602 



SCIENCE. 



[N. S. Vol. I. No. -22. 



meres of tlie molecules of living matter 

 were the source of its varying potentialities 

 as manifested in its protean changes of 

 specific form and function. That some me- 

 chanical and consequently dynamical in- 

 terpretation of these transformations may 

 yet be forthcoming is, I take it, distinctly 

 foreshadowed by the advances in the newer 

 theories of stereo-chemistry developed by 

 LeBel and Van't Hoff. If this is the case 

 we may yet hope for a mechanical and 

 dynamical explanation of the phenomena 

 of life and inheritance. Especially is this 

 true if we further suppose that the large 

 molecules of living plasma, are rather feebly 

 held together by a force almost of the na- 

 ture of cohesion. We may be permitted 

 thus to find an explanation of that phenom- 

 enon which is alwaj^s so characteristic of 

 living matter, namely, the large and rela- 

 tively fixed amount of water it contains, 

 and also the mobility of its molecules in 

 respect to one another, its jelly-like char- 

 acter at one instant, its fluidity and power 

 of motion at another. It is indeed probable 

 that the amount of water contained in liv- 

 ing matter is controlled within certain limits 

 by the forces of cohesion exerted between 

 adjacent molecules against the osmotic 

 pressure or capillary action of water tend- 

 ing to drive them asunder, as supposed by 

 Nageli, in his hypothesis of micellae. Such 

 an hypothesis enables us to explain much 

 that is otherwise quite xmintelligible in re- 

 lation to living things. It renders us an 

 explanation of amceboid motion, of the 

 surface tensions of protoplasm and lastly 

 of metabolism itself through osmosis and 

 the specific characters of the chemical 

 transformations that must take place in 

 each kind of living substance. 



Such an hj-pothesis may also afibrd us 

 mechanical constructions of atoms, grouped 

 into very large metameric or polymeric 

 molecules of the utmost diversity of powers, 

 capable of undergoing a long series of suc- 



cessive transformations, so as to manifc'st 

 in the long run, starting with a molecular 

 germinal aggregate, what we call ontogeny 

 or development. These transformations, 

 we must suppose, are effected bj' the metab- 

 olism incident to growth, and moreover, 

 that starting with an initial configuration 

 of a system of molecules, as a mechanical 

 and consequently a dynamical system of 

 determinate powers, in the form of a germ, 

 it cannot undergo any other transformations 

 except such as lead to an approximate re- 

 capitulation of the ancestral development 

 or phylogeny. This supposition follows 

 from the rule that must hold of determinate 

 systems of molecules, as well as of systems 

 formed of larger masses, namely, that the 

 initial changes in the configuration of such 

 a complex system must dynamical^ deter- 

 mine within certain variable limits, under 

 changing conditions, the nature of all of its 

 subsequent transformations, including those 

 due to growth and consequently increased 

 complexity. We thus escape the necessity 

 of invoking certain ' proclivities ' of physio- 

 logical units, or the necessity of appealing 

 to the growth and fission of ' biophors ' or 

 the scattering of ' determinants ' at the 

 proper times and places in the course of 

 development. We thus escape, too, the 

 mistake of assuming that a part of a germ 

 controls the whole, a proposition that has 

 been so long advocated by one school of 

 biologists that it is astounding that its fal- 

 lacy has not long since been more generally 

 understood. Such a doctrine is not credi- 

 ble in the face of the fact that we know of 

 no development except that which takes 

 place in intimate association with cyto- 

 plasm, which seems to be the principal 

 theater of metabolism and growth. We 

 cannot conceive of the transformations of 

 a germ without considering the metabolism 

 of all its parts, such as nucleus, cytoplasm, 

 centrosomes, archoplasm, chromatin, spin- 

 dles, astral figures, microsomata, etc. 



