1 62 An Examination of Weismannism. 



of all congenital variations to the direct action of 

 external conditions. Weismann has brought himself 

 into line with Darwin so far as this fundamental 

 point of doctrine is concerned. But I here re-quote 

 the words in order to show that by further attributing 

 the development of congenital variations " to the mere 

 act of sexual union." Weismann is again falling out 

 of line with Darwin. So to speak, he first performs 

 a right-about-face movement as regards his original 

 position towards the " stability of germ-plasm," and 

 immediately afterwards makes a half-turn back again. 

 Now. it is this half-turn to which I object as un- 

 warranted in logic and opposed to fact. 



In a previous chapter (pp. 66—7) I presented to him 

 the dilemma, that germ-plasm must be either ab- 

 solutely stable or else but highly stable, and that in 

 the former case his theory of amphimixis as the sole 

 cause of congenital variations would be valid, while 

 in the latter case the theory would collapse. But it 

 did not then occur to me that Weismann might seek 

 a narrow seat between the horns of this dilemma, by 

 representing that germ-plasm is universally unstable 

 up to a certain very low degree of instability — viz., 

 exactly that degree which is required for starting 

 a congenital variation by means of external causes, 

 without its being possible for the variation to become 

 perceptible unless afterwards increased by means of 

 amphimixis. And now that this extremely sophis- 

 tical position has been adopted, I cannot see any 

 imaginable reason for adopting it other than a last 

 endeavour to save as much as possible of his former 

 theory of evolution. There can be nothing in the 

 nature of thinsrs thus to limit, within the narrowest 



