September 12, 1895] 



NATURE 



483 



teria and their host being as yet imperfectly understood. The 

 answer to the question how nature i')roduccs complicated organic 

 molecules will be much facilitated when the physiologist, by 

 experiment and observation, shall have made possible a sound 

 classification of these synthetical products based on their mode of 

 origination in the organism. 



The enlargement of the definition of organic synthesis which I 

 have advocated has been rendered necessary by the considera- 

 tion of certain questions which have arisen in connection with 

 the present condition of chemical discovery in this field. What 

 evidence is there that any one of the i8o compounds which have 

 been prepared artificially is produced in the organism by a direct 

 process of building up? Is not the opposite view quite as prob- 

 able ? May they not, from the simplest to the most complex, be 

 products of the degradation of still more complex molecules ? I 

 venture tosuggest — not with(nit some temerity lest our colleagues 

 of Sections I and K should treat me as an intruder — that this 

 view should be given a fair trial. I am aware that the opposite 

 view, especially as regards plant assimilation, has long been held, 

 and especially since 1870, when v. Bacycr advanced his cele- 

 brated theory of the formic aldehyde origin of carbohydrates. It 

 is but natural to consider that the formation of a complex mole- 

 cule is the result of a building-up process. It must be 

 remembered, however, that in the living organism there is 

 always present a compound or mixture, or whatever we like to 

 call it, of a highly complex proteid nature, which, although at 

 present indefinite from the purely chemical point of view, is the 

 essence of the vitality. Of course I refer to what biologists have 

 called proto]>lasni. Moreover, it is perhaps neces.sary to state 

 what is really nothing more than a truism, viz. that protoplasm 

 is present in and forms a part of the organism from the verj' 

 beginning of its existence — from the germ to the adult, and on- 

 wards to the end of life. Any special chemical properties per- 

 taining to protoplasm are inseparable from the animal or plant 

 until that period arrives which Kekule has hinted at when we 

 shall be able to *' build up the formative elements of living 

 organisms " in the laboratory (Nature, vol. xviii. p. 212). But 

 here I am afraid I am allowing the imagination to take a flight 

 which I told you a few minutes ago that time would not admit of 

 The view that requires pushing forward into a more prominent 

 position than it has hitherto occupied is that all the chemical 

 transformations in the organism — at any rate all the primary 

 changes — are made possible only by the antecedent combination 

 of the substances concerned with living protoplasmic materials. 

 The carbon dioxide, water, i.\:c. , which the plant absorbs must 

 have formed a compound or compounds with the protoplasmic 

 material of the chloroplasts before starch, or sugar, or cellulose 

 can be prepared. There is, on this view, no such process as the 

 direct combination of dead molecules to build up a complex sub- 

 stance. Everything must pass through the vital mill. The 

 fl protoplasmic molecule is vastly more ciimpiex than any of the 

 I compounds which we have hitherto succeeded in synthesising. It 

 I might take up and form new and unstable compounds with car- 

 bon dioxide or formic aldehyde, or sugar, or anything else, and 

 our present methods of investigation would fail to reveal the 

 process. If this previous combination and, so to speak, vitalisa- 

 tion of dead matter actually occurs, the appearance of starch as 

 the first visible product of assimilation, as taught by Sachs, or 

 ilie formation of a 12-carbon-atom sugar as the first carbo- 

 hydrate, as shown by the recent researches of Horace Brown and 

 I.. II. Morris, is no longer matter for wonderment. The 

 rliemical ecjuations given in physiological works are too purely 

 rlicmical ; the physiologists have, I am afraid, credited the 

 I hemists with too nmch knowledge — it would appear as though 

 iheir intimate familiarity with vital proces.ses had led them to 

 undervalue the importance of their prime agent. In giving 

 i\pression to these thoughts I cannt)t but feel that I am treating 

 you to the strange spectacle of a chemist plea<ling from the 

 l^hysiologists for a little more vitality in the chemical functions 

 nf living organisms. The future development of vital chemistry 

 rests, however, with the chemist and physiologists conjointly ; 

 ihe isolation, identification, and analysis of the products of vital 

 Htivity, which has hitherto been the task of the chemist, is only 

 ' he preliminary work of physiological chemistry leading up to 

 ' hemical physiolog)'. 



Protoi'i.as.mic Theory ov \;ital Synthesis. 



The supposition that chemical synthesis in the organism is 

 the result of the combination of highly complex molecules with 

 simpler molecules, and that the unstable compounds thus formed 



NO. 1350, VOL. 52] 



I 



then undergo decomposition with the formation of new products, 

 may be provisionally called the protoplasmic theor>' of vital 

 synthesis. Erom this standpoint many of the prevailing 

 doctrines will have to be inverted, and the formation of the more 

 complex molecules will be considered to precede the synthesis of 

 the less complex. It may be urged that this view simply throws 

 1>ack the process of vital synthesis one stage and leaves the 

 question of the origin of the most complex molecules still unex- 

 plained. I grant this at once ; but in doing so I am simply 

 acknowledging that we have not yet solved the enigma of life. 

 We are in precisely the same position as is the biologist with 

 respect to abiogenesis, or the so-called " spontaneous genera- 

 tion." To avoid possible misconception let me here state that 

 the protoplasmic theory in no way necessitates the assumption 

 of a special " \Ttal force." All that is claimed is a peculiar, and 

 at present to us mysterious, power of forming high-grade chemical 

 combinations with appropriate molecules. It is not altogether 

 absurd to suppose that this power is a special property of nitrogen 

 in certain forms of combination. The theorj^ is but an extension 

 of the views of Kiihne, Hoppe-Seyler, and others respecting 

 the mode of action of enzymes. Neither is the view of the 

 degradational origin of synthetical products in any svay new.' I 

 merely have thought it desirable to push it to its extreme limit 

 in order that chemists may realise that there is a special 

 chemistry of protoplasmic action, while the physiologists may 

 exercise more caution in representing vital chemical transform- 

 ations by equations which are in many cases purely hypothetical, 

 or based on laboratorj- experiments which do not run parallel 

 with the natural process. The chemical transformations which 

 go on in the living organism are thus referred back to a pecu- 

 liarity of protoplasmic matter, the explanation of which is 

 bound up with the inner mechanism of the process of assimila- 

 tion. If, as the protoplasmic theorj' implies, there must be 

 combination of living protoplasm with appropriate compounds 

 before synthesis is possible, then the problem resolves itself into 

 a determination of the conditions which render such combination 

 possible — i.e. the conditions of assimilation. It may be that 

 here also light will come from the stereochemical hypothesis. 

 The first step was taken when Pasteur found that organised fer- 

 ments had the power of discriminating between physical 

 isomerides ; a similar selective power has been shown to reside 

 in enzymes by the researches of Emil Fischer and his coadjutors. 

 Fischer has (juite recently expressed the view that the synthesis 

 of sugars in the plant is preceded by the formation of a com- 

 pound of carbon dioxide, or of formic aldehyde, with the proto- 

 plasmic material of the chloroplast, and similar views have been 

 enunciated by Stohmann. The question has further been raised 

 by van 't Hoff, as well as by Fischer, whether a stereochemical 

 relationship between the living and dead compounds entering 

 into combination is not an absolutely essential condition of all 

 assimilation. The settlement of this question cannot but lead us 

 onwards one stage towards the solution of the mystery that 

 still surrounds the chemistry of the living organism. 



Recent Discoveries of Gaseous Elements. 



The past year has been such an eventful one in the way of 

 startling discoveries that I must ask indulgence for trespassing a 

 little further upon the time of the Section. It was only last 

 year at the Oxford meeting of the British .Association that Lord 

 Rayleigh and Prof. Ramsay announced the discovery of a gaseous 

 constituent of the atmosphere which had up to that time escaped 

 detection. The complete justification of that announcement is 

 now before the world in the paper recently published in the 

 Philosophical Transactions of the Royal Society. The history 

 of this brilliant piece of work is too recent to require much re- 

 capitulation. I need only remind you how, as the result of many 

 years' patient determinations of the density of the gases oxygen 

 and nitrogen. Lord Rayleigh established the fact that atmo- 

 spheric nitrogen was heavier than nitrogen Irom chemical sources, 

 and was then led to suspect the existence of a heavier gas in the 

 atmosphere. He set to work to isolate this substance, and suc- 

 ceeded in doing so by the method of Cavendish. In the mean- 

 time Prof. R.amsay, quite independently, isolated the gas by re- 

 moving the nitrogen by means of red-hot magnesium, and the 



J See, e.g.^ Vines' '* Lectures on the Physiology of Plants," pp. 145, 

 218, 227, 233. and 234. Practically all the Rrcat classes of synthetical pro- 

 ducts are regarded as the results of the destructive metatralism of proloplxsm. 

 A special plea for protoplasmic action has also been urged, from the biological 

 side, by W. T. Thiselton-Dyer, Journ. Clicm. Soc, 1893 ; Trans. ' pp. 

 680-681 



