THE DOCTRINE OF DESCENT. i r 



theory of descent to be found ? Neither Virchow, 

 nor any one of the clerical opponents and the dualistic 

 philosophers who are perpetually reiterating this cry 

 for more certain evidence, anywhere indicate where 

 possibly such evidence is to be sought. Where in 

 all the world can we discover " facts " which will 

 speak more plainly or significantly for the truth 

 of transmutation than the facts of comparative 

 morphology and physiology; than the facts of the 

 rudimentary organs and of embryonic development ; 

 than the facts revealed by fossils and the geographical 

 distribution of organisms in short, than the collective 

 recognised facts of the most diverse provinces of 

 biological science ? 



But I am in error the certain proof that Yirchow 

 demands in order to be perfectly satisfied with the 

 evidence, is to be supplied by " experiment, the test 

 as well as the highest means of evidence." This 

 demand, that the doctrine of descent should be 

 grounded on experiment, is so perverse and shows 

 such ignorance of the very essence of our theory, 

 that though we have never been surprised at hear- 

 ing it continually repeated by ignorant laymen, from 

 the lips of a Virchow it has positively astounded us. 

 "What can in this case be proved by experiment, and 

 what can experiment prove ? 



"The variability of species, the transformation of 



