MODERN BIOLOGY 583 



cells would be reduced to a relatively simple sequence of chemical processes. 

 There can be no doubt, however, that Loeb has simplified overmuch. Other 

 investigators have, in fact, produced the same developmental phenomena 

 by entirely different methods. Among those who have worked in this field 

 may be mentioned, apart from Loeb's own pupils, Yves Delage (1854-1910), 

 professor at Paris, who worked out his own method of developing the sea- 

 urchin's egg, and A. Bataillon, professor at Dijon, who acquired a name 

 especially as a result of his experiments with the frog's egg; by simply 

 pricking the egg with a needle dipped in serum, he caused the frog's eggs 

 to develop into larvas — a method that "activates" the egg in an entirely 

 different way from Loeb's. Here we obviously have a metabolistic process 

 within the very mass of the egg, set free by mechanical irritation — as a 

 matter of fact, the dose of serum has latterly proved to be superfluous — 

 although the adipose splitting can in this case also be established; it is here 

 induced by the egg's own vital manifestations and not by any solvent in- 

 troduced from outside. Loeb's theories, to which we shall revert, are gov- 

 erned entirely by his lack of interest in morphological phenomena and by 

 his consequent passion for schematizing the complex vital process. Strictly 

 speaking, most other evolutional physiologists of the new direction, from 

 however mechanical a point of view they may otherwise have regarded 

 evolution, have nevertheless divided its mechanical phenomena into those 

 having a purely external origin and those that result from specific internal 

 causes. Among the former are counted the universally observable influences 

 of heat, electricity, chemical reagents; among the latter, the various organ- 

 isms' peculiar ways of reacting to them, as well as to purely mechanical inter- 

 ferences, with their normal existence. In the course of studying these hetero- 

 geneous phenomena of reaction many of the experimental observers of our 

 own time have produced and are still producing a great number of detailed re- 

 sults of immense interest, achieved by the employment of exquisitely delicate 

 methods. For the details of this field of inquiry — still by no means ex- 

 hausted — we must refer the reader to technical literature on the subject; a 

 number of general points of view that have arisen in the course of the work 

 carried out in connexion with these subjects will be discussed later on. We 

 shall instead pass on to another form of experimental research — a field that 

 is without doubt of the greatest interest to humanity at the present time. 



■L. Experimental Heredity-research 



Earlier ideas on heredity 

 "Inheritance" and "heredity" are terms that originally belonged to the 

 judiciary and have been borrowed from it to acquire a natural meaning. 



