30 Studies in Animal Behavior 



not so much with the aim of establishing the fact of 

 evolution in a particular field, as of illuminating 

 the subject in the light of its historical development. 

 In human psychology the genetic method of study 

 is pursued to a large extent in the works of Stanley 

 Hall, Groos and Baldwin, and in the recent volumes 

 of Kirkpatrick on Genetic Psychology and of 

 Parmelee on Human Behavior. Modern "phi- 

 losophy of education" has been influenced in no small 

 degree by studies and speculations in comparative 

 psychology, and especially in this country by those of 

 Stanley Hall and his school. The doctrine of re- 

 capitulation figures quite largely in the writings of 

 this school, and, while the results of its applica- 

 tion have not always been happy, the general influ- 

 ence of Hall and his followers has given a strong 

 stimulus to genetic psychology and the scientific study 

 of problems of education. 



Much attention has been devoted to the experi- 

 mental analysis of instinct. The complex instincts 

 of crustaceans and insects have been shown by means 

 of operative experiments on the nervous system to 

 be, to a large extent at least, capable of analysis 

 into reflex activities of the various segments. A 

 brainless crayfish will walk, eat food, reject innu- 

 tritious substances, defend itself when seized, and 

 perform various other complex activities. When 

 any of the segmental ganglia of the nervous cord 

 are cut off from communication with the others by 

 severing the connectives, the appendages of the cor- 



