1 66 An Examination of Weismannism. 



variation. So to speak, it is his desire to reserve as 

 much as is speculatively possible from the general 

 ruin of his theory of descent, that causes him to go so 

 far to attempt so little. For I cannot suppose that he 

 himself will expect any of his readers to entertain 

 so arbitrary, fanciful, and demonstrably false an 

 assumption as the one in question. Surely it would 

 have been better to have surrendered in toto this 

 " Weismannian theory of variation/' rather than to 

 have attempted its rescue by means so plainly 

 nugatory. It might still have been held that amphi- 

 mixis plays a large and important part as one of the 

 causes of variation, and therefore also as one of the 

 factors of organic evolution. After having reversed 

 his postulate of amphimixis being the sole cause of 

 variability, and therefore having agreed with Darwin 

 that " those writers are in error who attribute all 

 variability to the mere act of sexual union," he might 

 well have questioned Darwin's further statement as to 

 its being " probable that variability of every kind is 

 directly or indirectly caused by changed conditions 

 of life." But by now assuming that variations due to 

 any causes other than amphimixis must be Ci imper- 

 ceptible " until they have been augmented by amphi- 

 mixis, Weismann is shutting out, with a futile hypo- 

 thesis, the important question as to whether, or how 

 far, amphimixis really is a cause of variation. Observe, 

 the case is not as it might have been were there no 

 reasons assignable for the occurrence of sexual pro- 

 pagation, other than that of assisting in the production 

 of congenital variations. The theory of " rejuve- 

 nescence," for example, is prima facie a. more probable 

 one than that which ascribes to sexual propagation 



