Weismannism tip to date (1893). 161 



genetic organisms, bud-variation 1 , &c, amply de- 

 monstrate that congenital variations due to the 

 instability of germ-plasm alone, or apart from amphi- 

 mixis, are sometimes enormous. Hence, we cannot 

 accept the gratuitous suggestion that in all other 

 cases they are too insignificant to count for anything 

 till they have been augmented by amphimixis, even 

 although we may be prepared to agree that amphi- 

 mixis is probably one important factor in the pro- 

 duction of congenital variations. What degree of 

 importance it presents in this connexion, however, 

 we have not at present any means of determining ; 

 all we can conclude with certainty is, that in some 

 cases it is demonstrably very much less than Weis- 

 mann supposes, while it is extremely improbable that 

 it is ever in any case the sole and necessary antecedent 

 to the operation of natural selection. 



This extreme improbability is shown, not only by 

 what I have already said in the previous chapter, and 

 need not here repeat ; but likewise by the " several 

 considerations " which Darwin has adduced with 

 regard to this very point, and which, as he says, 

 " alone render it probable that variability of every 

 kind is directly or indirectly caused by changed 

 conditions of life," with the consequence that " those 

 authors who attribute all variability to the mere act 

 of sexual union are in error." I have already quoted 

 these words further back in the present chapter, in 

 order to show that by now attributing the origin 



1 Professor Weismann has now considered more fully than heretofore 

 the phenomena of bud-variation {The Germ-plasm, pp. 439-442); but 

 as he continues (though with diffidence) to take substantially the same 

 view of them as that which I have already quoted on pp. 95-96, it is 

 needless for me to re-discuss the matter here. 



M 



