September 5, 1912] 



NATURE 



became misty and has now disappeared. Similarly 

 the chemistry of living- organisms, which is now a 

 recognised branch of organic chemistry, but used to 

 be considered as so much outside the domain of the 

 chemist that it could only be dealt with by those whose 

 special business it was to study "vital" processes, is 

 passing every day more out of the hands of the 

 tiiologist and into those of the pure chemist. 



The Colloid Constilution of Living Matter. — Identity 

 of Physical and Chemical Processes in Living and 

 Non-living Matter. 

 Somewhat more than half a century ago Thomas 

 ■Graham published his epoch-making observations 

 relating to the properties of matter in the colloidal 

 state : observations which are proving all-important in 

 assisting our comprehension of the properties of living 

 substance. For it is becoming every day more 

 .apparent that the chemistry and physics of the living 

 organism are essentially the chemistry and physics of 

 nitrogenous colloids. Living substance or protoplasm 

 .always, in fact, takes the form of a colloidal solution. 

 In this solution the colloids are associated with 

 crystalloids (electrolytes), which are either free in the 

 solution or attached to the molecules of the colloids. 

 Surrounding and enclosing the living substance thus 

 constituted of both colloid and crystalloid material is 

 a film, probably also formed of colloid, but which 

 may have a lipoid substratum associated with it 

 .(Overton). This film serves the purpose of an osmotic 

 membrane, permitting of exchanges by diffusion be- 

 tween the colloidal solution constituting the proto- 

 plasm and the circumambient medium in which it 

 Jives. Other similar films or membranes occur in the 

 interior of protoplasm. These films have in many 

 cases specific characters, both physical and chemical, 

 thus favouring the diffusion of special kinds of 

 material into and out of the protoplasm and from 

 one part of the protoplasm to another. It is the 

 changes produced under these physical conditions, 

 associated with those caused by active chemical agents 

 formed within protoplasm and known as enzymes, 

 that effect assimilation and disassimilation. Quite 

 similar changes can be produced outside the body (in 

 ■vitro) by the employment of methods of a purely 

 physical and chemical nature. It is true that we are 

 not yet familiar with all the intermediate stages of 

 transformation of the materials which are taken in by 

 a living body into the materials which are given out 

 from it. But since the initial processes and the final 

 results are the same as they would be on the assump- 

 tion that the changes are brought about in conformity 

 with the known laws of chemistry and physics, we 

 may fairly conclude that all changes in living sub- 

 stance are brought about by ordinary chemical and 

 physical forces. 



Similarity of the Processes of Growth and Reproduc- 

 tion in Living and Non-living Matter. 

 Should it be contended that growth and reproduction 

 are properties possessed only by living bodies and 

 constitute a test by which we may differentiate 

 between life and non-life, between the animate and 

 inanimate creation, it must be replied that no con- 

 tention can be more fallacious. Inorganic crystals 

 grow and multiply and reproduce their like, given a 

 ■supply of the requisite pabulum. In most cases for 

 each kind of crystal there is, as with living organisms, 

 a limit of growth which is not exceeded, and further 

 increase of the crystalline matter results not in further 

 increase in size but in multiplication of similar crystals. 

 Leduc has shown that the growth and division of 

 artificial colloids of an inorganic nature, when placed 

 in an appropriate medium, present singular re- 

 semblances to the phenomena of the growth and 



NO. 2236, VOL. go] 



division of living organisms. Even so comple.K a 

 process as the division of a cell-nucleus by karyokinesis 

 as a preliminary to the multiplication of the cell by 

 division — a phenomenon which would primd facie have 

 seemed and has been commonly regarded as a dis- 

 tinctive manifestation of the life of the cell — can be 

 imitated with solutions of a simple inorganic salt, 

 such as chloride of sodium, containing a suspension 

 of carbon particles ; which arrange and rearrange 

 themselves under the influence of the movements of 

 the electrolytes in a manner indistinguishable from 

 that adopted by the particles of chromatin in a dividing 

 nucleus. And in the process of se.vual reproduction, 

 the researches of J. Loeb and others upon the ova of 

 the sea-urchin have proved that we can no longer 

 consider such an apparently vital phenomenon as the 

 fertilisation of the egg as being the result of living 

 material brought to it by the spermatozoon, since it 

 is possible to start the process of the ovum and the 

 resulting formation of cells, and ultimately of all the 

 tissues and organs — in short, to bring about the 

 development of the whole body — if a simple chemical 

 reagent is substituted for the male element in the 

 process of fertilisation. Indeed, even a mechanical or 

 electrical stimulus may suffice to start development. 



The Question of Vitalism and Vital Force. 

 Kurz und gut, as the Germans say, vitalism as a 

 worl^cing hypothesis has not only had its foundations 

 undermmed, but most of the superstructure has toppled 

 over, and if any difficulties of explanation still persist, 

 we are justified in assuming that the cause is to be 

 found in our imperfect knowledge of the constitution 

 and working of living material. At the best vitalism 

 e.xplains nothing, and the term "vital force" is an 

 expression of ignorance which can bring us no further 

 along the path of knowledge. Nor is the problem in 

 any way advanced by substituting for the term 

 "vitalism" " neo-vitalism," and for "vital force" 

 " biotic energy."* "New presbyter is but old priest 

 writ large." 



This Possibility of the Synthesis of Living Matter. 

 Further, in its chemical composition we are no 

 longer compelled to consider living substance as pos- 

 sessing infinite complexity, as was thought to be the 

 case when chemists first began to break up the pro- 

 teins of the body into their simpler constituents. The 

 researches of Miescher, which have been continued and 

 elaborated by Kossel and his pupils, have acquainted 

 us with the fact that a body so important for the 

 nutritive and reproductive functions of the cell as the 

 nucleus — which may be said indeed to represent the 

 quintessence of cell-life — possesses a chemical constitu- 

 tion of no very great complexity ; so that we may 

 even hope some day to see the material which com- 

 poses it prepared synthetically. And when we consider 

 that the nucleus is not only itself formed of living 

 substance, but is capable of causing other living sub- 

 stance to be built up ; is, in fact, the directing agent 

 in all the principal chemical changes which take place 

 within the living cell, it must be admitted that we are 

 a long step forward in our knowledge of the chemical 

 basis of life. That it is the form of nuclear matter 

 rather than its chemical and molecular structure which 

 is the important factor in nuclear activity cannot be 

 supposed. The form of nuclei, as every microscopist 

 knows, varies infinitely, and there are numerous living 

 organisms in which the nuclear matter is without 

 form, appearing simply as granules distributed in the 

 protoplasm. Not that the form assumed and the 



8 B. Moore, in "Recent Adv.-\nces in Fhysiology," jgc6; Moore and 

 Roaf,_ i^i'tf. ; and "Further Advances in Physiology," 1909 Mocre lays 

 especial stress on the transformations of energy which occur in protoplasm. 

 .See on the question of vitalism Gley {Revue Scientifi<juc, igii) and 

 D'Arcy Thompson (Address 10 Section D at Portsmouth, 1911). 



