﻿130 Darwin, and after Darwin. 



time of germination the changed conditions should 

 effect a re-shuffling (or any other modification) of 

 the " germ-plasm " in the seeds — and this in such 

 a manner that the effect on the residual germ-plasm 

 reserved for future generations is precisely similar to 

 that produced on the somatic tissues of the developing 

 embryo. 



In the second place, as we have seen, in some of 

 the foregoing cases the changes were produced 

 months — and even years — before the seeds of the first 

 germination were formed. Therefore the hereditary 

 effect, if subsequent to the period of embryonic ger- 

 mination, must have been produced on germ-plasm 

 as this occurs diffused through the somatic tissues. 

 But, if so, we shall have to suppose that such germ- 

 plasm is afterwards gathered in the seeds when these 

 are subsequently formed. This supposition, however, 

 would be radically opposed to Weismann's theory of 

 heredity : nor do I know of any other theory with 

 which it would be reconcilable, save such as entertain 

 the possibility of the Lamarckian factors. 



Lastly, in the third place, I deem the following 

 considerations of the highest importance : — 



"As other instances in which peculiar structures are now 

 hereditary may be mentioned aquatic plants and those producing 

 subterraneous stems. Whether they be dicotyledons or mono- 

 cotyledons, there is a fundamental agreement in the anatomy 

 of the roots and stem of aquatic plants, and, in many cases, of 

 the leaves as well. Such has hitherto been attributed to the 

 aquatic habit. The inference or deduction was, of course, based 

 upon innumerable coincidences ; the water being supposed to 

 be the direct cause of the degenerate structures, which are 

 hereditary and characteristic of such plants in the wild state. 

 M. Costantin has, however, verified this deduction, by making 



