192 UNIVERSITY OF MISSOURI BULLETIN 



EXPERIMENTAL EVOLUTION 



Leaving the problems of individual development, let us 

 now turn to the questions of racial development of which the 

 questions of individual development are a part. Here, also, 

 we find experimental studies assuming an increasing impor- 

 tance, for in no other line of zoological investigation has the 

 advent of the experimental method wrought more profound 

 changes than in the problems connected with the doctrine of 

 evolution. 



When we consider the extent to which the conclusions 

 of Darwin were based upon his own first-hand observations 

 and experiments, it is astonishing that his followers should 

 have so soon reached a place where discussion was far re- 

 moved from an intimate acquaintance with the actual phe- 

 nomena. Only the acceptance and eager pushing forward of 

 the experimental method saved us the reproach of being 

 almost as dead to nature as the minds of men are reputed 

 to have been during the middle ages. 



The return to nature after this barren period of post- 

 Darwinian discussion occurred, as is usually the case in such 

 movements, through the gradual emergence of a number of 

 lines of investigation which had progressed steadily for some 

 years without attracting much attention, the best example 

 of this being the work of Mendel and others upon heredity. 

 This began with the hydridization experiments which led 

 Mendel, in 1866, to the discovery of his law or laws of 

 heredity, but which failed to attract the attention of anyone 

 who could appreciate their importance until many years after 

 his death, when they were independently rediscovered by a 

 number of other workers about the year 1900. 



Let us review briefly the more obvious aspects of 

 Mendelism and related work upon variation and heredity. 

 The minute variations upon which so much emphasis was 

 placed in Darwin's theory of natural selection appear to be 

 but one side of the field of variation and the one of least 



