160 An Examination of Weismannism. 



be substantiated, it can only be so by some totally 

 distinct line of reasoning. The first statement does not 

 even tend to suggest the second ; in fact it tends to 

 suggest the precise contrary. For. obviously, there is 

 nothing in the logic of the matter to show why, if 

 all congenital variations depend for their origin on 

 the instability of germ-plasm, such instability must 

 nevertheless be always so slight that the variations 

 due to it must afterwards depend on amphimixis for 

 their development to the point where they become 

 " perceptible." As above indicated, it is surely little 

 short of absurd thus to assume that a universally 

 unstable germ-plasm universally presents only that 

 particular degree of instability which will serve to 

 accommodate Professor Weismann's newer theory of 

 heredity, and at the same time to save thus much 

 of his previous theory of evolution. 



But now, in the second place, not only is this 

 assumption wholly gratuitous, but there are many 

 considerations which render it in the highest degree 

 improbable, while there are not wanting facts which 

 appear to demonstrate that it is false. For. unquestion- 

 ably, most of the considerations which have already 

 been advanced in the preceding chapter against the 

 assumption of an absolute stability of germ-plasm, are 

 here equally available against the assumption of an 

 imperceptibly small amount of instability 1 . Similarly, 

 all the facts there given with regard to the a-sexual 

 origin of species — and even genera — of partheno- 



1 See especially pp. S6-S9. All that is there said about the unicellular 

 organisms is not, in the present connexion, affected by Weismann's 

 change of view with regard to them. We have only to substitute 

 ''primordial" or "protoplasmic" for '"unicellular," and nearly all the 

 points of the criticism remain. 



