Theories of Chemical Development 297 
special chemical change. This chemical change would 
later become transmitted to the germ plasm by means 
of the metabolism.??° 
One can not rightly comprehend here, how a special 
chemical modification, produced in the germ plasm by 
a change of form in the adult organism, can later give 
rise to such a development by that germ plasm as to 
reproduce the same change of form at the proper time 
in the new organism. If the chemical variation cor- 
responding to a definite change of form were provoked 
by the germ plasm in the new organism only at the 
time when this latter reached the same age and conse- 
quently a state of being which would be the same in its 
entirety as that of the parent organism when this given 
variation of form supervened in it, and were confined 
to the same limited zone in which this chemical variation 
was produced in that parent organism, then the concep- 
tion of an actual reversibility of the phenomena would 
not be in itself at all impossible, that is it would not be 
impossible that the same chemical phenomenon might 
provoke in the new organism the same variation of form 
by which it had itself been produced in the parent orgar~ 
ism. But in our case on the contrary this chemical varia- 
tion, no matter whether it transforms the whole chemical 
composition of the germ plasm or only a part, will com- 
mence to act upon the new organism immediately, at the 
very commencement of its development, and will modify 
therefore not merely a limited part of the cells of the 
organism, but all the cells without exception. How then 
could this same chemical change, which operates immedi- 
ately at the commencement of development and conse- 
21°Roux: Ibid. P. 61. 
