vi EVOLUTION AND GENETICS 



A discussion of these two problems in their histor- 

 ical setting is one of the princij^al themes treated in 

 the following pages. 



The four original lectures (chapters) have been 

 subdivided and enlarged into thirteen chapters. Two 

 of these are entirely new, one dealing with the non- 

 inheritance of acquired characters ( copied with slight 

 changes from the Yale Review for July 1924), the 

 other a criticism of the evidence of human inherit- 

 ance. The somewhat acrimonious discussion taking 

 place at the present time concerning racial differ- 

 ences in man, a discussion in which "nature" and 

 "nurture" are often confused, mav furnish an excuse 

 for the addition of this final chapter. 



T. H. ]\I0RGAN 



3Iarch 1925 



