DEVELOPMENT OF BEHAVIOR ?> 2 1 



The fact is established that organisms which vary in such a way as 

 to make them unfitted to carry out the functions which they undertake 

 are destroyed. The correlative fact that organisms which vary in such 

 a way as to perform their functions better than the average are not so 

 usually destroyed, is likewise established. The further fact is established 

 that such congenital variations occur and are often handed on to the off- 

 spring. These three facts show that natural selection is beyond ques- 

 tion a factor in the development of behavior. The only question is as 

 to the extent of its agency. This depends on the number and extent 

 of the congenital variations that occur. If these are sufficiently numer- 

 ous and sufficiently varied, then it seems clear that natural selection 

 guided by individual accommodation, would produce the results which we 

 see. Its method of action is exactly what is needed to produce the ob- 

 served results; the only question is whether the material presented to 

 it in congenital variations is sufficient. The answer to this question 

 must come, if it ever comes, from that study of variations which has 

 received such an impulse in recent years. The recent studies of De 

 Vries in mutation seem especially promising from this point of view. If 

 it should appear that the material presented by congenital variations is 

 not sufficient to account for the observed development, we should be 

 forced apparently to turn once more to the possibility of the inheritance 

 of the characteristics developed during the lifetime of the organism. 

 The question of the inheritance of acquired characters cannot as yet be 

 considered finally settled. 



The view that the development of behavior is based largely on selec- 

 tion from among varied movements, with subsequent retention of the 

 selected movements, to which we have come through a study of the be- 

 havior of the lower organisms, is of course not a new one. A theory 

 to this effect has been set forth by Spencer and Bain, and has been 

 especially developed in recent years by J. Mark Baldwin. The obser- 

 vations set forth in the present work lead to views differing in some 

 important respects from these developed by Baldwin and Bain, par- 

 ticularly as to the nature of the causes which produce the varied move- 

 ments. Space will not permit our entering here into a discussion of 

 these differences. The reader may be referred for a discussion of some 

 of the general bearings of this theory to the two volumes of Baldwin 

 (1897, 1902). Possibly the most lucid statement of this theory, in its 

 general bearings, is that recently given by Hobhouse (1901). 



LITERATURE XIX 



Baldwin. 1897, 1902; Hobhouse, 1901 : Spencer, 1894 (Section 236. pp. 244' 

 245) ; Bain, 1888 (p. 315) : 1894 (pp. 323. 324). 



