TRAXSMISSIBILITY OF FUNCTIONAL MODIFICATIONS 63 



which any part may have undergone, whether due to external or 

 internal influences, or through use and disuse. 



In this manner Darwin sought to attribute to the germ-cells 

 the power of giving rise, in the course of their development, to the 

 same variations as the individual had acquired during its lifetime 

 in consequence of external conditions or functional influences. 



I abstain from analj^sing the assumptions here made; their 

 improbability and their contradictions to established facts are so great 

 that it is not necessary to emphasize them ; the theory shows plainly 

 that it is necessary to have recourse to very improbable assumptions, 

 if an attempt is to be made to find a theoretical basis for the trans- 

 mission of acquired (somatogenic) characters. Even when Darwin 

 formulated his theory of Pangenesis his assumptions were hardly 

 reconcileable with what was known of cell-multiplication ; now they 

 are above all irreconcileable with the fact that the germ-substance 

 never arises anew, but is always derived from the preceding genera- 

 tion — that is, with the continuity of the germ-plasm. 



If we were now to try to think out a theoretical justification we 

 should require to assume that the conditions of all the parts of the 

 body at every moment, or at least at every period of life, were 

 reflected in the corresponding primary constituents of the germ-plasm 

 and thus in the germ-cells. But, as these primary constituents 

 are quite different from the parts themselves, they would require to 

 vary in quite a different way from that in which the finished parts 

 had varied ; which is very like supposing that an English telegram 

 to China is there received in the Chinese languao-e. 



In spite of this almost insuperable theoretical obstacle, various 

 authors have worked out the idea that the nervous system, which 

 connects all parts of the body with the brain and thus also with each i_ 

 other, communicates these conditions to the reproductive organs, and 

 that thus variations may arise in the germ-cells corresponding to 

 those which have taken place in remote parts of the body. 



Even supposing it were proved that every germ-cell in ovar}'- 

 or testis was associated with a nerve-fibre, what could be transmitted 

 to it by the nerves, except a stronger or weaker nerve-current 1 

 There is no such thing as qualitative differences in the current ; how 

 then could the primary constituents of the germ be influenced by 

 the nerve-current, either individually or in groups, in harmony with 

 the organs and parts of the body corresponding to them, much less 

 be caused to vary in a similar manner ? Or are we to imagine that 

 a particular nerve-path leads to every one of the countless primary 

 constituents ? Or does it make matters more intelligible if we assume 



