APPENDIX 193 



advantageous trend to appear. Such an effect is not only conceivable ; it seems 

 not unlikely that in some instances it may have been important. 



I have said above that I cannot quite agree with Morgan, Osborn, and 

 Baldwin in the emphasis they have laid upon the accommodation of the in- 

 dividual as a guide to the course of evolution by natural selection. Before 

 commenting further on this suggestion, let me quote in part Professor Conn's * 

 statement of the principle of "organic selection," as this factor in evolution 

 has been called : 



" The essence of the theory of organic selection is, that these acquired 

 variations will keep the individuals in harmony with their environment, and 

 preserve them under new conditions, until some congenital variation happens to 

 appear of a proper adaptive character. The significance of this conception is 

 perhaps not evident at a glance. It may be made clear by considering, for 

 illustration, the problem of the development of habits and organs adapted to 

 each other. . . , 



" Perhaps a concrete case may make this somewhat obscure theory a little 

 clearer. Imagine, for example, that some change in conditions forced an early 

 monkey-like animal that lived on the ground to escape from its enemies by 

 climbing trees. This arboreal habit was so useful to him that he continued 

 it during his life, and his offspring, being from birth kept in the trees, acquired 

 the same habit. Now it would be sure to follow that the new method of 

 using their muscles would soon adapt them more closely to the duty of climb- 

 ing. Changes in the development of different parts of the body would in- 

 evitably occur as the direct result of the new environment, and they would 

 all be acquired characters. The children would develop the same muscles, 

 tendons, and bones, since they, too, lived in the trees and had the same influ- 

 ences acting upon them. Such acquired characters would enable the ani- 

 mals to live in the trees, and would thus determine which individuals should 

 survive in the struggle for existence, for those modified individuals would 

 clearly have the advantage over those that stayed on the ground, or did not 

 become properly adapted to arboreal life by acquired habits. All this would 

 take place without any necessity for a congenital variation or the inheritance 

 of any character which especially adapted the monkey for life in the trees. 



"But in the monkeys thus preserved, congenital variations would be ever 



1 The Method of Evolution, p. 308 et seq. 

 O 



