MENTAL LIFE OF MONKEYS AND APES 131 



Origin of Species," and other works, by Romanes (1900),- especi- 

 ally in his books on mental evolution, by C. Lloyd Morgan 

 (1906) in his several works on comparative psychology, and by 

 Holmes (1911) in his discussion of the evolution of intelligence, 

 contribute not unimportantly to our all too meagre knowledge 

 of the mental life of the anthropoid apes. 



My own results, viewed in the light of what one may learn 

 from the literature, stand out as unique because of the method 

 of research. Never before, so far as I have been able to learn, 

 h'as any ape been subjected to observation under systematically 

 controlled conditions for so long a period as six months. More- 

 over, my multiple-choice method has the merit of having yielded 

 the first curve of learning for an anthropoid ape. This fact 

 is especially interesting when one considers the nature of the 

 particular curve. For so far as one may say by comparing it 

 with the curves for various learning processes exhibited by other 

 mammals, it is indicative of ideation of a high order, and possibly 

 of reasoning. I do not wish to exag'gerate the importance of 

 my results, for as contrasted with what might be obtained by 

 further study, and with what must be obtained if we are ade- 

 quately to describe the mind of the orang utan, they are 

 meager indeed. 



Especially noteworthy, as evidences of ideation, in the results 

 yielded by the multiple-choice method are (1) the_ u.se by t he 

 orang utan of several different methods in connection with each 

 problem ; (2) the suddenness of transition from method/ to meth od ; 

 (3) the final and~perfect soiutien-ef-probiem T'without diminu- 

 tion, of the initial errors; (4) the dissociation of the act of turn- 

 ing in a circle from that of standing" m front ot~arpaTtitnilaP5ox. 



To 'these features of behavior others of minor importance 

 might be added. But as they have been sufficiently empha- 

 sized in the foregoing detailed descriptions, I need only repeat 

 my conclusion, from the summation of evidence, that this young 

 orang utan exhibited numerous free ideas and simple thought 

 processes in connection with the multiple-choice experiment. 

 His ultimate failure to solve the second problem is peculiarly 

 interesting, although in the light of other features of his beha- 

 vior by no means indicative of inferior intelligence. 



The various supplementary experimental tests which I em- 

 ployed are in no wise importantly distinguished from those 



