THE STANDPOINT OF BIOLOGISTS. 31 



comparative morphology, but of the habits and modes 

 of life of a vast number of animals and plants, has 

 shown that many of the cases which Darwin was 

 doubtful about may reasonably be explained by 

 selection, and he has marshalled a vast mass of evi- 

 dence in support of the argument that acquired 

 characters, experimentally produced, are not trans- 

 mitted. 



These essays are profoundly interesting, and will 

 supply food for thought for many years, but it must 

 be admitted that Weismann has gradually been led 

 away to speculations of the most elaborate kind, built 

 upon the most flimsy substratum of fact. There is 

 evidence of this tendency even in his early writings, 

 but in his later essays, especially his recent work on 

 "The Germ Plasm: a Theory of Heredity/' 1 the 

 speculative part quite overpowers the rest. 



As those who are interested in heredity will pro- 

 bably read his works with the greatest attention, I 

 have ventured in an appendix to make clear what in his 

 works may, in my opinion, safely be looked upon as 

 speculative rather than legitimate, or even provisional, 

 generalisation, and what, therefore, may be altogether 

 omitted from the study of a practical problem such as 

 that with which we are concerned. 



1 Translated by W. Newton Parker (1893). 



