PREFACE 



The present volume fulfils in a general way the inten- 

 tion, expressed in the preface to the first edition ^ of the 

 work Social and Ethical Interpretations, of taking up some 

 of the biological problems most closely connected with 

 psychological ones and falHng under the general scope of 

 the genetic method. General biology is to-day mainly 

 theory of evolution, and its handmaid is theory of indi- 

 vidual development. 



The composition of the work — like that of the com- 

 panion volumes — has been gradual, and the positions 

 taken have been in many cases already presented in jour- 

 nals under various dates since 1895. This is especially 

 true of the matter contained in Part II., regarding which 

 a word of more detailed explanation is necessary. 



Since the first publication of the position, called in these 

 pages and earlier 'Organic Selection,' by three writers 

 independently, — Prof essor H. F. Osborn, Principal Lloyd 

 Morgan, and myself, — considerable discussion has arisen 

 about the theory, its meaning and value, and the original 

 papers announcing the point of view have been under 

 somewhat close inspection. The demand for reprints of 

 these papers, in my own case — to speak only of my own 

 case — has made it seem advisable to have them put in 

 some available form much as they originally appeared. 

 Despite the difficulties in the way of doing this, arising 



1 Reprinted in the third edition (1902). 



