reproduce the characters of its parents and indeed of its ancestors, but if we remember that the great law of all living matter is that the child is not a separate individual, but a part of the living body of the parent, up to a certain date, when it assumes a separate existence, then we can comprehend how living beings inherit ancestral characters, for they are parts of one continuous series in which not a single break has existed or can ever take place. Just as the wave-form over a pebble in a stream remains constant, though the particles of water which compose it are ever changing, so the wave-form of life, which is heredity, remains constant, though the bodies which exhibit it are continually changing. Mr. Tylor's paper was illustrated by a large number of diagrams.

new

Royal Microscopical Society, March 10.-Dr. Beale, F.R.S., president, in the chair. Fifteen gentlemen were nominated or elected Fellows. Mr. Beck exhibited an improved form of microscope with swinging sub-stage; Mr. Mayall traverse lens, by Mr. Tolles; Mr. Dunning a new form of turntable; Dr. H. Gibbes a homogeneous immersion objective for use with the binocular; and Mr. Crisp Klönne and Müller's demonstration microscope and a specimen of micrometric ruling by Prof. Rogers, of Harvard, U.S.--Mr. James Smith described his method of illumination for high powers.-The following papers were read:-On a sponge parasitic within Carpenteria raphidodendron, by Prof. Martin Duncan, F.R.S.-On a petrographical microscope, by M. Nachets.-On double and treble staining of animal tissues, by Dr. H. Gibbes.-On Podophyra quadripartita, by Mr. Badcock.

Institution of Civil Engineers, March 23.-Mr. W. H. Barlow, F.R.S., president, in the chair.-The paper read was on explosive agents applied to industrial purposes, by Prof. Abel, C.B., F.R.S.

EDINBURGH

Royal Society, March 15.-Lord Moncrieff, president, in the chair. By request of the Council, Lieut. Conder, of the Royal Engineers, gave an interesting and detailed lecture on the topography of Jerusalem.-Dr. James Geikie presented a communication on the geology of the Farö Islands, which he had visited last summer in company with Mr. Amund Hellend, of Christiania. In the absence of the author, the paper was read by Prof. Geikie. It was divided into two portions, the first treating of the more purely geological characteristics of the islands, which consist mainly of miocene volcanic formations intermingled with coal and clay dep sits and attaining a thickness of from 10,000 to 12,000 feet; and the second part bearing particularly upon the evidences of glacier action. There were all the indications of prolonged glaciation, striæ, moraines, boulder-clay, &c. ; but there was no evidence that this action was the result of a great ice-drift from the north. Everything indeed proved the glaciation to have been purely local.-Prof. Tait communicated a note on the colouring of maps. This he reduced to the problem of so lettering by the fewest possible symbols a number of points in a plane which have been joined two and two by non-intersecting lines so as to form three-sided areas, that no two connected points shall have the same name. PARIS

Academy of Sciences, March 29.-M. Ed. Becquerel in the chair. The following papers were read :-Application of the theory of sines of superior orders to the integration of differential linear equations, by M. Villarceau.-On the determination of high temperatures, by MM. Sainte-Claire Deville and Troost. They describe an improved form of apparatus they used in 1863 (primarily for determining the expansion of porcelain) now simplified by use of a Sprengel trompe, by means of which may be removed and measured, whenever desirable, the thermometric matter (nitrogen) contained in the porcelain reservoir, and the temperature be calculated.-On the hypergeometric series of two variables, and on simultaneous differential linear equations with partial derivatives, by M. Appell.-On a class of functions of several variables drawn from inversion of integrals of solutions of differential linear equations, the coefficients of which are rational functions, by M. Fuchs.-On the manner in which frictions come into action in a fluid which departs from the state of rest, and on their effect in preventing the existence of a func tion of velocities, by M. Boussinesq.-Memoir on integrations relative to the equilibrium of elasticity, by M. Mathieu.-Researches on diffusion, by M. Joulin. This first portion relates to condensation of various gases by porous bodies (charcoal, dry

or saturated with liquid), the pressure being varied from a few centimetres to 4 atm., and the temperature from 0 to 100°. The absorbent was put in a glass tube which communicated (through tubes with cocks) with a manometric reservoir and a mercury pump. Inter alia, the saturation of dry charcoal with oxygen, nitrogen, or hydrogen is instantaneous, but with carbonic acid slow. Saturation with gaseous mixtures is slower than that with each of the constituent gases. Charcoal soaked with alcohol condenses much less than if soaked with water, and is saturated with gas much more slowly.-On a new property of vanadates, by M. Hautefeuille. Vanadates fused in contact with air rapidly take up a constant quantity of oxygen (bi-vanadate of lithia absorbs in a few minutes more than eight times its volume of this gas at a dark red, and liberates this gas at about 600° during crystallisation). Vanadates liberate in vacuo, in passing from the vitreous to the crystalline state, quantities of oxygen variable with the proportions of acid and base, and the nature of the base. This has a bearing on determination of equivalents. -On some properties of mixtures of cyanide of methyl with ordinary alcohol and with methylic alcohol, by MM. Vincent and Delachanal. The topics treated are the boiling points and densities of the mixtures, and a rational method of separating cyanide of methyl from ordinary alcohol.-Experiments showing that the anesthesia due to certain lesions of the cerebro-rachidian centre may be replaced by hyperesthesia under the influence of another lesion of that centre, by M. Brown-Sequard. Among other conclusions, the theory that the conductors of sensitive impressions of the limbs intercross in the spinal cord must be rejected; and one lateral half of the base of the brain may suffice for the transmission of sensitive impressions from both sides of the body.-Reflex effects of ligature of one pneumogastric on the heart after section of the opposite pneumogastric, by M. FrançoisFranck. In this a retardation or arrest of the heart occurs, almost as notable as if the cut nerve had been intact; this effect is shown to be reflex. He studied the phenomenon in relation to time, with what he calls a nevrotome à signal electrique.-Contribution to the study of the transmission of tuberculosis, by M. Toussaint. From experiments on pigs he infers that where tuberculosis occurs in those animals it is analogous to galloping consumption in man. The bovine species, on the other hand, which have tuberculosis much more often, have most often the chronic variety. Hence young pigs from tubercular parents soon die, and in adults which becozie tubercular the quick progress of the affection prevents reproduction. The facts also prove that tuberculosis is transmitted with the greatest facility (1) by ingestion of tubercular matters, (2) by heredity or lactation, (3) by inoculation with tubercular matter or blood, (4) by simple cohabitation.-On a mode of treatment of certain infantile cases of deafness or deaf-mutism, by M. Boucheron. The cases referred to are those arising from naso. pharyngeal catarrh, causing the mucus of the Eustachian tube to swell and stop the passage, the stirrup bone, ere long, being, through pressure of external air on the tympanum, made to press strongly on the liquid of the labyrinth, injuring the acoustic nerve. M. Boucheron chloroformises the child and practises catheterism, insufflation of air, and pharyngeal cauterisation with a brush dipped in iodine solution.

THURSDAY, APRIL 15, 1880

DOES CHLOROPHYLL DECOMPOSE CARBONIC

T

ACID?

'HE recent memoirs of Pringsheim, noticed in NATURE, vol. xxi. p. 85, by Mr. Vines ("Untersuchungen über das Chlorophyll," July and November, 1879) suggest very serious doubts as to the correctness of an inference which has crept, without the explicit consent of botanical physiologists, into the position of a fundamental doctrine of biological science. The recent excellent article in NATURE on "Vegetation under Electric Light," together with the discussion which took place at the Royal Society when Mr. Siemens's paper describing his experiments on plants under the influence of the electric light was read, tend still further to make it desirable to examine critically the claims which the inference alluded to has on our adhesion.

The inference in question is this, that the substance known as chlorophyll has the property of decomposing carbonic acid so as to fix the carbon and liberate a portion of the oxygen of that acid when in the presence of sun light. Accordingly it has been said that "Chlorophyll is the hand wherewith the organic world lays hold of the carbon of the inorganic world."

Vegetable physiologists are, however, careful not to commit themselves to such an assertion with regard to chlorophyll itself. The chlorophyll-grains or corpuscles are particles of protoplasm impregnated with chlorophyll much in the same way as the blood corpuscles and other tissues of animals are impregnated with hæmoglobin. It is one thing to attribute the decomposition of carbonic acid to "cells containing chlorophyll," or even to "chlorophyll corpuscles," and another thing to pass from such a wide statement to the definite ascription of the CO-decomposing property to the green-coloured substance chlorophyll.

It is perfectly true that by the method of concomitant variation we are led to a conclusion favourable to the importance of chlorophyll in this function. It is only by plants (or animals) containing chlorophyll and only in those parts of plants containing it that CO2 is decomposed and oxygen liberated. Further, it appears that wherever chlorophyll is present in a living organism (even an animal) exposed to sunlight, the decomposition of CO2 takes place. But whilst we are thus justified in connecting chlorophyll with the decomposition in question, any conclusion as to its sole efficiency, and accordingly any notion of a specific chemical activity on its part, is forbidden by two important facts: firstly, that living protoplasm is always present in intimate association with the chlorophyll when the decomposition of CO, is effected (forming the bulk of the chlorophyll-corpuscle); and secondly, that chlorophyll extracted from the chlorophyllcorpuscle and put to the test in the absence of protoplasm has hitherto not been shown to possess the power of effecting the specific decomposition sometimes attributed

to it.

Very usually blood-red and leaf-green are placed side by side as complementary, not only in colour, but in function, the one active in oxidation and the special property of the animal, the other active in deoxidation VOL. XXI.-No. 546

and the special property of the plant. The pleasing agreement in difference which these two bodies apparently present has, no doubt, a real basis in fact, but the actual analogies between them have very possibly tempted the speculative biologist a little too far. Both present remarkable and characteristic absorption spectra, both contain iron, both are diffused in the living albuminoid substance of organisms, the one of plants, the other of animals. Nevertheless a most important fact is true of hæmoglobin, which we have not ground for asserting with regard to chlorophyll, namely, that it can be extracted from the albuminoid substance with which it is associated, and then, when in a pure crystalline state, can be made to exhibit its peculiar property of combining with oxygen and again liberating that oxygen, just as it does in the living tissues.

On the other hand, the peculiar property which has been inferred for chlorophyll, namely, that of seizing the group CO from CO, and liberating O under the influence of sunlight, ceases altogether (as far as we know) when the chlorophyll is detached from the living protoplasm of an organism, and no effect of any kind upon CO, can be produced by its agency when thus isolated.

In reference to this objection to the assumed function of chlorophyll, it may be urged that the chlorophyll, when extracted from the chlorophyll-grain, is chemically altered by the solvent (alcohol or ether) used. To this it appears there is a complete answer. By chlorophyll we mean clearly enough the green substance present in the chlorophyll corpuscles. This substance is green in virtue of a specific absorption of light, which happens to be of such

a nature as to cause definite well-marked bands of

absorption in the spectrum of light which has passed through it. The solution obtained by appropriate treatment of green leaves gives precisely the same absorptionbands as does the green substance in the plant (the whole series being moved a very little to the blue end according to the known law that absorption-bands travel in that direction when a less dense solvent is substituted for a more dense one). Hence the green substance, to which we have to limit the term chlorophyll, may be inferred to exist unchanged in the solution.

The persistence of a complex banded absorption spectrum is, according to a large range of observations on the phenomena of absorption, a distinct proof of the persistence of chemical and molecular constitution. Those who of a part of the evidence against the specific activity of are not prepared to admit this must, whilst thus disposing

chlorophyll, abandon the only evidence we have in favour of the specific activity of hæmoglobin, for it is upon the identity of the absorption-spectra of hæmoglobin, both in the organism and in the crystalline form, that we have to depend for the inference that the substance which we

extract is the same substance as that which circulates in

the blood and colours the muscles.

directly proved with regard to the supposed CO-decomposIt cannot, however, be stated that a negative has been ing property of chlorophyll. It is possible that chlorophyll, when extracted by solvents from the chlorophyll-corpuscles, may yet be shown to possess that property. The solvents themselves may, so long as they are present, exert an inhibitory effect. Whilst ether and alcohol may do so it

1 As an example see Letourneau, "Biology:" Library of Contemporary Science, 1878, p. 97.

BB

is possible that vegetable fats may be more propitious, or that some other solvents may be found more closely resembling the natural solvent of the chlorophyll-corpuscle than those at present known.

Apart, however, from the absence of sufficient evidence to warrant the assumption that chlorophyll has a specific chemical action on carbonic acid in the presence of sunlight, there have to be considered (1) facts connected with the part played by the sunlight which render it improbable that chlorophyll is thus concerned, and (2) facts which point to another use for chlorophyll, and one which involves that concomitance of chlorophyll with CO, decomposition which has been most strongly urged in favour of its supposed special property; (3) facts which suggest that such chemical activity as that sometimes attributed to chlorophyll is the special property of protoplasm, or rather of the higher members of that ever-ascending and descending series of albuminoid. bodies occurring in organisms, of which series the theoretical apex is entitled to the name "protoplasm" (so far as the term can receive a chemical limitation).

1. If chlorophyll were the active agent in CO, decomposition under the influence of sunlight, we should expect the rays absorbed by chlorophyll to be those most efficient in promoting such decomposition. Such, it has been shown by Sachs and others, is not the case. Light which has traversed a solution of chlorophyll is still efficient in exciting the plant-cell (whatever part of the cell may be called into play) to the decomposition of CO, and liberation of O. It is true that the activity of light thus treated is diminished, but that is explained by the fact that the rays of the whole visible spectrum are some more, some less, capable of exciting the decomposition, and that the total amount of light transmitted is much diminished. The maximum evolution of oxygen by green plants is not in the red rays where chlorophyll most absorbs, nor in the indigo and violet which it also largely absorbs, but in the yellow, the orange, and the green, which it allows to pass entirely except for three very narrow and feeble absorption bands.

2. The action of light on the chemical motion of protopla m (and we know of no changes in protoplasm which can be considered as other than chemical) is known to be a very important one. Supposing that chlorophyll is not directly related to the action of light in exciting the decomposition of carbonic acid by the true living substance of green plants, there are yet other activities of the protoplasm of the plant-cell to which it may be related. Engelmann has recently shown that luminous rays (independently of the obscure heat-rays) cause sudden contraction of protoplasmic organisms devoid of chlorophyll or other pigment, whilst the expansion of Æthalium on the surface of tan in the dark, and its contraction beneath the tan during sunlight, is a well-known phenomenon capable of experimental demonstration. The action of solar rays other than those highly endowed with the property of exciting thermal vibrations upon the living tissues of both animals and plants appears to be more general than has been usually admitted,1 and due

The cases of "sun-burn" produced by the glare of the electric light without any accompanying sensation of heat, related both by Prof. Tyndal and Mr. Norman Lockyer, are in point. Further also the remarkable influence fexposure to sunlight on the phosphorescence of Beroë, as recorded by Prof. Allman, Proc. Roy. Soc. Edinburgh, 1862.

to a direct influence upon the protoplasm of living cells. This being the case, it is not surprising that, supposing the active agent in the decomposition of carbonic acid in green plants to be the protoplasm itself, that activity should be excited by the same part of the spectrum which excites the human retina. At the same time it would not be surprising that other specific chemical activities should be promoted in protoplasm by the incidence of luminous rays, and it may well be that chlorophyll has a relation to these activities rather than to the decomposition of carbonic acid.

It is here that the important suggestion of Prof. Pringsheim (see NATURE, vol. xx. p. 86), based on very simple but careful observations, comes in. The respiration of the plant-cell is promoted according to these observations by the action of light. Intense sunlight in the presence of oxygen gas causes the chlorophyll of a plant-cell (as watched with the microscope), to oxidise and disappear. Similarly it causes decomposition and disruption of the protoplasmic portion of the cell. Ultra-red rays have not this effect, and extreme red rays have it but feebly, whilst the more refrangible rays, even to an extreme distance in the blue, exhibit it powerfully. Here then is a chemical action taking place in the plant-cell under the influence of light, and in this case the rays which are active appear to be more nearly coincident with those absorbed by chlorophyll than in the case of CO2 decomposition. It does not appear that the oxidising process is non-existent in the absence of light, but merely that it is far more active in the presence of light. Accordingly Prof. Pringsheim suggests that the true function of chlorophyll is, by its general absorbent action on light, to protect the protoplasm of the cell from this excessive oxidation, and especially to protect the Oxidation protoplasm of the chlorophyll corpuscles. being thus entirely or nearly entirely arrested in the chlorophyll corpuscles, whilst proceeding in a lessened. degree in the general protoplasm of the cell, the protoplasm of the chlorophyll corpuscles is at liberty under the influence of those rays of light which are allowed to pass by the chlorophyll (the very reverse of former suppositions on the subject) to decompose carbonic acid and synthesise the elements of starch (or of hypochlorin). And we know, as stated above, that the rays of light allowed to pass by chlorophyll are those which are the most efficient in the excitation of this activity.

Prof. Pringsheim's hypothesis thus reconciles in a most ingenious manner the concomitance of chlorophyll and CO2-decomposition with the inactivity of that body as isolated and the apparent irrationality of its absorptionphenomena.

3. That so special an activity as the decomposition of carbonic acid and synthesis of the elements of starch is due to protoplasm itself and not to a body which, like chlorophyll, appears to be of a comparatively simple chemical nature, is probable on à priori grounds.

Throughout the organic world-so far as our knowledge goes, and it may be admitted that it does not go very farthe more complex chemical processes connected with nutrition on the one hand, and secretion on the other appear to be carried on directly under the influence of the living substance of cells. We know of no formed-products similar to chlorophyll which stand between the gland

protoplasm of animals and the material which they break down into secretions, such as the components of bile, or such as the hydrochloric and sulphuric acid of other glands. But still more important are the examples of elaboration and synthesis presented by some of the lowest organisms. Without chlorophyll, or, as far as we have any ground for conclusion, any such intermediary, the protoplasm of the Bacteria acts upon ammonium acetate so as to build up carbon, nitrogen, hydrogen, and oxygen into an albuminoid compound like itself. Such action appears to be the specialty of protoplasm, for even when a share of the work is attributed in the green plant to the green pigment chlorophyll, yet we have to come back to protoplasm to finish the job and do the really difficult feat of combining carbo-hydrates and ammonia. By dismissing chlorophyll from the operation altogether we do not add materially to the capricious many-sidedness of protoplasm. Here it can take carbon from carbonic acid and nitrogen from ammonia, there it can do with nothing less than an acetate, there again it must have a tartrate at least, and in a fourth example it perishes without albumens.

If the green pigment has been misrepresented in the foregoing indictment, and if it really is something more than a screen for protoplasm, its character must be reestablished by direct demonstration of its capabilities. The facts, as at present in evidence, look very much indeed as though chlorophyll had been assigned a position of unmerited dignity.1 E. RAY LANKESTER

HANDBOOK OF BOTANY

Handbuch der Botanik. Bearbeitet und herausgegeben

von Dr. N. J. C. Müller, Professor in Münden. Erster Band, Erster Theil. Anatomie und Physiologie der Gewächse. (Heidelberg, 1880: Carl Winter's Uni

versitätsbuchhandlung.)

THE

HE volume before us is the first of a work which is to treat of all the departments of the science of botany. In his preface Prof. Müller explains that he has been led to undertake this very serious task by the con. viction that unity of design is the first essential in an educational work such as this is to be, and that this unity cannot be attained unless all the parts of it come from the same hand. Possibly his estimate of the value of this unity may be correct, but it must not be forgotten that the division of a labour such as this secures one very important advantage, namely, the complete treatment of each of the separate parts, and this may after all be quite as important as the unity of design.

These considerations naturally recall to memory the handbook which was planned on so magnificent a scale by Hofmeister. That work is still unfinished, and long periods of time intervened between the publication of volumes of it by the different authors, so that, as it is, the work necessarily exhibits but little unity of design, and must therefore, from Prof. Müller's point of view, possess comparatively little educational merit. As a

1 Mr. Vines suggests that if Pringsheim's view be correct, then it might be possible by aid of an artificial chlorophyll screen to excite the protoplasm of fungi or even of animals to the decomposition of carbonic acid. This seems to me unlikely on account of the definitely characteristic chemical activities acquired by protoplasm in different organisms. But it certainly would be worth while trying the experiment with an etiolated green plant and an artificial chlorophyll screen. The experiment would be decisive.

matter of fact, however, the deficient unity is hardly noticed, for the parts are so complete in themselves that they can stand alone, and are of permanent value as books of reference.

We will now proceed to form an estimate of the success which has attended Prof. Müller in the execution of the first part of his plan. In this volume he treats more especially of the physiology of plants, giving also some account of their coarser anatomy, and he does so with so much detail that he fills more than six hundred pages. It will perhaps be well to defer any remarks upon the latter subject until it has been treated, as Prof. Müller promises, in a more complete manner in subsequent volumes.

With regard to physiology, then, it must be admitted that Prof. Müller's work is an elaborate one, and that it gives evidence of much labour and thought; but yet the result cannot be regarded as other than unsatisfactory. It contains a great deal of information, some of it of a very recondite description, but it is not arranged in a clear and logical manner so that the student can readily grasp the facts and appreciate their mutual relations. There is a want of proportion or perspective about it, and the result is that the fundamental facts do not stand out clearly from those of secondary importance. The mode of stating the facts is not always all that could be desired. On p. 1, for instance, protoplasın is spoken of as being fluid (flüssig), a mode of describing its consistence which is generally considered to be inaccurate. But the most serious defect in the book is the want of definite statements of the conditions under which the more im

portant vital phenomena take place. There is a sort of vagueness about Prof. Müller's account of these which. will prove distressing to any student who reads his book. For example, let us take the discussion of the mode of growth in surface of the cell-wall. On p. 100 there is a very brief statement of the theory of growth by intussusception; on p. 146 there is an account of Nægeli's theory of the structure of the cell-wall; but when we turn to p. 170, where the account of the actual growth of the cell-wall is given, no reference is made to either of the first importance in explaining the process of growth. these theories, which are generally regarded as being of Then as to the turgid condition of the growing cell: this is certainly mentioned on p. 170 and on p. 193, but no hint is given of the means by which this condition is produced and maintained, or of its significance in the have considerable difficulty in obtaining anything like a process of growth. It is evident that a student would from Prof. Müller's account of it. clear idea of the mode of growth in surface of a cell wall

Müller's account of the circulation of liquids in the plant, Again, there is no clear distinction made, in Prof. between the slow movement of solutions of nutritious substances and the rapid movement of water in connection with the process of transpiration; and the paths along which the liquids travel in these two movements are by no means clearly traced. The recent important researches of Sachs and of von Höhnel on this subject appear to have been overlooked.

Further, in discussing the decomposition of carbonic acid by chlorophyll under the influence of sunlight, Prof. Müller makes no clear statement as to which of the