156 Darwin, and after Darwin. 



has been absolutely continuous " since the first origin 

 of sexual propagation," always occupying a separate 

 "sphere" of its own, at all events to the extent of 

 never having been modified by the body substance 

 in which it resides (Lamarckian factors); or, are 

 we to hold that this '• germ-plasm," " stirp," or " forma- 

 tive-material," has been but relatively continuous, 

 so as to admit of some amount of commerce 

 with body-substance, and therefore to admit of 

 acquired characters, when sufficiently long continued 

 as such, eventually becoming congenital.? If this 

 question be answered in the latter sense, of course 

 the further question arises as to the degree of 

 such commerce, or the time during which acquired 

 characters must continue to be acquired in suc- 

 cessive generations before they can sufficiently 

 impress themselves on the substance of heredity 

 to become congenital. But this is a subordinate 

 question, and one which, in the present state of 

 our information, it seems to me almost useless to 

 speculate upon. My own opinion has always been 

 the same as that of Mr. Galton ; and my belief is 

 that eventually both Weismann and his followers 

 will gravitate into it. It was in order to precipitate 

 this result as far as possible that I wrote the 

 Exavii)iation. If it ever should be accomplished, 

 Professor Weismann's elaborate theory of evolution 

 will have had its bases removed. 



