236 Theories Treating of Inheritance 



on, there would be a single identical influence exerted 

 upon the nuclei of all the cells without exception, which 

 makes it conceivable that thereby the special nuclei of the 

 different cells, and consequently of the germ cells also, 

 could all inherit the new reactive property, which would 

 be added to the other special characters already present in 

 each nucleus and different in the different cells. 



But in the case, for instance, of a certain muscle, 

 which develops to a greater size because of a definite 

 modification in its local, trophic, functional stimulus, is it 

 possible to make the analogous statement that there is 

 thus obtained a new state of the body which brings about 

 a modification in the idioplasmic substance of all the cells 

 of the organism without exception the same modifica- 

 tion in each of them ? Certainly this modification induced 

 in the trophic functional stimulus of a muscle and the 

 greater development thereby provoked in it will exert an 

 influence on all or nearly all parts of the organism; but 

 the most probable supposition and that best corresponding 

 with the facts would be that the reaction is different in 

 each part. This case at least is quite different from that 

 in which one has to do with the transmission of a definite 

 infection or immunity, and cannot be compared with it 

 without further consideration. 



In short Hertwig supposes that every local material 

 modification which appears at a given point of the idio- 

 plasm as a reaction to "a new functional stimulus extends 

 at once throughout the whole idioplasm, so that the latter 

 becomes modified uniformly everywhere, like a true 

 physiologic unit : 



"In the organism considered as a physiologic unit of 

 life the actions of all individual organs, tissues and cells 

 must be combined into a complex common action, the 



