there is still another experiment which is even more convincing4 ,on the surface of our horizontal salt solution we sow a number of drops of a more concentrated salt solution at equal distances around the circumference of a circle4 ,movements of diffusion are thus set up in the interior of the circle1 and after a time1 when this diffusion has become so slow as to be almost imperceptible1 a furrow begins to appear in the coloured mass4 ,then a second and third appear1 and others crossing the former break up the mass #hc into segments4 ,finally the segmentation becomes complete1 and the preparation presents a muriform appearance1 looking in fact something like a mulberry 7,fig4 #bd74 ,if the preparation is preserved for several hours longer1 we may see the cells formed by segmentation unite around the circumference so as to form a hollow bag corresponding to a gastrula1 as shown in ,fig4 #be4 ,illustration3 ,,fig4 #be4--,the same preparation several hours later1 showing a cellular gastrula-like structure4 ,these preparations are extremely sensitive to external influences1 which renders the demonstration of cohesion phenomena difficult4 ,i have nevertheless on several occasions been able to project the experiment on the screen during a lecture4 ,the segmentation is influenced by very slight currents of diffusion1 and ,i have many preparations showing the segmentation regularly distributed in various ways along radial diffusion lines4 ,we may in this way produce many varieties of structure lamellar1 vacuolate1 or cellular1 in fact #hd all the tissue structures which are met with in living organisms4 ,all these structures are retractile1 the retraction going on very slowly for a long time1 as if the force of cohesion continued to act in the web of the structure even after its formation was complete4 ,the phenomenon is a purely physical synthetic reproduction of the phenomenon of coagulation1 the cohesion figure being in fact a retractile clot4 ,illustration3 ,,fig4 #bf4--;,field of crystallization of sodium chloride 7magnified #fj diameters74 ,crystallization4--,when we evaporate a solution of a crystalloid it becomes more concentrated1 slow movements of diffusion are set up1 and at a given moment agglomeration occurs1 the agglomerates taking the form of crystals4 ,thus crystallization may be regarded as a particular case of conglomeration by cohesion1 differing only in the regularity of the arrangement of the molecules1 which gives the geometrical form of the crystal4 ,hence we can easily understand how the presence of a crystalline fragment may facilitate the process of crystallization4 ,consider a liquid in which extremely slow movements of diffusion are taking place4 ,if the liquid is perfectly homogeneous there will be no centre of attraction to which the molecules may become attached4 #he ,illustration3 ,,fig4 #bg4--;,field of crystallization around a crystal of sodium chloride in process of formation4 ,if1 however1 a crystal or other heterogeneous structure is present1 it forms a centre of cohesion which will attach any molecules that are brought by diffusion into its sphere of attraction4 ,we have succeeded in photographing the arrangement of the molecules of a liquid around a crystal in the act of formation 7,fig4 #bf74 ,for this purpose we add to the solution traces of some colloidal substance1 such as gelatine or gum1 so as to delay the crystallization4 ,it may thus be shown that the molecules of the surrounding liquid are already arranged in crystalline order for some distance from the crystal1 forming a sort of field of crystallization4 ,the arrangement of this regular field varies in different cases1 and is more or less complicated according to circumstances4 ,one of the most frequent forms is that shown in ,fig4 #bg1 which is the field around a crystal of sodium chloride4 ,in the centre #hf of the crystal is a square with well-marked outline4 ,at each corner of this square there is a straight line at right angles to the diagonal1 which will form the sides of the crystal in process of formation4 ,from the middle of each side arise yet other perpendiculars1 which in their turn bear other cross lines1 each new line being set at right angles to its predecessor4 ,a later stage of crystallization is shown in ,fig4 #bg1 where the two squares one inside the other at an angle of #de;deg are clearly indicated4 ,illustration3 ,,fig4 #bh4--,three crystals of sodium chloride in process of formation1 each in the centre of a field of crystallization4 ,every crystallizable substance gives a different characteristic field of crystallization4 ,in #aijc1 at the ,congress of ,angers1 ,i terminated my address by these words3 ,the field of crystallization may serve to determine the character of a substance in solution4 ,i have subsequently received from ,carbonell y ,soles of ,barcelona an interesting work on this subject1 which he contributed to the ,international ,congress of ,medicine at ,madrid in #aijc1 entitled ,applicacion de la crystalogenia experimental a la investigacion toxicologica de cas alcaloides4 #hg ,six years ago ,i received from ,australia an exceedingly beautiful photograph of a thin pellicle found in a rain gauge4 ,my correspondent supposed that this strange figure might have been produced under the influence of an electric or magnetic field4 ,i was able to assure him by return of post that the figure was the result of the crystallization of copper sulphate in a colloidal medium4 ,in return ,i received a letter verifying this fact1 and saying that there were copper works in the neighbourhood1 and the air was filled with the dust of copper sulphate4 ,living beings are but solutions of colloids and crystalloids1 and their tissues are built up by the aggregation of these solutes4 ,we have already seen how the forces of crystallization are modified in colloid solutions4 ,this force of crystallization must play an important role in the metamorphoses of the living organism1 and influence their morphology4 ,it may therefore be of interest to investigate some of the numberless forms of crystallization in colloidal solutions4 ,illustration3 ,,fig4 #bi4--;,crystallization of sodium chloride in a colloidal solution1 giving a plant-like form4 ,illustration3 ,,fig4 #cj4--;,form produced by the crystallization of chloride of ammonium in a colloidal solution4 ,figs4 #bi and #cj represent the forms produced by chloride of sodium and chloride of ammonium respectively1 in solutions of gelatine of different degrees of concentration4 ,their resemblance to vegetable growth is so remarkable that several observers on first seeing them have called them ,fern-crystals4 ,i should like here to recall to your notice the work of an ,english observer1 ,dr4 ,e4 ,montgomery of ,st4 ,thomas's #hh ,hospital1 which was published as long ago as #ahfe4 ,this work was recently brought to my notice by the kindness of ,professor ,baumler of ,freiburg4 ,he says3 ,crystals are not strangers in the organic world4 ,many organic compounds are able to assume crystalline forms under certain conditions4 ,rainey has shown that many shells consist of globular crystals i4e4 of mineral substances made to crystallize by the influence of viscid material4 ,in this connection ,i may also mention the interesting work of ,otto ,lehmann of ,karlsruhe on liquid crystals4 ,in conclusion1 we may recall the words of ,schwann himself1 the originator of the cell theory3 ,the formation of the elementary shapes of an organism is but a crystallization of substances capable of imbibition4 ,the organism is but an aggregate of such imbibing crystals4 99 99 99 99 99 #hi ,,chapter ,,viii ,,karyokinesis ,in #ahgc1 ,hermann ,fol1 writing of the eggs of ,geryonia1 thus describes the phenomenon of karyokinesis3 ,on either side of the residue of the nucleus there appears a concentration of plasma1 thus forming two perfectly regular star-like figures1 whose rays are straight lines of granulations4 ,there are other curved rays which pass from one star or centre of attraction to the other4 ,the whole figure is extraordinarily distinct1 recalling in a striking manner the arrangement of iron filings surrounding the poles of a magnet4 ,sachs' theory is that the division of the nucleus is caused by centres of attraction1 and ,i agree with him1 not on theoretical grounds1 but because ,i have actually seen these centres of attraction4 ,since the discovery of ,hermann ,fol1 a great number of explanations have been given1 all of them theoretical1 to account for the figures and phenomena of karyokinesis4 ,many of these so-called explanations are mechanical1 while others invoke the aid of magnetism or electricity to account for the resemblance of the figures of karyokinesis to the magnetic or electric phantom or spectre4 ,among the authors who have dealt with this question we may mention ,hartog of ,cork1 ,gallardo of ,buenos ,ayres1 and ,rhumbler of ,goettingen4 ,in #aijd ,i presented to the ,grenoble ,congress1 and in #aijf to the ,lyons ,congress1 a series of photographs and preparations of experimental karyokinesis4 ,i showed how1 in a solution analogous to that found in the natural cell1 the simple processes of liquid diffusion1 without the intervention of magnetism or electricity1 may reproduce with perfect accuracy and in their normal sequence the whole of the movements and #ij figures which characterize the phenomenon of karyokinesis4 ,this experiment consists not merely in the production of a certain figure1 such as is obtained in the magnetic spectre1 but in the reproduction of the movement itself1 and of all the successive forms which are seen in the natural phenomenon4 ,these are evolved before the eyes of the spectator in their regular order and sequence4 ,i may here reproduce the text of my communication at ,grenoble3 ,until ,i introduced the conception of a field of diffusion1 there was no proper means of studying the phenomena of diffusion1 which obey the laws of a field of force as expounded by ,faraday4 ,moreover1 no one suspected the possibility of reproducing by liquid diffusion a spectre analogous to the electro-magnetic phantom4 ,guided by this theory of a diffusion field of force1 ,i have been able to reproduce experimentally the figures of karyokinesis by simple diffusion4 ,with regard to the achromatin spindle1 ,professor ,hartog has shown that the two poles of the spindle are of the same sign1 and not of opposite signs as was at first supposed4 ,in the process of karyokinesis the two centrosomes1 i4e4 the two poles of the achromatin spindle1 repel one another4 ,they must therefore be poles of the same sign4 ,an electric or magnetic spectre showing a spindle between two poles of the same sign is unknown2 such a thing would appear to be an absolute impossibility4 ,what is impossible in electricity and magnetism1 however1 is quite possible in the artificial diffusion field2 we can here have a spindle between two poles which repel one another--that is1 between poles of the same sign4 ,fig4 #ca is a photograph of such a spindle produced by diffusion4 ,on either side are two poles of concentration1 which represent the centrosomes1 each pole being surrounded by a star-like radiation4 ,these poles being alike1 repel one another4 ,in the preparation one may see the distance between the two poles slowly increase1 the poles gradually separating from one another just as do the centrosomes of an ovum during karyokinesis4 ,this preparation1 then1 which is produced entirely by diffusion1 presents a perfect resemblance to the achromatin spindle in karyokinesis4 #ia ,illustration3 ,,fig4 #ca4--;,diffusion figure representing karyokinesis4 ,achromatin spindle between two similar poles of concentration4 ,the spindle of which we give a photograph in ,fig4 #ca was made by placing in salt water a drop of the same solution pigmented with blood or ,indian ink1 and placing on either side of this central drop a hypertonic drop of salt solution more lightly coloured4 ,after diffusion had gone on for some minutes1 we obtained the figure which we have photographed4 ,i would draw your attention to the equatorial plane1 which shows that the spindle is not formed by lines of force passing from one pole to the other1 as would be the case between two poles of contrary sign1 but by two forces acting in opposite directions4 ,on either side the pigment of the central drop has been drawn towards the hypertonic centre nearest to it4 ,in the median line1 however1 the pigment is attracted in opposite directions by equal forces1 and therefore remains undisturbed1 marking the position of the equatorial plane4 ,this observation applies equally to the equatorial plane in natural karyokinesis1 whose existence is thus readily explained4 ,it is hardly necessary to insist on the fact that liquid preparations like these are of extreme delicacy and sensitiveness1 and require for their production1 and still more for their photography1 the greatest care and skill1 which can only be acquired by long practice4 #ib ,we are able to produce by diffusion not only the achromatin spindle1 but also the segmentation of the chromatin1 and the division of the nucleus4 ,if in the saline solution we place a coloured isotonic drop between two coloured hypertonic drops1 all the figures and movements of karyokinesis appear successively in their due order4 ,the central drop1 representing the nucleus between the two lateral drops or centrosomes1 first becomes granular4 ,next we see what appears to be a rolled-up ribbon analogous to the chromatin band1 which soon breaks into fragments analogous to the chromosomes4 ,these arrange themselves around1 and are gradually attracted towards the centrosomes1 where they accumulate to form two pigmented nuclear masses4 ,a partition then makes its appearance in the median line1 and this partition becomes continuous with the boundary of the spheres around the centrosomes4 ,finally we have two cells in juxtaposition1 each with its nucleus1 its protoplasm1 and its enveloping membrane4 ,i have been able to photograph these successive stages of the segmentation of the chromatin just as ,i have those of the achromatin spindle 7,fig4 #cb74 ,illustration3 ,,fig4 #cb4--;,four successive stages in the production of artificial karyokinesis by diffusion4 ,this memoir1 written in #aijd1 clearly asserts the homopolarity of the centrosomes1 and shows that the nuclear division is the result of a bipolar action1 two poles of the same sign exerting their influence on opposite sides of the nucleus4 ,it also emphasizes the important fact that diffusion1 #ic and as far as we know diffusion alone1 is able to produce a spindle between homologous poles4 ,a glance at the photograph is enough to show that the spindle is formed between poles of the same sign4 ,the lines of diffusion radiate from one centre and converge towards the other centre in curves1 giving the double convergence characteristic of a spindle4 ,the central drop merely supplies the necessary material1 and should have a concentration but slightly less than that of the plasma1 so as not to set up its own lines of diffusion4 ,the photograph shows clearly that the rays of the spindle traverse the equator without any break4 ,it has been objected that these lines form not so much a spindle as two hemi-spindles1 but it is clear that these two hemi-spindles are continuous and form a single sheaf of rays uniting the two poles of concentration4 ,this is a phenomenon entirely unknown in the magnetic or electric fields1 where two poles of the same sign1 one on either side of a pole of the contrary sign1 give two separate spindles4 ,in a magnetic field it is impossible to make the lines emanating from one pole converge1 except to a pole of opposite sign4 ,hence if we admit the homopolarity of the centrosomes1 we must also admit that diffusion is the vera causa of karyokinesis1 since1 as ,i showed at the ,grenoble ,congress in #aijd1 diffusion and diffusion alone is capable of producing a spindle between two poles of the same sign4 ,nuclear ,division4--,in order to reproduce artificially the phenomena attending the division of the nucleus1 we may proceed as follows4 ,we cover a perfectly horizontal glass plate with a semi-saturated solution of potassium nitrate to represent the cytoplasm of the cell4 ,the nucleus in the centre is reproduced by a drop of the same solution coloured by a trace of ,indian ink1 the solid particles of which will represent the chromatin granules of the nucleus4 ,the addition of the ,indian ink will have slightly lowered the concentration of the central drop1 and this is in accordance with nature1 since the osmotic pressure of the nucleus is somewhat less than that of the plasma4 ,we next place on either side of the drop which represents the #id nucleus a coloured drop of solution more concentrated than the cytoplasm solution4 ,the particles of ,indian ink in the central drop arrange themselves in a long coloured ribbon1 apparently rolled up in a coil1 the edges of the ribbon having a beaded appearance4 ,after a short time the ribbon loses its beaded appearance and becomes smooth1 with a double outline1 as is shown in ,a1 ,fig4 #cb4 ,this coil or skein of ribbon subsequently divides1 forming a nuclear spindle1 while the chromatin substance collects together in the equatorial plane as in ,b1 ,fig4 #cb4 ,a more advanced stage of the nuclear division is shown at ,c1 ,fig4 #cb1 where the chromatin bands of artificial chromosomes are grouped in two conical sheafs converging towards the two centrosomes4 ,for some considerable time these conical bundles remain united by fine filaments1 the last vestiges of the nuclear spindle4 ,the final stage is that of two artificial cells in juxtaposition1 whose nuclei are formed by the original centrosomes augmented by the chromatin bands or chromosomes 7,fig4 #cb1 ,d74 ,illustration3 ,,fig4 #cc4--;,equatorial crown produced by diffusion4 ,the resemblance of these successive phenomena to those of natural karyokinesis is of the closest4 ,the experiment shows that diffusion is quite sufficient to produce organic karyokinesis1 and that the only physical force required is that of osmotic pressure4 ,if in the cytoplasm of a cell there are two points of molecular concentration greater than that of the general mass1 the nucleus must necessarily divide with all the phenomena which accompany karyokinesis4 ,in nature these two centres of positive concentration are introduced into the protoplasm of the cell by fecundation--that is1 by the entrance of the centrosomes of the sperm cell4 ,in certain abnormal cases the concentration may be produced in the cell itself by the formation of two centres of catabolism or molecular disintegration1 since1 as we have seen1 molecular disintegration raises the osmotic pressure4 ,this phenomenon1 namely the production of karyokinesis from centres of catabolism1 may account for the abnormal karyokinesis of cancer cells and the like4 ,the subject is one which would well repay further investigation4 #ie ,illustration3 ,,fig4 #cd4--;,a triaster produced by diffusion4 ,it has been found in our experiments that in order to obtain the regular division of the artificial nucleus represented by the intermediary drop1 the latter must have an osmotic pressure slightly below that of the plasma4 ,this leads to the supposition that a similar condition must obtain in the natural cell4 ,it may be noticed1 moreover1 that the grains of pigment follow the direction of the flow of water1 being carried along by the stream4 ,this would appear to show that the nucleus of a natural cell has also a molecular concentration less than that of the plasma--a result either of dehydration of the plasma1 or of some diminution in the molecular concentration of the nucleus4 ,other phenomena of karyokinesis may also be closely imitated by diffusion4 ,for instance1 in the diffusion preparation we notice at each extremity of the equator a ,v-shaped figure with its apex towards the centre1 corresponding exactly to what in natural karyokinesis is called the equatorial crown4 ,we may also produce diffusion figures of abnormal karyokinesis4 ,fig4 #cd represents such a form1 a triaster produced by diffusion4 ,artificial karyokinesis may also be produced by hypotonic poles of concentration--that is to say1 when the central drop representing the ovum is positive and the lateral drops representing the centrosomes are negative with respect to the plasma4 ,in this case1 however1 the resemblance to natural karyokinesis is less perfect4 #if ,without attaching to it an importance which is not warranted by experimental results1 it is interesting to note that we have here two methods of fertilization1 hypertonic and hypotonic1 i4e4 by centrosomes of greater concentration and by centrosomes of less concentration than that of the plasma of the ovum1 and that we have in nature two corresponding results1 viz4 two different sexes4 ,it is possible that we have in these two methods of producing nuclear division the secret of the difference of sex4 99 99 99 99 99 #ig ,,chapter ,,ix ,,energetics ,movement is everywhere2 there is no such thing as immobility2 the very idea of rest is itself an illusion4 ,immobility is only apparent and relative1 and disappears under closer examination4 ,all terrestrial objects are driven with prodigious velocity around the sun1 and the dwellers on the earth's equator travel each day around the #dj1jjj kilometres of its circumference4 ,all objects on the globe are in motion1 the inanimate as well as the living4 ,the waters rise in vapour from the sea1 float over mountain and valley1 and return down the rivers to the sea again4 ,still more marvellous is the current of water which flows eternally from dew and rain1 through the sap of plants and the blood of animals to the mineral world again4 ,the very mountains crumble and their substance is washed down into the plains2 the winds move the air and raise the waves of the sea1 whilst the strong ocean currents are produced by variations of temperature in different parts4 ,this agitation1 this incessant and universal motion1 has been a favourite subject of poetic contemplation4 ,heraclitus writes3 ,there is a perpetual flow1 all is one universal current2 nothing remains as it was1 change alone is eternal4 ,ovid writes in his ,metamorphoses3 ,believe me1 nothing perishes in this vast universe1 but all varies1 and changes its figure4 ,i think that nothing endures long under the same appearance4 ,what was solid earth has become sea1 and solid ground has issued from the bosom of the waters4 ,the ,french poetess ,mme4 ,ackermann has expressed the same idea in beautiful verse3-- ,ainsi1 jamais d'arret4 ,l'immortelle matiere1 ,un seul instant encore n'a pu se reposer4 ,la ,nature ne fait1 patiente ouvriere1 ,que defaire et recomposer4 #ih ,tout se metamorphose entre ses mains actives2 ,partout le mouvement incessant et divers1 ,dans le cercle eternel des formes fugitives1 ,agitant l'immense univers4 ,it was only towards the middle of last century that mankind in the long search after unity in nature began to realize that all the movements of the universe are the manifestations of a single agent1 which we call energy4 ,in reality all the phenomena of nature may be conceived as diverse forms of motion1 and the word energy is the common expression applied to all the various modes of motion in the universe4 ,it was by the study of heat1 and more especially of thermodynamics1 that we obtained our conceptions of the science of energetics4 ,it was in ,munich in #agih that the ,english engineer ,count ,rumford first observed that in the operation of boring a cannon the copper was heated to such a degree that the shavings became red-hot4 ,this suggested his famous experiment1 in which a heavy iron pestle was turned by horse power in a metal mortar filled with water4 ,the water boiled1 and when more water was added this also became heated to ebullition1 and so on indefinitely4 ,rumford argued that the heat thus obtained in an indefinite quantity could not be a material substance2 that motion was the only thing added to the water without limit1 and that therefore heat must be motion4 ,while ,rumford's experiment showed the transformation of motion into heat1 the steam engine was soon afterwards to demonstrate the opposite transformation1 viz4 that of heat into motion4 ,the actual state of our knowledge with regard to the science of energy rests on two principles1 that of ,mayer and that of ,carnot4 ,the first principle was defined by ,j4 ,r4 ,mayer1 a medical practitioner of ,heilbronn1 whose work1 ,bemerkungen ueber die ,kraefte der unbelebten ,natur1 was published in #ahdb4 ,all physical phenomena1 says ,mayer1 whether vital or chemical1 are forms of motion4 ,all these forms of motion are susceptible of change into one another1 and in all the transformations the #ii quantity of mechanical work represented by different modes of motion remains invariable4 ,the energy of a given body is the amount of transferable motion stored up in that body1 and is measured by its capacity of producing mechanical work4 ,ostwald thus defines energy3 ,energy is work1 all that can be obtained from work1 and all that can be changed into work4 ,different forms of energy may be measured in different ways1 but all forms of energy can be measured either in units of mechanical work or in units of heat1 in kilogramme-metres or foot-pounds or in calories1 according as the energy in question is transformed into mechanical work or into heat4 ,the first principle of energetics1 the conservation of energy1 may be thus expressed3 ,energy is eternal2 none is ever created1 and none is ever lost4 ,the quantity of energy in the universe is invariable1 and is conserved for ever in its integrity4 ,the unit by which we measure quantities of heat is the calory1 the amount of heat required to raise the temperature of one kilogramme of water one degree ,centigrade4 ,the practical unit of mechanical work is the kilogramme-metre1 the work required to raise the weight of one kilogramme to the height of one metre4 ,the theoretical unit of work is one erg1 the work required to move a mass of one gramme through one centimetre against a force of one dyne4 ,joule of ,manchester was the first to verify ,mayer's law quantitatively4 ,by an experiment analogous to that of ,rumford1 he transformed work into heat1 arranging his apparatus so that he might measure the amount of heat produced and the work expended4 ,on dividing the quantity of work that had disappeared by the quantity of heat which had been disengaged1 he found that #dbd kilogramme-metres of work had been expended for each calory of heat produced4 ,hirn of ,colmar measured the ratio of work to heat in the steam engine4 ,he found that for each calory of heat which had disappeared there were produced #dbe kilogramme-metres of work4 #ajj ,this number #dbe has therefore been accepted as representing in calories and kilogramme-metres the transformation of work into heat1 and of heat into work4 ,further measurements on the transformations of other forms of energy1 chemical energy and electrical energy1 have shown that ,joule's law of equivalents is general1 and that the quantity of mechanical work represented by any form of energy remains undiminished after transformation1 whatever the nature of that transformation4 ,energy presents itself to us under two forms1 potential and actual4 ,potential energy is slumbering energy1 energy localized or locked up in the body4 ,in order to transform potential energy into actual energy1 there is required the intervention of an additional awakening1 stimulating1 or exciting energy from without4 ,this stimulating energy may be almost infinitesimal in amount and bears no quantitative relation to the amount of energy transformed4 ,it is the small amount of work required to turn the key which liberates an indeterminate quantity of potential energy4 ,actual energy1 on the other hand1 is energy in movement1 awake and alert1 ready to be transformed into any other form of energy without the intervention of any such external stimulating force4 ,the passage of a given quantity of energy from the potential into the actual state is effected gradually1 and during the time of transformation the sum of the actual and the potential energy remains constant4 ,a weight suspended by a cord possesses a quantity of potential energy equal to the product of its weight into the height through which it can fall4 ,this energy is locked up in a certain space1 it cannot be transformed without the intervention of some external energy to cut the cord4 ,during the falling of the weight1 at the middle of its path1 half of this slumbering energy has become kinetic1 and is represented by the vis viva of the weight1 while the other half is still potential and is equivalent to the work which the weight will accomplish during the second half of its fall4 ,at any moment the sum of these two energies1 the sleeping and the waking #aja energies1 represents the total potential energy of the weight before it began to fall4 ,so with the powder in a gun4 ,the potential energy of the powder cannot become actual without some stimulus1 some exciting force from without to set it free4 ,it is the external work of pressing the trigger that liberates the potential energy of the powder1 transforming it into the actual energy of combustion1 and the kinetic energy of the projectile4 ,since energy is work1 and work is a function of motion1 there is in reality no such thing as energy in repose4 ,matter according to our modern conception is a complex of molecules1 atoms1 and electrons2 we conceive the molecules of matter as always in movement1 animated with cyclic or vibratory motion1 these oscillatory or rotatory movements representing the potential energy of the body in question4 ,potential energy is thus the expression of molecular motion without translation of the molecules as a whole in space4 ,when this potential energy is transformed into actual energy by the intervention of some external force1 we get a current of energy1 a transference of the molecules in space4 ,thus1 when an external force has released the weight1 the molecular orbits in the falling body change in form1 and the potential energy of the molecular motion becomes the kinetic energy of the falling body4 ,similarly in the conduction of heat1 the energy of the hot body is transferred to a colder body by transmission of the vibratory motion from molecule to molecule4 ,so again with chemical energy1 the molecular motion of combustion may be transformed into the radiant energy of the ethereal waves4 ,actual energy may be regarded as a current of molecular motion4 ,to make the matter clearer1 let a mass of matter be represented by a regiment of soldiers4 ,then each soldier will represent an electron1 a company will be an atom1 and a battalion will be a molecule4 ,as long as the soldiers mark time1 turn1 or otherwise exercise without advancing1 we have simply an accumulation of potential energy4 ,the word of command1 ,march1 is the exciting force which suddenly transforms this potential into kinetic energy4 ,the marching #ajb regiment is a representation of a body possessing kinetic energy4 ,potential energy is energy confined to a certain point in space1 whereas actual energy is a current of energy1 continually changing its place or form4 ,energy is like water-power--potential in the lake1 actual in the waterfall or river4 ,any mechanism capable of causing one form of energy to pass into another is a transformer of energy4 ,a steam engine is a transformer of energy1 changing caloric energy into mechanical work4 ,an electrical machine is a transformer of energy1 converting mechanical motion into a current of electricity1 whilst an electro-motor changes the movement of electrons into mechanical movement4 ,every living being1 and even man himself1 is but a transformer of energy1 changing the energy derived from the earth and air and sun into mechanical motion1 nervous energy1 and heat4 ,the first law of energetics1 that of the conservation of energy1 is analogous to ,lavoisier's principle in chemistry1 the conservation of matter4 ,the sign of equality which unites the terms of a chemical equation expresses the fact that after every chemical reaction the same total mass of matter is present as before the transformation4 ,this is also true of energy2 after every transformation we find exactly the same total quantity of energy as before it4 ,this1 however1 tells us nothing as to the conditions of the transformation1 or the causes1 i4e4 the anterior phenomena1 which determined such transformation4 ,the second principle of energetics1 that of ,carnot1 enunciated in #ahbd1 deals with the conditions under which a transformation of energy is possible4 ,a mass of water at a certain height represents a quantity of potential energy equal to the product of its weight by its height2 but this energy cannot produce mechanical work unless the water is allowed to fall4 ,consider two lakes at the same altitude and of the same capacity1 one of which is entirely landlocked1 while the other has an open channel leading to the sea4 ,each lake represents the same quantity of potential energy1 but the energy of the landlocked lake is useless1 it cannot be #ajc transformed2 whereas the other lake whose water can run into the sea realizes the conditions necessary for utilization1 viz4 the transformability of its energy4 ,the same may be said of all forms of energy2 a heat engine can only act as a transformer1 change heat into work1 if there is a difference of temperature between its source and its sink2 an electric motor can only work if there is a fall of potential between the entrance and the exit of the electric current4 ,energy presents itself to us as the product of two factors1 weight and height in the waterfall1 quantity and temperature in the heat engine1 current intensity and potential in the electric motor4 ,in considering these two factors we may note that one factor is always a quantity 7,q7 and the other an intensity 7,i74 ,this latter expresses some sort of difference of position or condition1 the height of the weight1 a difference of temperature in the heat engine1 of pressure in the gas engine1 or of electric potential in the dynamo or electric furnace4 ,there can be no current of energy without this difference of potential1 and therefore no transformation from one form of energy to another4 ,the second law of thermodynamics1 ,carnot's law1 may therefore be enunciated thus3 ,energy cannot be transformed without a fall of potential4 ,we may also derive this principle from a consideration of the formula of efficiency1 the ratio of the work done by the transformer to the work done on the transformer4 ,efficiency energy transformed _/ total energy absorbed ,the total energy is the product ,,qi1 i4e4 the product of the total quantity by the total intensity at our disposal4 ,the transformed energy is ,q7,i - ,i'71 the product of the total quantity by the difference of intensity at the inlet and at the outlet of the machine4 ,the formula for efficiency thus becomes ,q7,i - ,i'7 _/ ,,qi 7,i - ,i'7 _/ ,i4 ,if ,i represents a temperature1 then in order that the efficiency may be positive ,i' must be less than ,i1 #ajd there must be a fall of temperature in the machine4 ,if ,i' were greater than ,i1 i4e4 if the temperature at the outlet were greater than that at the inlet1 the efficiency would be a negative one1 and the transformer would have to borrow heat from some external source4 ,entropy4--,in every transformation of energy a certain portion of the energy is transformed into heat3 a lamp gives out useless heat as well as light1 a machine gives out useless heat as well as mechanical work4 ,this loss of useful energy as heat occurs in every transference or transformation of energy2 it is only in the case of heat passing from a hotter to a colder body that there is no such transformation4 ,when equality of temperature is established there has been no loss of energy1 but the whole of the energy has become unutilizable1 i4e4 untransformable4 ,in the formula of efficiency the fall of intensity ,i - ,i' is now zero1 and therefore the efficiency of the machine 7,i - ,i'7 _/ ,i is also zero4 ,since in all its transformations a certain fraction of the energy is changed into heat1 there is a tendency in nature for all differences of temperature to become equalized4 ,hence the quantity of utilizable energy in the universe tends to diminish4 ,clausius called this unutilizable energy enmeshed in the substance of a body its entropy1 and showed that in every transformation the amount of this unutilizable energy tended to increase4 ,the entropy of a system always tends towards a maximum value4 ,if this gradual incessant increase of entropy is universal in nature1 and if there is no compensatory mechanism1 the universe must be tending towards a definite end1 when the whole of its energy shall have been transformed into unutilizable heat with a uniform temperature4 ,there is1 however1 reason to suppose that some such compensatory mechanism does in fact exist4 ,behind us stretches an infinite past1 and in the future we believe that the phenomena of nature will be unrolled in a cycle which has no end4 ,but the arguments derived from a study of entropy apply only to the facts and phenomena actually under our notice1 the supposed #aje impossibility1 without borrowing energy from without1 of re-establishing the differences of temperature by drawing heat from a colder in order to concentrate it in a hotter body1 and may not be absolutely identical with those obtaining in other ages4 ,our ignorance of such a phenomenon and our powerlessness to produce it in no way argue that it is impossible4 ,it may exist for aught we know in some other region of space1 or in another time than ours4 ,we may perhaps some day obtain artificially the conditions which would render possible such a phenomenon1 since it may be possible to produce in the experimental laboratory conditions which are not spontaneously realized in nature under present conditions4 ,the future may perchance reveal to us absolutely new phenomena which have not hitherto been realized4 ,in his work on the evolution of matter and of energy ,gustave le ,bon gives expression to some interesting and original ideas on this subject4 ,the laws of ,mayer and ,carnot alone are not sufficient to explain the phenomena of life1 without some consideration of the laws of stimulus4 ,mayer's principle asserts the conservation of energy1 and ,carnot's the conditions necessary for its transformation1 but these alone cannot account for the transformation of potential into actual energy4 ,a weight suspended by a cord does not fall merely because there is room for its descent4 ,we need the intervention of some outside force to cut the cord4 ,in every transformation of energy this external force is required to cut the cord1 or pull the trigger1 some external force of excitation or liberation1 an energy which may be infinitesimal in amount1 and which bears no proportion to the quantity of potential energy it sets free4 ,this intervention of an excitatory1 stimulating1 or liberating energy is universal4 ,every phenomenon of nature is but a transformation or a transference of energy1 determined by the intervention of a minimal quantity of energy from without4 ,this liberation of large quantities of potential energy by an exceedingly small external stimulus has not hitherto received the consideration it demands4 ,certain phenomena1 such as those of chemical catalysis or the action of soluble ferments1 excite our astonishment because such extremely small quantities of #ajf certain substances will determine the chemical transformations of large quantities of matter1 there being no proportion between the amount of the catalytic substance and of the matter transformed4 ,these phenomena are1 however1 only particular cases of the general law of energetics that transformation requires a stimulus4 ,the catalyzer1 or ferment1 does not contribute matter to the reaction1 but only the minimal energy necessary to liberate the chemical potential energy stored in the fermenting substance4 ,we must therefore add a third to the two laws of energetics1 ,mayer's law of conservation1 and ,carnot's law of fall of potential4 ,this third law is the law of stimulus1 the necessity of the intervention of an external excitatory force capable of setting in motion the current of energy required for a transformation4 ,this stimulus is the primary phenomenon1 the determinant cause of such transformation4 ,three conditions1 then1 are required for a transformation or displacement of energy3-- #a4 ,the cause1 the intervention of a stimulus which starts the transformation or displacement4 #b4 ,the possibility1 the necessary fall of potential4 #c4 ,the condition1 the conservation of the energy concerned1 since being indestructible its total quantity cannot alter4 ,every living being is a transformer of energy4 ,the lower animals and man himself receive from food and air the potential energy which becomes actual under the process of oxydation4 ,this chemical combustion is the source of all vital energy2 the ancients aptly compared life to a flame1 and ,lavoisier has shown that life1 like the flame1 is maintained by a process of oxydation4 ,the energy derived from food and air is restored by the organism to the external world in the form of heat and mechanical motion4 ,the celebrated experiments of ,atwater show that there is an absolute equality between the energy obtained from the oxydation of the various aliments and the sum of the calorific and mechanical energy liberated by a living being4 ,man obtains his supply of energy either directly from the #ajg vegetable world1 or indirectly from vegetables which have passed through the flesh of animals4 ,vegetables in their turn obtain their substance from the mineral world and their energy from the sun4 ,the salts1 the water1 and the carbonic acid absorbed by plants possess no store of potential energy4 ,whence then can they obtain the potential energy which they transmit to animals and man1 if not from the sun8 ,the energy of the solar radiations is absorbed by the chlorophyll of the leaves1 and stored up in the organic carbohydrates formed by the synthesis of water and carbon4 ,chlorophyll has the peculiar property of reducing carbonic acid1 and uniting the carbon with water in different proportions to form sugar and starch1 whilst fats and vegetable albumens are also formed by an analogous reaction4 ,all these complex bodies are stores of energy2 the vital processes of oxydation do but liberate in the human body the energy which the chlorophyll of plants has absorbed from the solar rays4 ,we must look1 then1 to the sun as the direct source of all the energy which animates the surface of the earth4 ,the sun looses the winds1 and raises the waters of the sea to the mountain-tops1 to form the rivers and torrents which return again to the sea2 the sun warms our hearths1 drives our ships1 and works our steam engines4 ,there is no sign of life or movement on our planet which does not come directly or indirectly from the solar rays4 ,it may be asked by what path does the chemical energy of the living organism pass into the mechanical energy of motion4 ,it would appear that the intermediary step cannot be heat1 as in the steam engine1 since the necessary temperature would be quite incompatible with life4 ,the formula for the efficiency of a thermic transformer is 7,t - ,t'7 _/ ,t1 the ratio of the difference of the absolute temperatures at the source and at the sink1 to the absolute temperature at the source4 ,calorimetric measurements have shown that the efficiency of the human machine is about one-fifth1 i4e4 it can transform #bj per cent4 of the energy absorbed4 ,the ordinary temperature of muscle is #ch;deg ,c41 or #caa;deg absolute4 ,we have #ajh therefore 7,t - #caa7 _/ ,t 4#bj1 or ,t #chh4ge;deg absolute1 i4e4 #aae4ge;deg ,c4 ,thus1 in order to obtain an efficiency of #bj per cent4 with an ordinary thermic transformer1 having a temperature of #ch;deg at the sink1 we should need a temperature of over #aae;deg ,c4 at the source4 ,such a temperature would be quite incompatible with the integrity of living tissues1 and we may therefore conclude that the human organism is not a heat engine4 ,we are indeed completely ignorant of the mode of transformation of chemical into kinetic energy in the living organism2 we know only that muscular contraction is accompanied by a change of form2 at the moment of transformation the combustion of the muscle is increased1 and during contraction the stretched muscular fibre tends to acquire a spherical shape4 ,it is this shortening of the muscular fibre which produces the mechanical movement4 ,the step which we do not as yet fully understand is the physical phenomenon which intervenes between the disengagement of chemical energy and the occurrence of muscular contraction4 ,professor d',arsonval supposes that this missing step is a variation in the surface tension of the liquid in the muscular fibre4 ,the surface tension of a liquid is due to the unbalanced forces of cohesion acting on the surface layer of molecules4 ,under the attraction of cohesion the molecules within the liquid are in a state of equilibrium1 being equally attracted in all directions1 but those at the surface of the liquid are drawn towards the centre4 ,the resultant of these attractive forces is a pressure normal to the surface1 which is mechanically equivalent to an elastic tension tending to diminish the surface4 ,in consequence of this surface tension the liquid has a tendency to assume the form in which its surface area is a minimum1 i4e4 the spherical form4 ,if such a sphere is stretched into a cylinder or fibre by mechanical tension1 it will shorten itself when released2 and if by any means we increase the surface tension of such a liquid fibre it will tend to assume a spherical form and contract just as a muscular fibre does4 ,the surface tension of a liquid varies with its chemical composition2 the slightest chemical modification of a liquid alters the force of #aji this tension4 ,we may therefore explain the mechanism of muscular contraction by supposing that a nervous impulse alters in some way the rate of combustion in a muscular fibre1 that this alteration produces a momentary change in the chemical composition of the muscular cell1 and that this change of chemical composition increases the surface tension of the cell sufficiently to provoke its contraction into a more spherical form4 ,ostwald has introduced a very useful conception for the study of this question of surface energy4 ,a liquid surface contains a quantity of energy equal to its surface tension multiplied by its area1 hence any variation either of area or of tension corresponds to a variation of its energy4 ,this novel conception constitutes a valuable addition to the experimental study of the physiology of muscular action1 since it gives us some idea of the mechanism by which chemical energy may be transformed into muscular contraction4 ,whatever the mechanism of transformation in the animal machine1 we have to consider the same quantities as in other motor machines4 ,these are3 7#a7 the efficiency2 7#b7 the potential energy2 7#c7 the power2 7#d7 the energy given up to the medium under the form of heat2 7#e7 the temperature4 ,muscles1 then1 are merely transformers which change chemical energy into mechanical work1 the diminution of stored-up energy in a muscle being expressed by the sensation of fatigue4 ,a muscle may be studied in four different phases3 7#a7 in repose2 7#b7 in a state of tension2 7#c7 when doing positive work2 7#d7 when work is being done on it4 ,when a muscle is in a state of tension1 as when a weight is sustained by the outstretched arm1 the muscle is producing no external work4 ,the entire work done is converted into heat2 just as it is in a dynamo or steam engine which is prevented from turning by a brake4 ,muscular contraction produces fatigue even when it does no external work4 ,it is impossible for the muscle to support even the weight of the outstretched arm itself for any considerable time4 ,a muscle is doing positive work when it is raising a weight or moving a body from one point to another4 #aaj ,the fourth state of muscular contraction is when the muscle is doing negative work1 i4e4 when work is being done on it1 as for instance when we go downstairs1 or when a descending weight forces down the opposing arm which attempts to support it4 ,in this case the muscles receive a portion of the energy lost by the descending weight1 and this energy shows itself in the muscle in the form of heat4 ,this increase of heat in a muscle doing negative work has been clearly demonstrated by the calorimetric experiments of ,hirn and the thermometric experiments of ,beclard4 ,hirn's observations on muscular calorimetry show a production of heat corresponding to #aej calories per hour when in repose1 #bdh calories per hour during positive work1 and #bhg during negative work4 ,beclard's thermometric measurements also show that the temperature of a muscle rises each time that it contracts1 and that the rise of temperature is greatest when the muscle is doing negative work1 least during positive work1 and intermediate when in a state of tension4 ,it is of the greatest importance in medical practice to distinguish between these different forms of muscular activity4 ,there is a vast physiological difference between muscular contraction with the production of positive work1 and muscular contraction without the production of work1 or with negative work4 ,to climb a flight of stairs is to contract the muscles with the production of work equal to the weight of the body multiplied by the height of the stairs4 ,to descend the stairs is to contract the same muscles1 but with the production of negative work1 and consequently a maximum of heat4 ,to walk on level ground is to contract the muscles with the production of little or no external work2 as in a machine turning without friction in a vacuum4 ,we have seen that a fall of potential and a current of energy are the necessary conditions for the production of any natural phenomenon4 ,hence we may assume that the phenomenon of sensation is also accompanied by a fall of potential and a current of energy4 ,when we touch a hot body1 there is a flow of energy from the hot body to the hand4 ,when we touch a cold body1 there is a current of energy in the opposite direction1 #aaa from the hand to the body4 ,it was formerly held1 and is still held by some physiologists1 that the chief characteristic of life is the disproportion between an excitation and the response which it invokes from the organism4 ,such a doctrine can only be held by one who believes1 at least implicitly1 that the phenomena of life are supernatural1 or at all events different in their nature from all other phenomena2 for the disproportion between an excitation and the response it evokes is by no means confined to living things4 ,this disproportion is universal in nature1 and quite in conformity with the physical laws which govern the transformation of energy4 ,the energy of living things is potential energy--a fact which has been too little recognized4 ,in the case of reflex actions it is self-evident1 because the response is immediate1 and always the same for the same stimulus4 ,as in all other transformations1 the stimulus consists in the intervention of a minimal quantity of external energy4 ,long before the discovery of the laws of energy1 ,lamarck had recognized and formulated this fact4 ,he writes3 ,what would vegetable life be without excitations from without1 what would be the life even of the lower animals without this cause8 ,in another passage1 seeking for a power capable of exciting the action of the organism1 he says3 ,the lower animal forms1 without nervous system1 live only by the aid of excitations which they receive from without4 ,in the lowest forms of life this exciting force is borrowed directly from the environment1 while in the higher forms the external exciting force is transferred to the interior of the living being and placed at the disposal of the individual4 ,this remark1 that the movements of living things are not communicated but excited1 that the external excitation only sets free latent or potential energy in the organism1 shows that ,lamarck had penetrated more deeply than many of the modern physiologists into the secrets of biological energy4 ,we seek in vain in the text-books of physiology for any conception of potential energy in living beings1 or the notion of an exciting force as the cause of sensation4 ,all action of a living organism is reflex action4 ,every action has a cause1 and #aab the cause of an organic action is an exciting energy from without1 either immediate1 or stored up in the nervous system from an external impression made at some previous epoch4 ,actions which are not evidently reflex are merely delayed reflexes2 we have acquired the power of inhibiting1 delaying1 or modifying the response to an external stimulus1 so that the same excitation may determine responses of very different kinds according to the mood produced by previous impressions4 ,when carefully investigated1 no action of ours is automatic2 every movement is determined by impressions derived from without4 ,an action without a motive1 that is without an external determining cause1 would be an action without reason4 ,in conclusion1 we may formulate this general principle3 ,the energy of a living being is potential energy2 sensations represent the intervention of an external exciting energy which provokes the response1 i4e4 the transformation of the potential energy already stored in the organism into the actual energy of motion and vital activity4 99 99 99 99 99 #aac ,,chapter ,x ,,synthetic ,,biology ,the course of development of every branch of natural science has been the same4 ,it begins by the observation and classification of the objects and phenomena of nature4 ,the next step is to decompose the more complex phenomena in order to determine the physical mechanism underlying them--the science has become analytical4 ,finally1 when the mechanism of a phenomenon is understood1 it becomes possible to reproduce it1 to repeat it by directing the physical forces which are its cause--the science has now become synthetical4 ,modern biology admits that the phenomena of life are physico-chemical in their nature4 ,although we have not as yet been able to define the exact nature of the physical and chemical processes which underlie all vital phenomena1 yet every further discovery confirms our belief that the physical laws of life are identical with those of the mineral world1 and modern research tends more and more to prove that life is produced by the same forces and is subject to the same laws that regulate inanimate matter4 ,the evolution of biology has been the same as that of the other sciences2 it has been successively descriptive1 analytical1 and synthetic4 ,just as synthetic chemistry began with the artificial formation of the simplest organic products1 so biological synthesis must content itself at first with the fabrication of forms resembling those of the lowest organisms4 ,like other sciences1 synthetic biology must proceed from the simpler to the more complex1 beginning with the reproduction of the more elementary vital phenomena4 ,later on we may hope to #aad unite and associate these1 and to observe their development under various external influences4 ,the synthesis of life1 should it ever occur1 will not be the sensational discovery which we usually associate with the idea4 ,if we accept the theory of evolution1 then the first dawn of the synthesis of life must consist in the production of forms intermediate between the inorganic and the organic world--forms which possess only some of the rudimentary attributes of life1 to which other attributes will be slowly added in the course of development by the evolutionary action of the environment4 ,long ago1 the penetrating genius of ,lamarck seized on the idea that a knowledge of life could only be obtained by the comparison of organic with inorganic phenomena4 ,he writes3 ,if we would acquire a real knowledge of what constitutes life1 of what it consists1 what are the causes and the laws which give rise to this wonderful phenomenon of nature1 and how life can be the source of the multitude of forms presented to us by living organisms1 we must before all consider with great attention the differences which exist between inorganic and living bodies2 and for this purpose we must compare side by side the essential characters of these two classes of bodies4 ,synthetic biology includes morphogeny1 physiogeny1 and synthetic organic chemistry1 which is also a branch of synthetic biology1 since it deals with the composition of the constituents of living organisms4 ,synthetic organic chemistry is already a well-organized science1 important by reason of the triumphs which it has already gained4 ,the other two branches of biological synthesis1 morphogeny1 the synthesis of living forms and structures1 and physiogeny1 the synthesis of functions1 can hardly as yet be said to exist as sciences4 ,they are1 however1 no less legitimate and no less important than the sister science of synthetic chemistry4 ,although morphogeny and physiogeny do not exist as well-organized and recognized sciences1 there are already a number of works on the subject by enthusiastic pioneers--independent seekers1 who have not feared to abandon the paths of official science to wander in new and hitherto unexplored domains4 #aae ,the first experiment in physiogeny was the discovery of osmosis by the ,abbe ,nollet in #agdh4 ,he filled a pig's bladder with alcohol1 and plunged it into water4 ,he noticed that the bladder gradually increased in volume and became distended1 the water penetrating into the interior of the bladder more quickly than the alcohol could escape4 ,this was the first recorded experiment in the physics of nutrition and growth4 ,in #ahff1 ,moritz ,traube of ,breslau discovered the osmotic properties of certain chemical precipitates4 ,as ,i pointed out in the ,revue ,scientifique of ,march #aijf1 ,traube made the first artificial cell1 and studied the osmotic properties of membranes and their mode of production4 ,this remarkable research should have been the starting-point of synthetic biology4 ,the only result1 however1 was to give rise to numberless objections1 and it soon fell into complete oblivion4 ,there are1 says ,traube1 a number of persons quite blind to all progress1 who in the presence of a new discovery think only of the objections which may be brought against it4 ,the works of ,traube have been collected and published by his son 7,gesammelte ,abhandlungen von ,moritz ,traube1 #ahii74 ,in #ahfg there appeared in ,england a paper by ,dr4 ,e4 ,montgomery1 of ,st4 ,thomas's ,hospital1 ,on the ,formation of so-called ,cells in ,animal ,bodies4 ,this paper1 published by ,churchill ,sons1 is a most interesting contribution and one of great originality4 ,the author says3 ,there can be no compromise between the tenets of the cell theory and the conclusions arrived at in this paper2 the distinction is thorough4 ,either the units of which an organism is composed owe their origin to some kind or other of procreation1 a mysterious act of that mysterious entity life1 by which1 in addition to their material properties1 they become endowed with those peculiar metaphysical powers constituting vitality4 ,or1 on the other hand1 the organic units1 like the crystalline units of inorganic bodies1 form the organism by dint of similar inherent qualities1 form in fact a living being possessed of all its inherent properties1 as soon as certain chemical compounds are placed under certain physical conditions4 ,if the former opinion be #aaf true1 then we must clearly understand that there exists naturally a break in the sequence of evolution1 a chasm between the organic and the inorganic world never to be bridged over4 ,if1 on the contrary1 the latter view be correct1 then it strongly argues for a continuity of development1 a gradual chemical elaboration1 which culminates in those high compounds which1 under surrounding influences1 manifest those complex changes called vital4 ,surely it is not a matter of indifference or of mere words1 if the extreme aim of physiology avowedly be the detection of the different functions dependent on the vital exertions of a variety of ultimate organisms1 and the discovery of the specific stimulants which naturally incite these functions into play4 ,or1 on the other hand1 if it be understood to consist rather in the careful investigation of the succession of chemical differentiations and their accompanying physical changes1 which give rise to the formation of a variety of tissues that are found to possess certain specific properties1 to display certain definite actions due to a further flow of chemical and physical modifications4 ,in #ahga there appeared a memoir by the ,dutch savant ,harting entitled ,recherche de ,morphologie synthetique sur la production artificielle de quelques formations calcaires organiques4 ,this memoir1 says ,professor ,r4 ,dubois1 had cost ,harting more than thirty years of work4 ,synthetic morphology is yet only in its infancy1 let us hope that in a time equal to that which has already expired since the first artificial production of urea1 it will have made a progress equal to that of its older sister1 synthetic chemistry4 ,in the ,comptes ,rendues of #ahhb is the following note by ,d4 ,monnier and ,karl ,vogt3-- #a4 ,figured forms presenting all the characteristics of organic growth1 cells1 porous canals1 tubes with partition walls1 and heterogeneous granules1 may be produced artificially in appropriate liquids by the mutual action of two salts which form one or more insoluble salts by double decomposition4 ,one of the component salts should be in solution1 while the other salt must be introduced in the solid form4 #aag #b4 ,such forms of organic elements1 cells1 tubes1 etc41 may be produced either in an organic liquid or a semi-organic liquid such as sucrate of lime1 or in an absolutely inorganic liquid such as silicate of soda4 ,thus there can no longer be any question of distinctive forms as characterizing organic bodies in contradistinction to inorganic bodies4 #c4 ,the figured elements of these pseudo-organic forms depend on the nature1 the viscosity1 and the concentration of the liquids in which they are produced4 ,certain viscous liquids such as solutions of gum arabic or chloride of zinc do not produce these forms4 #d4 ,the form of these artificial pseudo-organic products is constant1 as constant as that of the crystalline forms of mineral salts4 ,this form is so characteristic that it may often serve for the recognition of a minimal proportion of a substance in a mixture4 ,the observation of these forms is a means of analysis as sensitive as that of the spectrum4 ,we may1 for example1 differentiate in this way the alkaline bicarbonates from the sesqui-carbonates or the carbonates4 #e4 ,the form of these artificial pseudo-organic elements depends principally on the nature of the acid radical of the solid salt4 ,thus the sulphates and the phosphates generally produce tubes1 while the carbonates form cells4 #f4 ,as a rule these pseudo-organic forms are engendered only by substances which are found in the living organism4 ,thus sucrate of calcium will engender organic forms1 whereas sucrate of strontium or barium does not do so4 ,there are1 however1 some exceptions to this rule1 such as the sulphates of copper1 cadmium1 zinc1 and nickel4 #g4 ,these artificial pseudo-organic elements are surrounded by veritable membranes1 dializing membranes which allow only liquids to pass through them4 ,these artificial cells have heterogeneous cell-contents1 and produce in their interior granulations which are disposed in a regular order4 ,thus they are both in constitution and in form absolutely similar to the cellular elements which constitute living organisms4 #h4 ,it is probable that the inorganic elements which are present in the natural protoplasm may play an important part #aah in determining the form which is assumed by the figured elements of the organism4 ,in #aijb1 ,professor ,quinke of ,heidelberg1 who has consecrated his life with such distinction to the physics of liquids1 writes thus of the organogenic power of liquids in a paper published in the ,annalen der ,physik under the title ,unsichtbare ,fluessigkeitschichten3 ,in #ahcg1 ,gustav ,rose obtained organic forms by precipitation from inorganic solutions4 ,by precipitating chloride of calcium with the carbonates of ammonium and other alkaline carbonates1 he obtained small spheres which grew and were transformed into calcic rhombohedra4 ,he also obtained a flocculent precipitate which later became granular and showed under the microscope forms like the starfish1 and discs with undulated borders4 ,at ,freiberg1 in certain stalactites1 ,rose also discovered forms consisting of six pyramidal cells around a spherical nucleus4 ,in #ahci1 ,link obtained spherical granulations by the precipitation of calcic or plumbic solutions by potash1 soda1 or carbonic acid4 ,these spherical granulations united after a time to form crystals4 ,sulphate of iron1 ammoniated sulphate of zinc1 sulphate of copper precipitated by sulphuretted hydrogen1 and saline solutions precipitated by ferrocyanide of potash1 all give granular precipitates or discs1 of which the granular origin is quite perceptible4 ,runge in #ahee was the first to describe the formation of periodic chemical precipitates4 ,he used blotting paper as the medium in which various chemical substances met by diffusion4 ,in this way he studied the mutual reactions of solutions of ferrocyanide of potash1 chloride of iron1 and the sulphates of copper1 iron1 manganese1 and zinc4 ,the coloured precipitates appeared at different positions in the paper1 and disappeared periodically at greater or longer intervals4 ,the designs formed by these coloured precipitates change with the concentration of the saline solutions1 or on the addition of oxalic acid1 salts of potash or ammonia1 and other substances4 ,these designs are shown in a number of beautiful illustrations which accompany the work4 ,in this #aai case the capillarity of the paper necessarily exerts a certain influence on the formation of the figures1 but in addition to this1 ,runge admits the intervention of another force hitherto unknown1 which he calls ',bildungstrieb1' the formative impulse1 which he considers to be the elementary vital force in the formation of plants and animals4 ,in #ahfg1 ,r4 ,boettger obtained arborescent forms and ramifications of metallic vegetation by sowing fragments the size of a pea of crystals of the iron chlorides1 chloride of cobalt1 sulphate of manganese1 nitrate and chloride of copper1 etc41 in an aqueous solution of silicate of sodium of specific gravity #a4ah4 ,these forms are due1 as ,i shall show later on1 to the surface tension of the oily precipitate2 ,boettger gives no explanation of the phenomenon4 ,to this force1 viz4 that of surface tension1 is also due the cellular forms obtained by ,traube in #ahff4 ,these were obtained from gelatine and tannin1 from acetate of copper or lead1 and from nitrate of mercury in an aqueous solution of ferrocyanide of potassium4 ,these cells and precipitated membranes have also been studied by ,reinke1 ,f4 ,cohn1 ,h4 de ,vries1 and myself1 who all observed the regression of these membranes1 which although colloidal at the beginning of the reaction speedily become friable4 ,this entirely refutes the opinion of ,traube as to the constitution of the precipitated membranes4 ,he supposed them to consist of masses of solid substance1 with smaller orifices which do not permit the passage of the membranogenous substance1 whilst the larger orifices through which it can pass are soon closed by the precipitate1 the membrane itself thus growing by a process of intussusception4 ,later on ,traube himself considered the precipitated membrane to be a thin1 solid gelatinous layer in which the water was mechanically entangled4 ,tamman has also made a number of experiments with solutions of the chlorides and sulphates of the heavy metals1 and solutions of phosphates1 silicates1 ferrocyanides1 and other salts4 ,he found that most of these membranes were permeable to the membranogenous solution4 ,according to ,tamman1 all #abj precipitated membranes are hydrated substances1 and some of them1 like the ferrocyanide of copper and the tannate of gelatine are1 when first formed1 entirely comparable to liquid membranes in all their properties4 ,graham had already obtained colourless jellies by the interaction of concentrated solutions of ferrocyanide of potassium and sulphate of copper4 ,buetschli also has recently described the microscopic appearance of precipitated membranes produced by ferrocyanide of potassium and acetate or chloride of iron4 ,like ,linke and ,gustav ,rose1 ,famintzin has obtained spheroidal precipitates by the reciprocal action of concentrated solutions of chloride of calcium and carbonate of potassium4 ,these grow rapidly and suddenly1 with concentric layers showing a spherical or flattened nucleus4 ,he also obtained forms resembling sphero-crystals and starch grains4 ,harting1 ,vogelsang1 ,hansen1 ,buetschli1 and others have studied the structures which are formed by the reciprocal action of chloride of calcium and the alkaline carbonates4 ,vogelsang has found small calcareous bodies in the amorphous and globular precipitate formed by chloride of calcium and carbonate of ammonium4 ,he describes spheres attached to one another1 vesicles1 and muriform structures4 ,the number of these spheroids is increased by the addition of gelatine4 ,hansen has also studied ,harting's method for the formation of sphero-crystals by the action of the alkaline carbonates and phosphates on the salts of calcium in presence of albumen and gelatine4 ,he considers that the latter retard the crystallization and assist the formation of the sphero-crystals4 ,i shall show later on that gelatine and albumen essentially modify the precipitate and do not merely act as catalytic substances4 ,the researches of ,famintzin1 repeated and extended by ,buetschli1 show that sphero-crystals are produced by the reaction of chloride of calcium on carbonate of potassium without the presence of gelatine or albumen4 ,buetschli studied the spheroids of carbonate of lime by means of polarized light1 and found that the layers were alternately positively and negatively polarized4 #aba ,such is the history of morphogenesis as described in #aijb by the authority most qualified for the task1 ,professor ,quinke of ,heidelberg4 ,in #aijd1 ,professor ,moritz ,benedikt of ,vienna treated the whole question in his book1 ,crystallization and ,morphogenesis1 of which a ,french translation appeared in the ,maloine ,library4 ,this book is full of original and suggestive ideas2 it describes the work of ,harting1 and more especially that of ,van ,schroen1 who considers that crystals like living beings begin as a cell and grow by a process of intussusception4 ,professor ,benedikt has made a complete resume of the question in an article1 ,the ,origins of the ,forms of ,life1 which appeared in the ,revue ,scientifique in #aije4 ,in #aijd1 ,professor ,dubois of ,lyons presented a report to the ,society of ,biology on his interesting experiments on mineral cytogenesis4 ,the same year he gave a discourse at the university of ,lyons on ,the ,creation of ,living ,beings1 which has been published by ,a4 ,storck of ,lyons4 ,one of the most active of the modern morphogenists is ,professor ,herrera of ,mexico1 whose work is illustrated in the ,atlas de ,plasmogenie by ,dr4 ,jules ,felix of ,brussels1 one of the most enthusiastic disciples of the new science4 ,there is a resume of ,herrera's work in the ,memoirs of the ,societe ,alzate1 ,mexico4 ,a bibliography of the works which have appeared on this subject may be found in the book of ,professor ,rhumbler of ,goettingen1 ,aus dem ,lueckengebiete zwischen ,organischer und ,anorganischer ,materie1 #aijf4 ,in #aijg1 ,dr4 ,luiz ,razetti of ,carracas published a magnificent study of the subject under the title ,que es la vida4 ,in #aijg1 ,dr4 ,martin ,kuckuck of ,st4 ,petersburg repeated and extended the experiments of ,r4 ,dubois1 and published his results under the title ,archigonia1 ,generatio ,spontanea1 ,leipzig1 ,ambrosius ,barth4 ,butler ,burke of ,cambridge has also made a series of experiments with radium and barium salts analogous to those of ,dubois4 ,in #aiji1 ,albert and ,alexandre ,mary of ,beauvais published #abb an interesting study of this question under the title ,etudes experimentales sur la generation primitive1 published by ,jules ,rousset4 ,i should mention also among the works of synthetic biology the publications of ,professor ,otto ,lehmann of ,karlsruhe1 and in particular ,fluessige ,krystalle und die ,theorien des ,lebens1 ,leipzig1 ,ambrosius ,barth4 ,professor ,ulenhuth of ,berlin has published his study on the osmotic growth of iron in alkaline hypochlorites under the title ,untersuchungen ueber ,antiformin1 ,berlin1 ,julius ,springer4 ,professor ,gariel has made a series of researches on osmotic growth which are published in ,abraham's ,recueil d'experiences de physique4 ,a4 ,lecha ,marzo of ,valladolid published his researches on the growth of aniline colours in the ,gaceta ,medica ,catalana1 #aiji1 under the title ,otra nueva flora artificiale4 ,dr4 ,maurice d',halluin of ,lille has also published a volume on osmotic growths under the title1 ,stephane ,leduc a-t-il cree la vie8 ,the subjects of the numerous memoirs that ,i have myself published during the last ten years upon the question are treated anew in the pages of this volume1 and a resume of my researches on osmotic growth has already appeared in the ,documents du ,progres1 ,sept4 #aiji4 ,we have thus shown that synthetic morphogenesis has already attracted the attention of a certain number of ardent investigators4 ,morphogeny has now its methods and its results1 and physiogeny is also developing side by side with it1 since function is but the result of form4 ,the field of research is opened1 and workers alone are needed in order to reap an abundant harvest4 99 99 99 99 99 #abc ,,chapter ,,xi ,,osmotic ,,growth--,a ,,study ,,in ,,morphogenesis ,the phenomenon of osmotic growth has doubtless presented itself to the eyes of every chemist2 but to discover a phenomenon it is not enough merely to have it under our eyes4 ,before ,newton many a mathematician had seen a spectrum1 if only in the rainbow2 many an observer before ,franklin had watched the lightning4 ,to discover a phenomenon is to understand it1 to give it its due interpretation1 and to comprehend the importance of the role which it plays in the scheme of nature4 ,osmotic ,membranes4--,certain substances in concentrated solution have the property of forming osmotic membranes when they come in contact with other chemical solutions4 ,when a soluble substance in concentrated solution is immersed in a liquid which forms with it a colloidal precipitate1 its surface becomes encased in a thin layer of precipitate which gradually forms an osmotic membrane round it4 ,an osmotic membrane is not a semi-permeable membrane1 as sometimes described1 i4e4 a membrane permeable to water but impermeable to the solute4 ,it is a membrane which opposes different resistances to the passage of water and of the various substances in solution1 being very permeable to water1 but much less so to the different solutes4 ,a soluble substance thus surrounded by an osmotic membrane represents what ,traube has called an artificial cell4 ,in such a cell the dissolved substances have a very high osmotic pressure1 an expansive force like that of steam in a boiler2 the molecules of the solute exerting pressure on the walls of the extensible cell1 and distending it like the #abd gas in a balloon4 ,this pressure increases the volume of the cell1 and in consequence water rushes in through the permeable membrane and still further distends the cell4 ,most beautiful osmotic cells may be produced by dropping a fragment of fused calcium chloride into a saturated solution of potassium carbonate or tribasic potassium phosphate1 the calcium chloride becoming surrounded by an osmotic membrane of calcium carbonate or calcium phosphate4 ,this mineral membrane is beautifully transparent and perfectly extensible4 ,it is astonishing to contemplate the contrast between the hard crystalline forms of ordinary chalk and these soft transparent elastic membranes which have the same chemical constitution4 ,these osmotic cells of carbonate of lime or phosphate of lime consist of a transparent membrane enclosing liquid contents and a solid nucleus of chloride of calcium4 ,their form is that of an ovoid or flattened sphere1 and they may attain a diameter of seven centimetres or more4 ,more frequently the osmotic growth consists of a number of cells instead of one large cell4 ,the first cell gives birth to a second cell or vesicle1 and this to a third1 and so on1 so that we finally obtain an association of microscopic cellular cavities1 separated by osmotic walls--a structure completely analogous to that which we meet with in a living organism4 ,we may easily picture to ourselves the mechanism by which an osmotic cell gives birth to such a colony of microscopic vesicles4 ,the membranogenous substance1 the chloride of calcium1 diffuses uniformly on all sides from the solid nucleus1 and forms an osmotic membrane where it comes into contact with the solution4 ,this spherical membrane is extended by osmotic pressure1 and grows gradually larger4 ,since the area of the surface of a sphere increases as the square of its radius1 when the cell has grown to twice its original diameter1 each square centimetre of the membrane will receive by diffusion but a quarter as much of the membranogenous substance4 ,hence1 after a time1 the membrane will not be sufficiently nourished by the membranogenous substance1 it will break down1 and an aperture will occur through which the interior liquid oozes out1 forming in its turn a new #abe membranous covering for itself4 ,this is the explanation of the fact that all living organisms are formed by colonies of microscopical elements1 although we must not forget that ,nature often produces similar results in different ways4 ,illustration3 ,,fig4 #ce4 ,,fig4 #cf4 ,osmotic growths of ferrocyanide of copper4 ,osmotic growths may be obtained from a great number of chemical substances4 ,the most easily grown are the soluble salts of calcium in solutions of alkaline phosphates and carbonates1 to which we have already alluded4 ,we may also reverse the phenomenon by growing phosphates and carbonates in solutions of calcium salts1 but in this case the osmotic growths are not so beautiful4 ,the various silicates play an important part in the constitution of shells and of the skeletons of marine animals4 ,most of the metallic salts1 and more especially the soluble salts of calcium1 give rise to the phenomenon of osmotic growth when sown in solutions of the alkaline silicates4 ,in this way1 by using different silicates and varying the proportions and the concentrations1 we may obtain an immense variety of osmotic growths4 ,a good solution to commence with is the following3-- ,silicate of potash1 sp4 gr4 #a4c 7#cc;deg ,beaume7 #fj gr4 ,saturated solution of sodium carbonate #fj gr4 ,saturated solution of dibasic sodium phosphate #cj gr4 ,distilled water make up to #a litre4 #abf ,a fragment of fused calcium chloride dropped into this solution will produce a rapid growth of slender osmotic forms which may attain a height of #bj or #cj centimetres4 ,small pellets may also be made of one part of sugar and two of copper sulphate and sown in the following solution1 which must be kept warm until the growth is complete3-- ,ten per cent4 solution of gelatine #aj to #bj c4c4 ,saturated solution of potassium ferrocyanide #e to #aj c4c4 ,saturated solution of sodium chloride #e to #aj c4c4 ,warm water 7#cb;deg to #dj;deg ,c47 #ajj c4c4 ,in this solution we can obtain osmotic growths which may attain to a height of #dj centimetres or more1 vegetable forms1 roots1 arborescent twigs1 leaves1 and terminal organs4 ,these growths are stable as soon as the gelatine has cooled and set1 and may be carried about without fear of injury 7,fig4 #ce74 ,precipitated osmotic membranes are very widely distributed in nature4 ,professor ,ulenhuth has seen iron growths in alkaline sodium hypochlorite 7,javelle water71 and ,lecha-,marzo has demonstrated the osmotic growth of the various #abg stains used for microscopy1 in the liquids used for fixing preparations4 ,illustration3 ,,fig4 #cg4--,osmotic vermiform growth4 7a7 ,the sickle-shaped growth4 7b7 ,the growth broken by the upward pressure of the solution4 7c7 ,the wound having cicatrized1 the stem continues to grow downwards4 ,we now know that the physical force which builds up these growths is that of osmotic pressure1 since the slightest consideration will show the inadequacy of the usual explanation that the growth is due to mere differences of density1 or to amorphous precipitation around bubbles of gas4 ,these may indeed affect the phenomenon1 but can in no way be regarded as its cause4 ,one of our experiments throws considerable light on this question4 ,in a glass vessel we placed a concentrated solution of carbonate of potassium1 to which had been added #d per cent4 of a saturated solution of tribasic potassium phosphate4 ,into this solution we dropped a fragment of fused calcium chloride1 and obtained a vermiform growth some #f millimetres in diameter4 ,this growth was curved1 at first growing upwards1 then for a short distance horizontally1 and finally downwards4 ,the upward pressure of the solution1 which was heavier than the growth1 ultimately broke it at the top of the curve1 as shown at b1 ,fig4 #cg4 ,the liquid contents of the growth began to ooze out through the wound1 but this after a time became cicatrized1 and the stem continued to grow obstinately downwards once more1 in opposition to the hydrostatic pressure4 ,in consequence of this pressure the growth is sinuous1 tacking as it were from side to side like a boat against the wind4 ,we give three successive photographs of this growth1 which attained a length of over #aj inches4 ,we have frequently obtained these vermiform growths forming a series of such loops1 growing upwards and falling again many times in succession4 ,osmotic ,growths in ,air4--,certain of these artificial cells may be made to grow out of the solution into the air4 ,for this purpose we place a fragment of ,ca,cl#b in a shallow flat-bottomed glass dish1 just covering the fragment with liquid4 ,the best solution is as follows3-- ,potassium carbonate1 saturated solution #gf parts4 ,sodium sulphate1 saturated solution #bj ,tribasic potassium phosphate1 saturated solution #d #abh ,the calcium chloride surrounds itself with an osmotic membrane2 water penetrates into the interior of the cell thus formed1 and a beautiful transparent spherical cell is the result1 the summit of which soon emerges from the shallow liquid4 ,the cell continues to increase by absorption of the liquid at its base1 and may grow up out of the liquid into the air for as much as one or two centimetres4 ,this is a most impressive spectacle1 an osmotic production1 half aquatic and half aerial1 absorbing water and salts by its base1 and losing water and volatile products by evaporation from its summit1 while at the same time it absorbs and dissolves the gases of the atmosphere4 ,the aerial portion of an osmotic growth will sometimes become specialized in form4 ,the summit of the growth develops a sort of crown or cup surrounded by a circular wall4 ,this cup contains liquid1 and continues to grow up into the air like the stem of a plant1 carrying with it the liquid which has been absorbed by the base of the growth4 ,the preceding experiments give us an explanation of the curious phenomena exhibited by so-called creeping salts4 ,a saline solution left at the bottom of a vessel will sometimes be found after some months to have crept up to the top of the vessel4 ,cellular partitions formed in this way will be found extending from the bottom to the top of the vessel1 and not only so1 but the whole of the remaining liquid will be imprisoned in the upper cells4 ,illustration3 ,,fig4 #ch4--,osmotic growth produced by sowing a mixture of ,ca,cl#b and ,mn,cl#b in a solution of alkaline carbonate1 phosphate1 and silicate4 ,the stem and terminal organs are of different colours4 7,one-third of the natural size47 ,illustration3 ,,fig4 #ci4--;,an osmotic growth photographed by transverse light to show the construction of the terminal organs4 ,assimilation and ,excretion4--,like a living being1 an osmotic growth absorbs nutriment from the medium in which it grows1 and this nutriment it assimilates and organizes4 ,if we compare the weight of an osmotic growth with that of the mineral fragment which produced it1 we shall find that the mineral seed has increased many hundred times in weight4 ,similarly1 if we weigh the liquid before and after the experiment1 we shall find that it has lost an equivalent weight4 ,the absorbed substance of an osmotic production must also undergo chemical transformation before it can be assimilated--that is1 before it can form part of the growth4 ,calcium chloride1 for example1 growing in a solution of potassium #acj carbonate1 is transformed into calcium carbonate4 ,ca,cl#b ,k#b;,,co#c ,ca,c,o#c #b,k,cl4 ,thus an osmotic growth can make a choice between the substances offered to it1 rejecting the potassium of the nutrient liquid1 and absorbing water and the radical ,,co#c1 while at the same time it eliminates and excretes #aca chlorine1 which may be found in the nutrient liquid after the reaction4 ,of all the ordinary physical forces1 osmotic pressure and osmosis alone appear to possess this remarkable power of organization and morphogenesis4 ,it is a matter of surprise that this peculiar faculty has hitherto remained almost unsuspected4 ,illustration3 ,,fig4 #dj4--,osmotic growth in a solution of ,,kno#c1 showing spine-like organs4 ,osmotic ,growths4--,if we sow fragments of calcium chloride in solutions of the alkaline carbonates1 phosphates1 or silicates1 we obtain a wonderful variety of filiform and linear growths which may attain to a height of #cj or #dj centimetres4 ,some are so flexible that the stems bend1 falling in curves around the centre of growth1 like leaves of grass4 ,if we dilute this same liquid1 as it becomes less concentrated the growths are more curved1 ramified1 dendritic1 like those of trees or corals4 ,illustration3 ,,fig4 #da4--,terminal organs like catkins1 developing in a solution of ammonium chloride4 ,in the culture of osmotic growths we may also by appropriate means produce terminal organs resembling flowers and seed-capsules4 ,to do this we wait till the growth is considerably advanced1 and then add a large quantity of liquid to the nutrient solution so as to diminish the concentration a hundredfold or more4 ,spherical #acb terminal organs will then grow out from the ends of the stems1 which may during their further growth become conical or piriform in shape4 ,by superposing layers of liquid of different concentration and decreasing density1 one may obtain knots and swellings in the osmotic growths marking the surfaces of separation of the liquid4 ,when a young growth in the vigour of its youth reaches the surface of the water1 it spreads out horizontally over the surface of the liquid in thin leaves or foliaceous expansions of different forms4 ,illustration3 ,,fig4 #db4--;,an osmotic madrepore4 ,the preponderating influence in morphogenesis is osmotic pressure1 the osmotic forms varying with its intensity1 distribution1 and mode of application4 ,whatever the chemical composition of the liquid1 similar osmotic forces1 modified in the same manner1 give rise to forms which have a family resemblance4 ,the chemical nature of the liquid1 however1 is not entirely without influence on the form4 ,thus the presence of a nitrate in the mother liquor tends to produce points or thorns4 ,ammonium chloride in a potassium ferrocyanide solution produces growths shaped like catkins1 and the alkaline chlorides tend to produce vermiform growths4 #acc ,coralline growths may also be obtained by using appropriate chemical solutions4 ,for this purpose the solution of silicate1 carbonate1 and dibasic phosphate should be diluted to half strength1 with the addition of #b to #d per cent4 of a concentrated solution of sodium sulphate or potassium nitrate4 ,illustration3 ,,fig4 #dc4--;,an osmotic mushroom form4 ,illustration3 ,,fig4 #dd4--,osmotic fungi4 ,coral-like forms may also be grown from a semi-saturated solution of silicate1 carbonate1 and dibasic phosphate1 to which has been added #d per cent4 of a concentrated solution of sodium sulphate or potassium nitrate4 ,in this we may obtain beautiful growths like madrepores or corals1 formed by a central nucleus from which radiate large leaves like the petals of a flower4 ,the presence of nitrate of potassium produces pointed leaves with thorn-like processes recalling the forms of the aloe and the agave4 ,most remarkable fungus-like forms may be obtained by commencing the growth in a concentrated solution1 and then #acd carefully pouring a layer of distilled water over the surface of the liquid4 ,the resemblance is so perfect that some of our productions have been taken for fungi even by experts4 ,the #ace stem of these osmotic fungi is formed of bundles of fine hollow fibres1 while the upper surface of the cap is sometimes smooth1 and sometimes covered with small scales4 ,the lower surface of the cap shows traces of radiating lamellae1 which are sometimes intersected by concentric layers parallel to the outer #acf surface of the cap4 ,in this case the lower surface of the cap shows a number of orifices or canals similar to those seen in many varieties of fungus4 ,illustration3 ,,fig4 #de4--;,a shell-like calcareous osmotic growth4 ,illustration3 ,,fig4 #df4--,osmotic growths in the form of shells4 ,illustration3 ,,fig4 #dg4--;,capsular osmotic growth4 ,the capsule has been broken to show the interior structure4 ,shell-like osmotic productions may be grown by sowing the mineral in a very shallow layer of concentrated solution1 a centimetre or less in depth1 and pouring over this a less concentrated layer of solution4 ,by varying the solution or concentration we may thus grow an infinite variety of shell forms4 #acg ,capsules or closed shells may be produced in the same way by superimposing a layer of somewhat greater concentration4 ,these capsules consist of two valves joined together at their circumference4 ,the lower valve is thick and strong1 while the upper valve may be transparent1 translucent1 or opaque1 but is always thinner and more fragile than the lower one4 ,ferrous sulphate sown in a silicate solution gives rise to growths which are green in colour1 climbing1 or herbaceous1 twining in spirals round the larger and more solid calcareous growths4 ,illustration3 ,,fig4 #dh4--;,an osmotic growth in which the terminal organs are differently coloured from the stems1 showing that the chemical evolution is different4 ,with salts of manganese1 the chloride1 citrate or sulphate1 the stages of evolution of the growth are distinguished not only by diversities of form1 but also by modifications of colour4 ,we may thus obtain terminal organs black or golden yellow in colour on a white stalk4 ,in a similar way we may obtain fungi with a white stalk and a yellow cap1 of which the lower surface is black4 ,illustration3 ,,fig4 #di4--,osmotic capsular growth with figured belt4 ,very beautiful growths may be obtained by sowing calcium chloride in a solution of potassium carbonate1 with the addition of #b per cent4 of a saturated solution of tribasic potassium phosphate4 ,this will give capsules with figured belts1 vertical lines at regular intervals1 or transverse stripes composed of projecting dots such as may be seen in many sea-urchins4 ,these capsules are closed at the summit by a cap1 forming an operculum1 so that they sometimes appear as if formed of two valves4 ,now and again we may see the upper valve raised by #ach the internal osmotic pressure1 showing the gelatinous contents through the opening4 ,illustration3 ,,fig4 #ej4--;,amoeboid osmotic growth1 floating free in the mother liquor4 ,the calcareous capsules grown in a saturated solution of potassium carbonate or phosphate often take a regular ovoid form4 ,if these are allowed to thicken1 they may be taken out of the water without breaking1 and then present the aspect of veritable ooliths4 ,illustration3 ,,fig4 #ea4--,transparent osmotic cell1 in which may be seen the white calcareous nucleus4 ,the summit of the cell bears osmotic prolongations4 ,illustration3 ,,fig4 #eb4--;,amoeboid osmotic growth with long crystalline cilia swimming about in the mother liquor4 ,illustration3 ,,fig4 #ec4--,osmotic growth swimming in mother liquor4 ,the fin-like prolongation grew out between two liquid layers of different concentrations4 ,osmotic productions may be divided into two groups4 ,some like the silicate growths are fixed4 ,like vegetables1 they develop1 become organized1 grow1 decline1 die1 and are disintegrated at the spot where they are sown4 ,others1 especially those which are grown in alkaline carbonates and phosphates1 have two periods of evolution1 the first a fixed period1 and the second a wandering #aci one4 ,during the first period their specific gravity is greater than that of the surrounding medium1 and they rest immobile at the bottom of the vessel in which they are sown4 ,as they grow1 they absorb water and their specific gravity diminishes4 ,little by little they rise up in the liquid1 and finally acquire a considerable amount of mobility1 being readily displaced by every current4 ,hence it is very difficult to photograph these #adj mobile osmotic growths1 which swim about in the mother liquor and are often provided with prolongations in the forms of cilia1 and sometimes with fins1 which undulate as they move4 ,some of these ciliary hairs are evidently osmotic in their origin1 being localized as a tuft at the summit of the growth4 ,others are apparently crystalline in structure1 and are spread over the whole surface of the swimming vesicle4 ,an osmotic growth increases by the absorption of water from a concentrated solution4 ,when the solution is originally saturated it thus becomes supersaturated1 and deposits these long ciliary crystals on the surface of the growth4 ,when a capsule splits in two under the influence of the internal osmotic pressure1 it may happen that the operculum or upper valve floats away in the liquid4 ,we thus obtain a free swimming organism1 a transparent bell-like form with an undulating fringe1 like a ,medusa4 ,illustration3 ,,fig4 #ed4--;,capsular osmotic growth1 the two valves separated showing the colloidal contents4 ,frequently a single seed or stock will give rise to a whole series of osmotic growths4 ,a vesicle is first produced1 and then a contraction appears around the vesicle1 and this contraction increases till a portion of the vesicle is cut off and swims away free like an amoeba4 ,the same phenomenon may be observed with vermiform growths1 a single seed often giving #ada rise in this way to a whole series of amoebiform or vermiform productions4 ,it must be remembered that in an osmotic growth the active growing portion is the gelatinous contents in the interior1 the external visible growth being only a skeleton or shell4 ,we may sometimes succeed in hooking up one of these long vermiform growths1 breaking the calcareous sheath1 and drawing out a long undulating translucid gelatinous cylinder4 ,the outline of this cylinder is so well defined as to make us doubt whether the fine colloidal membrane which separates it clearly from the liquid can have been formed so rapidly1 or if it may not perhaps exist already formed in the interior of its calcareous sheath4 ,illustration3 ,,fig4 #ee4--,microphotograph showing the structure of various osmotic stems4 7,magnified #be diameters47 7a7 ,sodium sulphite4 7b7 ,potassium bichromate4 7c7 ,sodium sulphide4 7d7 ,sodium bisulphite4 ,when a large capsular shell such as we have described bursts1 it expels a part or the whole of its contents as a gelatinous mass which retains the form of the cavity4 ,similarly1 if we suddenly dilute the mother liquor around an osmotic cell1 it bursts by a process of dehiscence1 and projects into the liquid a part of its contents1 which may thus become an independent vesicle4 ,in this way a single osmotic cell may produce a whole series of independent vesicles4 ,it is even possible to rejuvenate an osmotic growth that has become degenerate through age4 ,an osmotic production grows old and dies when it has expended the osmotic force contained in the interior of its capsule4 ,a calcium osmotic growth which has thus become exhausted may be rejuvenated by transferring it to a concentrated solution of calcium chloride4 ,it will absorb this1 and thus be enabled to renew its evolution and growth when put back again into the original mother liquor4 #adb ,the structure of osmotic growths is no less varied than their form4 ,their stems are formed of cells or vesicles juxtaposed1 showing cavities separated by osmotic walls4 ,sometimes the component vesicles have kept their original form1 so that the stem has the appearance of a row of beads4 ,or the cells may be more or less flattened1 the divisions being widely separated4 ,or again1 by the absorption of the divisions1 a tube may be formed1 a veritable vessel or canal in which liquids can circulate4 #adc ,illustration3 ,,fig4 #ef4--,microphotograph showing the structure of osmotic stems4 7,magnified #dj diameters47 ,illustration3 ,,fig4 #eg4--,photograph of an osmotic leaf showing the veins4 ,the foliaceous expansions1 or osmotic leaves1 also present great varieties both of appearance and of structure4 ,the veins may be longitudinal1 fan-shaped1 or penniform4 ,we have occasionally met with leaves having a lined or ruled surface1 giving most beautiful diffraction colours4 ,the usual structure1 however1 is vesicular or cellular1 as in ,fig4 #eh4 ,in photographs we often get the appearance of lacunae1 but all these lacunae are closed cavities1 the appearance being due to the transparency of the cell walls4 ,illustration3 ,,fig4 #eh4--,photomicrograph of an osmotic leaf showing the cellular structure4 ,in conclusion we may say that osmotic growths are formed of an ensemble of closed cavities of various forms1 containing liquids and separated by osmotic membranes1 constituting veritable tissues4 ,this structure offers the closest #add resemblance to that of living organisms4 ,is it possible to doubt that the simple conditions which produce an osmotic growth have frequently been realized during the past ages of the earth8 ,what part has osmotic growth played in the evolution of living forms1 and what traces of its action may we hope to find to-day8 ,osmotic growth gives us fibrous silicates1 phosphatic nodules1 corals1 and madrepores2 it also gives us formations which remind one of the atolls1 calcareous growths rising like a crown out of the water4 ,the geologist may well consider what role osmotic growth may have played in the formation of the various rocks1 siliceous1 calcareous1 barytic1 magnesian1 the fibrous and nodular rocks and atolls4 ,the palaeontologist relies on the different forms found in his rocks to classify his specimens2 from the existence of a shell1 he concludes the presence of life4 ,since1 however1 forms which are apparently organic may be merely the product of osmotic growth1 it is evident that he must reconsider his conclusions4 ,the same may be said of the various forms of coral or of fungoid growths4 ,in the #adf presence of a calcified or silicated fungus we can no longer argue with certainty as to the existence of life1 without taking into consideration the possibility that the specimen in question may be an osmotic production4 ,illustration3 ,,fig4 #ei4--,osmotic growth with nucleated terminal organs4 7,one-third of the natural size47 ,illustration3 ,,fig4 #fj4--;,a group of osmotic plants4 ,whatever our opinion as to its signification1 osmotic growth demands the attention of every mind devoted to the study of nature4 ,it is a marvellous spectacle to see a formless fragment of calcium salt grow into a shell1 a madrepore1 or a fungus1 and this as the result of a simple physical force4 ,why should the study of osmotic growth attract less attention than the formation of crystals1 on which so much time and labour has been bestowed in the past8 99 99 99 99 99 #adg ,,chapter ,,xii ,,the ,,phenomena ,,of ,,life ,,and ,,osmotic ,,productions--,a ,,study ,,in ,,physiogenesis ,it is impossible to define life1 not only because it is complex1 but because it varies in different living beings4 ,the phenomena which constitute the life of a man are far other than those which make up the life of a polyp or a plant2 and in the more simple forms life is so greatly reduced that it is often a matter of difficulty to decide whether a given form belongs to the animal1 vegetable1 or mineral kingdom4 ,considering the impossibility of defining the exact line of demarcation between animate and inanimate matter1 it is astonishing to find so much stress laid on the supposed fundamental difference between vital and non-vital phenomena4 ,there is in fact no sharp division1 no precise limit where inanimate nature ends and life begins2 the transition is gradual and insensible1 for just as a living organism is made of the same substances as the mineral world1 so life is a composite of the same physical and chemical phenomena that we find in the rest of nature4 ,all the supposed attributes of life are found also outside living organisms4 ,life is constituted by the association of physico-chemical phenomena1 their harmonious grouping and succession4 ,harmony is a condition of life4 ,we are quite unable to separate living beings from the other productions of nature by their composition1 since they are formed of the same mineral elements4 ,all the aliments of plants--water1 carbon1 nitrogen1 phosphorus1 sulphur--before their absorption and assimilation belonged to the mineral kingdom4 ,the carbon and the water are transformed into #adh sugar and fat1 the nitrogen and the sulphur into albumen1 and the compounds so formed are then said to belong to the organic world4 ,these organic bodies are returned once again to the mineral world by the action of animals and microbes1 which transform the carbon into carbonates1 and the nitrogen1 sulphur1 and phosphorus into nitrates1 sulphates1 and phosphates4 ,hence life is but a phase in the animation of mineral matter2 all matter may be said to have within itself the essence of life1 potential in the mineral1 actual in the animal and the vegetable4 ,the flux and reflux of matter is alternate and incessant1 from the mineral world to the living1 and back again from the living to the mineral world4 ,at the same time there is a continuous flux of energy4 ,organic matter contains potential energy1 the energy of chemical combination2 and during its passage through the living being it is gradually stripped of this energy and returned to the mineral world4 ,the first step in synthetic biology is the addition of potential energy to matter1 the reduction of an oxide1 the separation of a salt into its radicals1 the production of some endothermic chemical combination4 ,the energy stored up by such processes can be again liberated as heat1 that fire which the ancients with wonderful prescience long ago recognized as the symbol of life4 ,attempts have been made to differentiate a living being by the nature of its chemical combinations1 the so-called organic compounds4 ,it was supposed that life alone could realize these and cause the production of the various substances which form the structure of living beings4 ,of late years1 however1 a large number of these organic substances have been artificially produced in the laboratory1 and the synthetic problems which remain are of the same order as those which have been already solved4 ,as one learns to know the mineral kingdom and the living world more intimately the differences between them disappear4 ,thus a living being was supposed to be characterized by its sensibility1 i4e4 its faculty of reaction against external impressions4 ,but this reaction is a general phenomenon of nature2 there is no action without reaction4 ,neither can the #adi reaction to internal impressions1 immediate or deferred1 be considered as the characteristic of life1 since osmotic growths exhibit a most exquisite sensibility in this direction4 ,since1 then1 the faculty of reaction is a general property of matter1 the characteristics of life in the lower organisms are only three in number1 viz4 nutrition1 growth1 and reproduction by fission or budding4 ,but crystals are also nourished and grow in the water of crystallization4 ,they have moreover a specific form1 and every biologist who wishes to establish a parallel between the phenomena of the living and the mineral world is wont to compare living beings with crystals4 ,crystals1 it is said1 affect regular geometric forms1 salient angles1 and rectilinear edges1 while living beings have rounded forms without any geometric regularity4 ,another supposed distinction is that living beings are nourished by intussusception1 whereas crystals increase by apposition4 ,again1 living beings are said to assimilate and transform the aliment they absorb1 whereas crystals do not transform the matter which is added externally to their structure4 ,another supposed difference is that living things eliminate and discharge their products of combustion1 while the evolution of a crystal is accompanied by no such elimination4 ,finally1 the phenomenon of reproduction is said to be the exclusive characteristic of a living being2 but crystals may also be reproduced and multiplied by the introduction of fragments of crystalline matter into a supersaturated solution4 ,the resemblance between an osmotic growth and a living organism is much closer than that between a living being and a crystal1 there being not only an analogy of form1 but also of structure and of function4 ,in order to find the physical parallel to life1 we must turn to osmosis and osmotic growth rather than to crystals and crystallization4 ,the first and most striking analogy between living beings and osmotic growths is that of form4 ,the morphogenic power of osmosis gives rise to an infinite variety of forms4 ,an osmotic growth1 even at the first sight1 suggests the idea of a living thing4 ,one need only glance at the photographs of osmotic productions to recognize the forms of madrepore1 fungus1 alga1 and shell4 ,it is wonderful that a force capable #aej of such marvellous results should have hitherto been almost entirely neglected4 ,a second analogy between vital and osmotic growths is to be found in their structure1 both being formed by groups of cells or vesicles separated by osmotic membranes4 ,an osmotic stem1 formed by a row of cellular cavities separated by osmotic membranes1 has a great structural resemblance to the knotted stems of bamboos1 reeds1 and the like4 ,the foliaceous expansions of osmotic growths are formed by colonies of cells or vesicles disposed in regular lines1 which may present various patterns of innervation1 parallel1 palmate1 or pennate4 ,many of the lamellar osmotic growths are striped in parallel lines alternately opaque and transparent4 ,the terminal organs have also their enveloping membranes1 their pulp and nucleus1 just like vegetable forms4 ,the analogies of function are no less remarkable than those of form and structure4 ,nutrition is perhaps the most elementary and essential vital phenomenon1 since without nutrition life cannot exist4 ,nutrition consists in the absorption of alimentary substances from the surrounding medium1 the chemical transformation of such substances1 their fixation by intussusception in every part of the organism1 and the ejection of the products of combustion into the surrounding medium4 ,osmotic growths absorb material from the medium in which they grow1 submit it to chemical metamorphosis1 and eject the waste products of the reaction into the surrounding medium4 ,an osmotic growth moreover exercises choice in the selection of the substances which are offered for its consumption1 absorbing some greedily and entirely rejecting others4 ,thus osmotic growths present all the phenomena of nutrition1 the fundamental characteristic of life4 ,in the living organism nutrition results in growth1 development1 and evolution4 ,growth and development also follow the absorption and fixation of aliment by an osmotic production4 ,an osmotic production grows1 its form develops and becomes more complicated1 and its weight increases4 ,an osmotic growth may weigh many hundred times as much as the mineral sown in the solution1 the mother liquor losing a #aea corresponding weight4 ,thus growth1 which has hitherto been considered an essential phenomenon of life1 is also a phenomenon common to all osmotic productions4 ,osmotic growths like living things may be said to have an evolutionary existence1 the analogy holding good down to the smallest detail4 ,in their early youth1 at the beginning of life1 the phenomena of exchange1 of growth1 and of organization are very intense4 ,as they grow older1 these exchanges gradually slow down1 and growth is arrested4 ,with age the exchanges still continue1 but more slowly1 and these then gradually fail and are finally completely arrested4 ,the osmotic growth is dead1 and little by little it decays1 losing its structure and its form4 ,the membranes of an osmotic growth thicken with age1 and thus oppose to the osmotic exchanges a steadily increasing resistance4 ,young osmotic cells appear swollen and turgescent1 whereas old ones become flaccid1 relaxed1 and wrinkled4 ,analogous phenomena are met with in living organisms1 the calcareous infiltration of the vessels representing the thickening and hardening of the osmotic membranes4 ,the plumpness of a child and the turgescence of young cells are but the expression of high osmotic tension1 while relaxation and flaccidity of the tissues in old age betrays the fall of osmotic pressure in the intracellular tissues4 ,circulation of the nutrient fluid may also be observed in an osmotic growth as in a living organism4 ,if we take a calcareous growth with long ramified stems and dilute the mother liquor considerably1 we may see currents of liquid issuing from the summit of the growth--currents which are made visible by the cloudy precipitates which they cause4 ,the same current is also rendered visible in the stems themselves by the motion of the granulations and gas bubbles in the interior of the osmotic cells4 ,it is plain that some such circulation must exist1 for how could a membrane be formed #cj centimetres from the seed if the membranogenous substance did not circulate through the stem8 ,a moment's consideration will show that the propulsion is due to osmotic pressure and not to mere differences of density1 for the liquid #aeb which rises in the stem is a concentrated solution of calcium salt much denser than the mother liquor1 and the current of liquid after rising in the stem may be seen to fall back again through the liquid4 ,illustration3 ,,fig4 #fa4--;,a group of osmotic forms4 ,organization has long been considered as one of the principal characteristics of life1 i4e4 the arrangement of matter so as to produce an animated and evolutionary form accompanied by transformation of energy4 ,but osmotic growths are also organizations endowed with the same faculties1 and the physical mechanism which is at the basis of their formation is the same as that which determines the organization of living matter4 ,the phenomena of osmotic growth show how ordinary mineral matter1 carbonates1 phosphates1 silicates1 nitrates1 and chlorides1 may imitate the forms of animated nature without #aec the intervention of any living organism4 ,ordinary physical forces are quite sufficient to produce forms like those of living beings1 closed cavities containing liquids separated by osmotic membranes1 with tissues similar to those of the vital organs in form1 colour1 evolution1 and function4 ,it is only necessary to glance at the photographs of these osmotic growths to appreciate the wonderful variety of form4 ,the variety of function is not less evident1 and in many instances1 especially with manganese salts1 the difference of function of various regions is marked by differences of colour4 ,when a large osmotic cell projects beyond the mother liquor and grows up into the air1 it is evident that the function of liquid absorption must be localized in the submerged part4 ,in other cases we have a local evolution of gas1 which may be demonstrated by growing a fragment of calcium chloride in a mother liquor composed of the following saturated solutions3-- ,potassium carbonate #gf parts4 ,potassium sulphate #af ,tribasic potassium phosphate #df ,during the whole period of growth there is an abundant liberation of bubbles of gas1 which is accurately limited to a belt around the base of the growth1 and sometimes also to a cap at the summit4 ,since morphological differentiations of different parts is but the result of differences of evolution1 i4e4 of functional differences of the various parts1 we may consider that osmotic growths possess the faculty of organization like living beings4 ,an osmotic growth may be wounded1 and a wound delays its growth and development like a disease or an accident in a living being4 ,a wound in an osmotic production may also become cicatrized and covered with a membrane1 when the growth will recommence exactly as in a living being4 ,an osmotic growth is a transformer of energy4 ,it increases in bulk1 pushing aside the mother liquor1 and thus doing external work4 ,an osmotic growth has a temperature above its medium1 since the chemical reaction of which it is the seat is accompanied by the production of heat4 ,we know #aed but little of the transformation of energy which takes place in an osmotic production1 but we may say with certainty that it is capable of transforming both chemical energy and osmotic energy into heat and mechanical motion4 ,an osmotic production is the arena of complicated chemical phenomena which produce a veritable metabolism4 ,it has long been known that diffusion and osmosis may determine various chemical transformations4 ,h4 ,st4 ,clair ,deville has demonstrated that certain unstable salts are partially decomposed by diffusion4 ,thus during the diffusion of alum1 the sulphate of potash is separated from the sulphate of aluminium4 ,similarly1 when the chloride or acetate of aluminium is caused to diffuse1 the acids become separated from the aluminia4 ,this decomposition is the result of the different resistance which the medium offers to the diffusion of different ions4 ,this difference of resistance may even cause a difference of potential between two media1 similar to the differences of potential in living organisms4 ,frequently also a difference of hydration in the chemical substances on either side of an osmotic membrane will determine a chemical reaction1 which like all other chemical reactions is accompanied by a corresponding transformation of energy4 ,the study of these chemical metamorphoses and the transformations of energy in osmotic growths has opened up a new subject for experimental investigation in the field of organic chemistry4 ,coagulation4--,there is a most remarkable analogy between the phenomena of coagulation as seen in living beings and the phenomena which occur when the liquid in the interior of an osmotic growth comes into contact with the mother liquor4 ,when the sap of a plant or the blood of an animal escapes into the air or water of the surrounding medium1 it coagulates1 i4e4 it changes from a liquid to a gelatinous consistency4 ,in the same way1 when the liquid in the interior of an osmotic growth leaks out into the mother liquor it forms a gelatinous precipitate4 ,this gelatinous precipitation is a physico-chemical phenomenon of the same nature as coagulation4 ,it is by the study of coagulation in liquids less complex than blood that we may hope to elucidate the mechanism of the process1 #aee which is simply a physico-chemical phenomenon exactly analogous to gelatinous precipitation4 ,calcium phosphate is always prone to coagulate2 it has been called the gelatinous phosphate of lime1 and we have already seen how readily tribasic calcium phosphate takes the form of beautiful transparent colloidal membranes which are gelatinous in texture4 ,we may obtain colloidal precipitates exactly analogous to coagulated albumin by mixing a weak solution of chloride of calcium with potassium carbonate or tribasic phosphate4 ,like albumin this precipitate forms flakes1 and is deposited slowly as a gelatinous colloidal mass4 ,like albumin also this calcic solution is coagulated by heat2 a solution of a calcic salt of a volatile acid on heating forms a precipitate which has all the appearance of albumin coagulated by heat4 ,finally1 ,arthus and ,pages have shown that blood does not coagulate when deprived of its calcium salts by the addition of alkaline oxalates1 fluorides1 or citrates1 and that the blood thus treated recovers its coagulability on the addition of a soluble salt of calcium4 ,the coagulation of milk is also a calcium salt precipitation4 ,coagulation therefore would seem to be merely the colloidal precipitation of a salt of calcium4 ,diffusion and osmosis are the elementary phenomena of life4 ,all vital phenomena result from the contact of two colloidal solutions1 or of two liquids separated by an osmotic membrane4 ,hence the study of the physics of diffusion and osmosis is the very basis of synthetic biology4 ,a living being exhibits two sorts of movements1 those which are the result of stimulus from without1 and those which are determined by an excitation arising from within4 ,in the higher animals the stimulus or exciting energy coming from the entourage may be infinitely small when compared with the amount of energy transformed4 ,moreover1 the response to an identical excitation may so vary as to give to these different responses an appearance of spontaneity4 ,there is in reality no spontaneity1 since the difference in response is governed by previous external impressions which have left their record on the machinery4 ,there is in fact no such thing as a spontaneous action1 since every action of a living #aef being has as its ultimate cause a stimulus or excitation coming from without4 ,the movements of the second category are also conditioned by an excitation1 but the stimulus comes from within the organism4 ,these movements consist principally of changes of nutrition1 or movements of the circulation and respiration2 they are rhythmic in character and are probably produced by the same chemico-physical causes which determine rhythmic movements outside the living body4 ,just in the same way osmotic growths present two sorts of movements1 external movements and those which are connected with their nutrition4 ,a free osmotic growth swimming in the mother liquor will alter its position and form under the influence of the slightest exterior excitation or vibration4 ,it responds to every variation of temperature1 or to a slight difference of concentration produced by adding a single drop of water1 and reacts to every exterior influence by displacement or deformation4 ,an osmotic growth also shows indications of movements which are connected with its nutrition1 and these movements are rhythmic1 like those of respiration or circulation in a living organism4 ,the growth of an osmotic production shows itself not as a continuous process but periodically4 ,the water traverses the membrane1 raises the pressure1 and distends the cell2 at first the cell wall resists by reason of its elasticity1 it then suddenly relaxes1 yielding to the osmotic pressure and bulging out at a thinner spot on the surface2 the internal pressure falls suddenly1 and there is a pause in the growth4 ,this rhythmic growth may be best observed by sowing in a solution of a tribasic alkaline phosphate1 pellets composed of powdered calcium chloride moistened with glycerine1 to which has been added #a per cent4 of monobasic calcium phosphate4 ,the experiment is so arranged as to bend or incline the growing stems which shoot out from these grains4 ,this may be done by carefully pouring above the mother liquor a layer of water1 or a less concentrated solution4 ,as the internal osmotic pressure rises1 the drooping extremity of the twig will become turgescent and gradually lift itself #aeg up1 and then suddenly fall again for several millimetres4 ,we have frequently watched this rhythmic movement for an hour or more--a slow gradual elevation of the extremity of the twig and a rapid fall recurring every four seconds or so4 ,it may be objected that the substance of an osmotic growth is continually undergoing change1 whereas a living organism transforms into its own substance the extraneous matter which it borrows from its environment4 ,the distinction1 however1 is only an apparent one4 ,the substance of a living being is also continually undergoing chemical change2 it does not remain the same for a single instant4 ,we see an evidence of this change in the evolution of age2 the substance of the adult is not that of the infant4 ,in some living organisms such as insects1 especially the ephemeridae who have but a brief existence1 this change of substance is even more rapid than that in an osmotic growth4 ,it has been objected that osmotic productions cannot be compared with living organisms since they contain no albuminoid matter4 ,this is to consider life as a substance1 and to confound the synthesis of life with that of albumin4 ,if albumin is ever produced by synthesis in the laboratory it will probably be dead albumin4 ,all living organisms contain albumin2 this is probably due to the fact that albuminoid matter is particularly adapted for the formation of osmotic membranes4 ,our osmotic productions are composed of the same elements as those which constitute living beings2 an osmotic growth obtained by sowing calcium nitrate in a solution of potassium carbonate with sodium phosphate and sulphate contains all the principal elements of a living organism1 viz4 carbon1 oxygen1 hydrogen1 nitrogen1 sulphur1 and phosphorus4 ,the whole of the vegetable world is produced by the osmotic growth of mineral substances1 if we except the small amount of organic matter contained in the seeds4 ,the most important problem of synthetic biology is not so much the synthesis of the albuminoids as the reduction of carbonic acid4 ,in nature this reduction is accomplished by the radiant energy of the sun1 by the agency of the catalytic action of chlorophyll4 #aeh ,the physico-chemical study of osmotic growth is as yet hardly begun2 we have but indicated the method1 the way is open1 and the problems awaiting solution are legion4 ,only work and ever more work and workers are required4 ,experiments should be made with substances which are chemically unstable like the albuminoids1 substances which readily combine and dissociate again1 alternately absorbing and giving up the potential energy which is the essence of life4 ,experiments should also be made with substances which readily unite or decompose under the influence of water1 since hydration and hydrolysis appear to be the dominant mechanism in all vital reaction1 as they undoubtedly are in osmotic growth1 which consists of an increase of hydration on one side of an osmotic membrane and a diminution on the other side4 ,life is not a substance but a mechanical phenomenon2 it is a dynamic and kinetic transference of energy determined by physico-chemical reactions2 and the whole trend of modern research leads to the belief that these reactions are of the same nature as those met with in the organic world4 ,it is the grouping of physical reactions and their mode of association and succession1 their harmony in fact1 which constitutes life4 ,the problem we have to solve in the synthesis of life is the proper attuning and harmonizing of these physical phenomena1 as they exist in living beings1 and there should be no absolute impossibility in our some day realizing this harmony in whole or in part4 ,albert ,gaudry says3 ,i cannot conceive why in determining the connecting links of the animal world the fact that an organic body is formed of such and such elements should be of greater importance than the manner in which these elements are grouped4 ,descartes regarded extension as the essential property of an organized being2 he supposed it to be inert of itself1 and that it had the ,deity for its motive force4 ,to-day the hypothesis of ,descartes has given way to that of ,leibnitz1 who regards force as the essential property of the living being1 the visible and tangible matter being only of secondary importance4 ,if we regard the living being as a force1 this force is able to aggregate matter under such and such a form1 #aei with such or such a structure1 and such or such a chemical essence4 ,it does not seem that the classification depending on differences of substance are any more important than those which depend on differences of form4 ,the biological interest of osmotic productions is quite independent of the chemical nature of the substances which enter into their growth4 ,all substances which produce osmotic membranes by the contact of their solutions exhibit phenomena analogous to those of nutrition4 ,osmotic morphogenesis is a physical phenomenon resulting from the contact of the most diverse substances4 ,it has given us our first glimpse of the manner in which a living being may be supposed to have been formed according to the ordinary physical laws of nature4 ,we cannot at present produce osmotic growths with all the combinations found in living beings1 but that is only because chemistry still lags far behind physics in the synthesis of organic forms4 ,we are often told not to force the analogy4 ,but error is equally produced by the exaggeration of unimportant differences4 ,we have already seen that nutrition1 absorption1 transformation1 and excitation are not the characteristics of living organisms alone2 nor is reaction to external impressions the appanage only of animate beings4 ,to insist on the resemblance between an osmotic production and a living being is not to force an analogy but to demonstrate a fact4 ,let us briefly recapitulate4 ,an osmotic growth has an evolutionary existence2 it is nourished by osmosis and intussusception2 it exercises a selective choice on the substances offered to it2 it changes the chemical constitution of its nutriment before assimilating it4 ,like a living thing it ejects into its environment the waste products of its function4 ,moreover1 it grows and develops structures like those of living organisms1 and it is sensitive to many exterior changes1 which influence its form and development4 ,but these very phenomena--nutrition1 assimilation1 sensibility1 growth1 and organization--are generally asserted to be the sole characteristics of life4 99 99 99 99 99 #afj ,,chapter ,,xiii ,,evolution ,,and ,,spontaneous ,,generation ,by many biologists1 even at the present day1 the origin and evolution of living beings is considered to be outside the domain of natural phenomena1 and hence beyond the reach of experimental research4 ,the change in our views on this subject is due to a ,frenchman1 ,jean ,lamarck1 who was the true originator of the scientific doctrine of evolution4 ,at a time when the miraculous origin of every living being was regarded as an unchangeable verity1 and was defended like a sacred dogma1 ,lamarck boldly formulated his theory of evolution1 with all its attendent consequences1 from spontaneous generation to the genealogy of man4 ,in his ,philosophie ,zoologique1 which appeared in #ahji1 ,lamarck put forth his claim to regard all the phenomena of life1 of living beings1 and of man himself as pertaining to the domain of natural phenomena4 ,according to him1 all bodies which are met with in nature1 organic and inorganic alike1 are subject to the same laws4 ,life is a physical phenomenon1 and all the processes of life are due to mechanical causes1 either physical or chemical4 ,he writes3 ,a leur source le physique et le moral ne sont sans doute qu'une seule et meme chose4 ,il faut rechercher dans la consideration de l'organisation les causes memes de la vie4 ,in the intellectual evolution of the human mind perhaps no advance has been more important than that of ,lamarck--the conquest of the domain of life by human intelligence4 ,in conformity with the true scientific method1 he founds his doctrine on the facts and phenomena of nature4 ,i confine myself1 he says1 within the bounds of a simple contemplation #afa of nature4 ,it was this observation of the gradual perfecting of living organisms from the simplest to the most complicated that inspired ,lamarck with the idea of evolution and transformation4 ,how1 he says1 can we help searching for the cause of such wonderful results8 ,are we not compelled to admit that nature has produced successively bodies endowed with life1 proceeding from the simplest to the most complex8 ,the various products of nature have been divided into classes1 genera1 and species1 simply to facilitate their study4 ,modern research tends to show that there is no definite line of demarcation even between the animal1 vegetable1 and mineral kingdoms4 ,all our classification is artificial1 and the passage from one division to another is gradual and insensible4 ,lamarck expresses this idea very clearly3 ,we must remember that classes1 orders1 and families1 and all such nomenclature1 are methods of our own invention4 ,in nature there are no such things as classes or orders or families1 but only individuals4 ,as we become better acquainted with the productions of nature1 and as the number of specimens in our collections increases1 we see the intervals between the classes gradually fill up1 and the lines of separation become effaced4 ,lamarck also raises his voice against the supposed immutability of species4 ,species have only a relative constancy1 depending on the circumstances of the individuals4 ,the individuals of a given species perpetuate themselves without variation only so long as there is no variation in the circumstances which influence their existence4 ,numberless facts prove that when an individual of a given species changes its locality1 it is subjected to a number of influences which little by little alter1 not only the consistency and proportions of its parts1 but also its form1 its faculty1 and even its organization2 so that in time every part will participate in the mutations which it has undergone4 ,lamarck also clearly affirms the fact of spontaneous generation4 ,i hope to prove1 he says1 that nature possesses means and faculties for the production of all the forms which we so much admire4 ,rudimentary animals and plants have #afb been formed1 and are still being formed to-day1 by spontaneous generation4 ,lamarck himself gives a resume of his doctrine in the following six propositions3-- #a4 ,all the organized bodies of our globe are veritable productions of ,nature1 which she has successively formed during the lapse of ages4 #b4 ,nature began1 and still recommences day by day1 with the production of the simplest organic forms4 ,these so-called spontaneous generations are her direct work1 the first sketches as it were of organization4 #c4 ,the first sketches of an animal or a vegetable growth being begun under favourable conditions1 the faculties of commencing life and of organic movement thus established have gradually developed little by little the various parts and organs1 which in process of time have become diversified4 #d4 ,the faculty of growth is inherent in every part of an organized body2 it is the primary effect of life4 ,this faculty of growth has given rise to the various modes of multiplication and regeneration of the individual1 and by its means any progress which may have been acquired in the composition and forms of the organism has been preserved4 #e4 ,all living things which exist at the present day have been successively formed by this means1 aided by a long lapse of time1 by favourable conditions1 and by the changes on the surface of the globe--in a word1 by the power which new situations and new habits have of modifying the organs of a body which is endowed with life4 #f4 ,since all living things have undergone more or less change in their organization1 the species which have been thus insensibly and successively produced can have but a relative constancy1 and can be of no very great antiquity4 ,the admirable work of ,lamarck was absolutely neglected in ,france1 where it was treated as unworthy even of consideration4 ,this neglect profoundly afflicted ,lamarck1 who gradually sank a victim to the opposition of his contemporaries4 ,he left1 however1 one disciple1 ,etienne ,jeoffroy ,st4 #afc ,hilaire1 but he too was soon reduced to silence under the weight of authority of his adversaries4 ,illustration3 ,,fig4 #fb4--,osmotic vegetation4 ,before the doctrine of evolution could live and take its proper place1 it had to be reborn in ,england--the country of liberty4 ,this resuscitation was due to ,darwin1 who added to it his illuminating doctrine of natural selection4 ,but apart from this and a perfecting of its various details1 ,lamarck had already formulated the doctrine of evolution with perfect precision4 ,lamarck's work was still-born1 whereas that of ,darwin lived and grew to its full development4 ,this was due1 not to any imperfection or insufficiency in ,lamarck's work1 but #afd to the milieu into which it was born4 ,it was the environment that stifled the offspring of ,lamarck4 ,in #ahfh1 ,ernest ,haeckel speaks of the genius of ,lamarck in these words3 ,the chief of the natural philosophers of ,france is ,jean ,lamarck1 who takes his place beside ,goethe and ,darwin in the history of evolution4 ,to him belongs the imperishable glory of being the first to formulate the theory of descent1 and of founding the philosophy of nature on the solid basis of biology1 and adds1 ,there is no country in ,europe where ,darwin's doctrine has had so little influence as in ,france4 ,haeckel has but done tardy justice in his discovery of and testimony to the genius of ,lamarck4 ,the spirit of opposition does not seem to have much changed in ,france since ,lamarck's time4 ,in #aijg the ,academie des ,sciences de ,paris excluded from its ,comptes ,rendus the report of my researches on diffusion and osmosis1 because it raised the question of spontaneous generation4 ,the majority of scientists seem to consider that the question of spontaneous generation was definitely settled once for all when ,pasteur's experiments showed that a sterilized liquid1 kept in a closed tube1 remained sterile4 ,without the idea of spontaneous generation and a physical theory of life1 the doctrine of evolution is a mutilated hypothesis without unity or cohesion4 ,on this point ,lamarck speaks most clearly3 ,although it is customary when one speaks of the members of the animal or vegetable kingdom to call them products of nature1 it appears that no definite conception is attached to the expression4 ,our preconceived notions hinder us from recognising the fact that ,nature herself possesses all the faculties and all the means of producing living beings in any variety4 ,she is able to vary1 very slowly but without cessation1 all the different races and all the different forms of life1 and to maintain the general order which we see in all her works4 ,the doctrine of ,lamarck is frequently misinterpreted4 ,we often hear it expressed as ,function makes the organ1 or even ,function creates the organ4 ,this is equivalent to saying1 ,life makes the living being1 which is incomprehensible1 #afe making of function a sort of immaterial and independent entity which constructs a material organ in order to lodge within it4 ,no such idea is to be found in all the works of ,lamarck4 ,he formulates his law in the following terms3 ,in every animal which is still undergoing development1 the frequent and sustained use of any one organ increases its size and power1 whereas the constant neglect of the use of such organ weakens and deteriorates it1 so that it finally disappears4 ,in his expression of this law ,lamarck insists on the fact that organization precedes function4 ,he affirms only that function1 i4e4 action and reaction1 modifies the organ2 or1 in other words1 that organisms are modelled by the action of exterior forces acting upon them4 ,it is in this sense only that function may be said to make an organ1 but this mode of expression should be avoided1 as it is apt to be misunderstood4 ,astronomy teaches us that our globe was detached from the sun in an incandescent state1 and geology asserts that this earth has passed through a period of long ages when its temperature was incompatible with the existence of life4 ,it was only with the cooling of the earth crust that it was possible for living beings to make their appearance4 ,hence they must of necessity have been produced spontaneously from terrestrial material under the influences of chemical and physical forces4 ,this opinion imposes itself on all who reflect and judge freely4 ,in the same way the doctrine of evolution necessitates as a corollary the doctrine of spontaneous generation4 ,the doctrine of evolution should reconstitute every link in the chain of beings from the simplest to the most complicated2 it cannot afford to leave out the most important of all1 viz4 the missing link between the inorganic and the organic kingdoms4 ,if there is a chain1 it must be continuous in all its parts1 there can be no solution of continuity4 ,evolutionists like ,lamarck and ,haeckel admit spontaneous generation1 not as the most probable1 but as the only possible explanation of the phenomenon of life4 ,lamarck shows us the apparition of living things at a certain epoch of the earth's evolution1 and the gradual #aff development of more complicated forms as the conditions changed on the surface of the globe4 ,darwin shows how heredity and natural selection tend to accentuate the variations which are favourable to existence4 ,haeckel demonstrates the parallelism between ontogenesis and philogenesis--between the successive forms in the evolution of the embryo and the successive forms of the individual in the evolution of a race4 ,these are great and admirable conquests of the human intelligence1 they have demonstrated the first appearance and the progressive evolution of living beings2 it now only remains for us to explain them4 ,illustration3 ,,fig4 #fc4--,marine forms of osmotic growth4 ,the doctrine of evolution1 while enforcing the fact of spontaneous generation and progressive evolution1 gives us no hint as to the physical mechanism of such generation4 ,it does not tell us by what forces1 or according to what laws1 the simpler forms of life have been produced1 or in what manner differences of environment have acted in order to modify them4 ,the doctrine asserts the simultaneous variations in organic forms and in the physical influences which produce them1 but says #afg nothing as to their mode of action4 ,the ,darwinian theory shows how acquired variations are transmitted and accentuated by natural selection1 but it says nothing as to how these variations may be acquired4 ,in the same way we are in entire ignorance as to the physical mechanism of ontogenetic development1 the evolution of the embryo4 ,the morphogenic action of diffusion produces osmotic growths of extreme variety4 ,most of these forms recall those of living things--shells1 fungi1 corals1 and algae4 ,the analogy of function is quite as close as the resemblance of form4 ,the study of osmosis1 however1 is as yet in its infancy1 and osmotic productions vary with the physical conditions of chemical constitution1 temperature1 concentration1 and the like4 ,the study of the organizing action of osmosis on organic material has as yet been hardly attempted4 ,osmosis produces growths of great complexity1 much more complicated indeed than the more simple forms of living organisms4 ,this marvellous complexity of an osmotic growth may be compared with another fact1 the ontogenetic development of the ovum1 a single cell which under favourable conditions of environment may evolve into a most complicated organism4 ,these considerations lead to the belief that the beginning of life has not been the production of a simple primitive form from which all others are descended1 but that a number of such primitive forms may have been produced1 forms which by a rapid physical development attained a high degree of complexity4 ,osmotic morphogenesis shows us that the ordinary physical forces have in fact a power of organization infinitely greater than has been hitherto supposed by the boldest imagination4 ,when we consider the ignorance in which we still remain as to the phenomena which pass before our very eyes1 how can we expect to understand those which occurred in past ages1 when the physical and chemical conditions were so immensely different from those which obtain in our own time8 ,what do we know even now of the physical and chemical phenomena which take place in the unfathomed depths of the ocean1 where for aught we know even at the present time the same #afh process may be going on--the genesis of life1 and the emergence of living beings out of the inanimate mineral world8 ,even now1 says ,albert ,gaudry1 polyps and oceanic animalculae are building up vast coral reefs and rocks4 ,the oxygen and hydrogen which existed once was water1 the oxygen and nitrogen which once made air1 the carbon1 the phosphorus1 the silica and the lime which once were solid rock1 now form the substance of living beings4 ,the silica is deposited in the skeleton of a sponge or a radiolaria1 the shell of a foraminifera or the carapace of a crustacean1 or unites with phosphorus to form the bones of a vertebrate4 ,a very tumult of life has succeeded to the primitive silence of inert matter4 ,life has invaded the earth1 and we see on all sides the inanimate mineral kingdom being changed into a living world4 ,the admission that life may have appeared on the earth under the influence of natural forces and according to physical laws and conditions different from those of the present era throws a vivid light on the study of biogenesis1 spontaneous generation1 and evolution4 ,the means of research are now indicated1 and we have only to study the documents already in our possession in order to know the conditions which obtained when life first appeared on the globe4 ,we must endeavour to reproduce these conditions and to study their effects4 ,since all living beings are formed of the same elements as those of the mineral world1 the term organic as applied to combinations can only be used in order to emphasize the complexity of their constitution4 ,it was formerly believed that these organic combinations were the result of life1 and could not be reproduced except by living organisms4 ,to-day many of these organic substances are produced in the laboratory from inorganic materials4 ,in the past history of the globe it is easy to imagine conditions which would facilitate the synthesis of organic substances without the interposition of life4 ,at the temperature of the electric furnace1 which was that of the earth at an early period of its evolution1 chemical combinations are possible quite other than those obtaining under the present conditions of temperature and pressure4 ,at the higher temperature of the early #afi geological era1 silicides1 carbides1 phosphides1 and nitrides were formed in stable combinations instead of the oxides1 silicates1 carbonates1 phosphates1 and nitrates of the present time4 ,these combinations existed on the earth at a time when the conditions of temperature precluded the existence of water in a liquid state4 ,as the temperature cooled1 and the water vapour became condensed1 it entered into chemical combination with the various rocks1 producing organic compounds like acetylene1 which results from the action of water on calcium carbide4 ,h4 ,lenicque has developed a theory as to the formation of various rocks under these conditions1 which he communicated in #aijc to the ,french ,society of ,civil ,engineers4 ,the chemical evolution of the globe has undergone great changes as the temperature gradually fell and the constitution of its crust altered4 ,as long as the temperature was higher than that at which water can exist1 all chemical reactions must have taken place between anhydric substances1 elements and salts in a state of fusion4 ,these conditions are very different from those of the present-day chemistry1 which is the chemistry of aqueous solutions4 ,we may hope to be able to reproduce the earlier conditions by the experimental study of anhydric substances in a state of fusion4 ,at a later period1 that of the primary and secondary rocks1 there was a uniform and constant temperature of about #dj;deg ,c4 ,the atmosphere was charged with water vapour1 and all the conditions were present for the production of storms and tempests4 ,the atmosphere during long ages must have been the seat of formidable and incessant electric discharges2 these discharges are the most powerful of all physical agents of chemical synthesis1 and will cause nitrogen to combine directly to form various compounds--nitrates1 cyanides1 and ammonia4 ,carbonic acid would also be present in abundance and would enter into combination with these nitrogenous compounds4 ,in this way we may imagine that compounds were formed which by some process of physical synthesis subsequently gave rise to vast quantities of albuminoid matter4 ,at that time the seas and oceans contained all those substances which have #agj since been fixed by the metamorphism of the primitive rocks1 or deposited in the sedimentary strata4 ,most of the elements in our minerals were formerly in a state of solution in these primeval seas1 which contained carbonates1 silicates1 and soluble phosphates in great abundance4 ,as the crust gradually cooled1 the terrestrial atmosphere of necessity altered in composition1 and the slow evolution of the atmosphere no doubt also exercised an influence on the development of living beings4 ,palaeontology teaches us that the earliest living organism appeared in the sea4 ,the most ancient of living things1 those of the primary ages1 which were of greater duration than all other ages put together1 were all aquatic4 ,we find moreover that every living organism consists of liquids1 solutions of crystalloids and colloids separated by osmotic membranes2 and it is significant that the ocean1 that vast laboratory of life1 is also a solution of crystalloids and colloids4 ,it is evident1 then1 that we must look to the study of solutions if we would hope to discover the nature and origin of life4 ,life is an ensemble of functions and of energy-transformations1 an ensemble which is conditioned by the form1 the structure1 and the composition of the living being4 ,life1 therefore1 may be said to be conditioned by form1 i4e4 the external1 internal1 and molecular forms of the living being4 ,all living things consist of closed cavities1 which are limited by osmotic membranes1 and filled with solutions of crystalloids and colloids4 ,the study of synthetic biology is therefore the study of the physical forces and conditions which can produce cavities surrounded by osmotic membranes1 which can associate and group such cavities1 and differentiate and specialize their functions4 ,such forces are precisely those which produce osmotic growths1 having the forms and exhibiting many of the functions of living beings4 ,of all the theories as to the origin of life1 that which attributes it to osmosis and looks on the earliest living beings as products of osmotic growths is the most probable and the most satisfying to the reason4 ,illustration3 ,,fig4 #fd4--,osmotic shells and corals4 ,we have already seen that the seas of the primary and #aga secondary ages presented in a high degree the particular conditions favourable for the production of osmotic growths4 ,during these long ages an exuberant growth of osmotic vegetation must have been produced in these primeval seas4 ,all the substances which were capable of producing osmotic membranes by mutual contact sprang into growth1--the soluble salts of calcium1 carbonates1 phosphates1 silicates1 albuminoid matter1 became organized as osmotic productions1--were born1 developed1 evolved1 dissociated1 and died4 ,millions of ephemeral forms must have succeeded one another in the natural evolution of that age1 when the living world was represented by matter thus organized by osmosis4 ,the experimental study of osmotic morphogeny adds its weight of evidence in the same direction4 ,when we see under our own eyes the cells of calcium become organized1 develop and grow in close imitation of the forms of life1 we cannot doubt that such a transformation has often occurred in the past history of our planet1 and the conviction becomes irresistible #agb that osmosis has played a predominant role in the history of our earth and its inhabitants4 ,it is a matter of astonishment that the scientist has taken no notice of the active part which osmosis has played in the evolution of our earth4 ,on the effects of this most important physical phenomenon science has hitherto remained entirely mute4 ,printed by ,,morrison ,,gibb ,,limited1 ,edinburgh 99 99 99 99 99 ,corrections made to printed original4 ,page #dg4 into one where its osmotic pressure is low3 'into on' in original4 ,page #ij4 the achromatin spindle in karyokinesis43 'karineyoksis' in original4 ,page #abj4 ,the researches of ,famintzin3 ',famitzin' in original1 inconsistent with spelling #b paragraphs earlier4 ,page #ada4 ,similarly1 if we suddenly dilute3 ',simiarly' in original4 ,page #aec4 which is accurately limited3 'acurately' in original4 ,page #aeh4 this force is able to aggregate matter3 'this orce' in original4