^PREFACE. 



The general tendency of recen: scientific literature 

 dealing with the problem of organic evolution may fairly 

 be characterized as distinctly and prevailingly unfavorable 

 to the Darwinian theory of Natural Selection. In the 

 series of chapters herewith offered for the first time 

 to English readers. Dr. Dennert has brought to- 

 gether testimonies which leave no room for doubt 

 about the decadence of the Darwinian theory in the 

 highest scientific circles in Germany. And outside 

 of Germany the same sentiment is shared generally by 

 the leaders of scientific thought. That the popularizers of 

 evolutionary conceptions have any anti-Darwinian tenden- 

 cies cannot, of course, be for a mom.ent maintained. For 

 who would undertake to popularize what is not novel or 

 striking? But a study of the best scientific literature re- 

 veals the fact that the attitude assumed by one of our fore- 

 most American zoologists. Professor Thomas Hunt Mor- 

 gan, in his recent work on "Evolution and Adaptation," is 

 far more general among the leading men of science than is 

 popularly supposed. Professor Morgan's position may be 

 stated thus: He adheres to the general theory of Descent, 

 i.e., he beUeves the simplest explanation which has yet 



