RELATIONS OF COMPARATIVE PSYCHOLOGY 705 



assimilation in terms of like modes of behavior in dealing with 

 them, in terms of the similar responses which they evoke. Thus 

 there is an integration of the situations of so-called play and earn- 

 est. But in perceptual process, far as differentiation may be 

 carried, it never reaches the stage of intentional analysis; and, 

 far as integration through assimilation may be carried, it never 

 reaches the level of intentional generalization. These are the re- 

 sults of ideational process. 



It will be noticed that I here lay marked stress on the distinc- 

 tion between perceptual and ideational process. I said at the out- 

 set that comparative and genetic psychology takes its place be- 

 tween biology on the one hand, with its doctrine of values for or- 

 ganic survival, and, on the other hand, such normative sciences 

 as ethics and esthetics, with their doctrines of worth for the ideal 

 life of man. It appears to me that in the relation of biology to 

 psychology the essential point is to grasp the analytic distinction 

 between the instinctive and intelligent factors, and I have there- 

 fore so far mainly dealt with this distinction. But it also appears 

 to me that in the relations of psychology to normative science, 

 the equally essential point is to grasp the distinction between per- 

 ceptual and ideational process. In the study of the higher ranges 

 of animal psychology and of child-life this distinction has scarcely 

 yet received adequate emphasis. 



The study of the mental processes of the higher animals has 

 of late years passed into a new phase. In the first place, it is now 

 realized that, so far from being easy, it is full of peculiar diffi- 

 culties and beset with special snares which entrap the unwary 

 interpreter. In the second place, it is generally admitted that 

 adequate training is required to enable an observer, no matter how 

 accurate and faithful his record of facts may be, to diagnose in- 

 ferentially the psychological conditions of which the facts them- 

 selves are significant. And in the third place, it is recognized that 

 far more is to be gained by the systematic study of the doings of 

 animals under controlled conditions and in test cases, than by 

 the casual observations of credible but often uncritical witnesses. 

 The new phase of the study of animal intelligence is thus char- 

 acterized by experimental research in the hands of those who are 

 trained psychologists, and who are fully aware of the difficulty 

 and delicacy of the task which they undertake. 



We must remember that in the early days of Darwinism, the 

 first business of those who sought to place the conception of men- 

 tal evolution on a secure basis was to establish the basal principle 

 of continuity in the series of mental products; to show that in 

 animals are to be found the germs of all the higher endowments 

 of man; and to abolish all such radical distinctions in kind as were 



