28 Studies in Animal Behavior 



was foreshadowed by the different degrees of im- 

 portance attached by Darwin and Spencer to the 

 factors of natural selection and the transmission of 

 acquired characters. Darwin accepted the latter the- 

 ory, but assigned to the Lamarckian factor a subor- 

 dinate role as compared with natural selection. Spen- 

 cer, who had already elaborated his system of psy- 

 chology on the basis of the Lamarckian theory, 

 naturally attached great weight to that doctrine, but 

 when the theory of natural selection was announced 

 he cordially received it, but he appealed to it mainly 

 as a helpful subsidiary hypothesis. 



Since Weismann made his attack upon the La- 

 marckian theory he has been followed by a consider- 

 able number of psychologists, such as Lloyd Morgan, 

 Forel, Groos, Whitman, Baldwin and Zeigler, who 

 reject entirely the doctrine that acquired characters 

 are transmitted. Among the neo-Lamarckians who, 

 though somewhat in the minority, still represent a 

 flourishing school, there are all sorts of views re- 

 garding the potency of natural selection, some writ- 

 ers going so far as to cast the theory aside as a 

 visionary and groundless speculation. Romanes, 

 Eimer, Haeckel, Hering, Wundt, Cope, Semon and 

 Pauly are among the principal writers of this school 

 who have concerned themselves with comparative 

 psychology. The combination of vitalism and La- 

 marckism which is presented in the writings of Pauly 

 and France affords, in the opinion of its adherents, 

 a method of accounting for the development of 



