Allen, Association in the Guinea Pig. 297 



Animals with complex psychical processes have been 

 studied more extensively than the lowest forms, and the work 

 done here comprises the principal literature in animal psychol- 

 ogy. The classical treatises of Principal Lloyd Morgan are 

 the model and the stimulus for all subsequent investigation. A 

 recent book of his, "Animal Behavior," contains summaries 

 and critical notes of all new literature on animal psychology, 

 and a timely discussion of the current conceptions and hypo- 

 theses. 



Morgan, who has worked with chicks especially, finds 

 memory, intelligent adaptations and a considerable discrimina- 

 tion of objects among birds. Besides the numerous researches 

 upon the chick, few other birds have been observed with re- 

 spect to their psychical processes. 



Wesley Mills ' is among the pioneers in the field of ex- 

 perimental psychology. His observations upon a large number 

 of animals, and suggestions concerning the correlation between 

 physical and psychical development, are of especial value as 

 recognizing the problems and methods of most recent investi- 

 gations. 



The employment of the laboratory method of observation 

 and experimentation has led to fruitful results in that, as condi- 

 tions are known and controllable, explanations of given reac- 

 tions may be made with a greater degree of assurance. 



Thokndike has given explicit and clear-cut formulation to 

 the method of experimentation with animals. His free-and-easy 

 psychological terminology, with his desire for a severely scien- 

 tific interpretation of results, as well as unusual confidence in 

 the meaning of facts observed, stimulate competition, not to say 

 contradiction. My work on the guinea pig has been under- 

 taken from a point of view somewhat similar to that assumed 

 by Thorndike; viz., the point of view that the law of parsi- 

 mony must govern interpretation, and a sufficient number of 

 control experiments must condition every statement made. 

 Reference will be made to specific points of Thorndike's work 

 as occasion arises. 



' Mills. The Nature and Development of Animal Intelligence, 1S98. 



[ 5] 



