MISCELLANEOUS OBSERVATIONS 



1. Right- and lejt-handedness 



Several years ago Doctor Hamilton reported to me observa- 

 tions which he had made on preference for the right or left paw 

 in dogs. He has not, I believe, published an account of his 

 work. Subsequently, Franz observed a similar preference in 

 monkeys which, according to his report, exhibit marked tendency 

 to be right-handed, left-handed, or ambidextrous. 



My own observations, although they are wholly incidental to 

 my other work, seem worthy of description at this point. 



I noted, first of all, that the orang utan Julius tended to use 

 his left hand. He by no means limited himself to this, but 

 in difficult situations he almost invariably reached for food or 

 manipulated objects in connection with food getting with the 

 left hand. Figures 23 and 24 of plate V, show him reaching 

 for a banana with the left hand. Likewise, figure 34 exhibits 

 the use of the left hand in the draw-in experiment. 



So marked was Julius's preference for his left hand that I 

 became interested in observing similar phenomena in the monkeys. 



Skirrl, when driving nails, held the hammer with his left 

 hand and the nail with his right hand. The fact that he never 

 was observed to reverse the use of the hands is surprising, for 

 other observations indicate that he preferred the right hand 

 for certain acts. 



Stimulated by the obvious left-handedness, in certain con- 

 nections, of Julius and Skirrl, I tested the preference of several 

 of the monkeys in the following simple way. Standing outside 

 the cage I would hold out a peanut to a hungry animal, keeping 

 it so far from the cage that the monkey could barely reach it 

 with its fingers. I noted the hand which was used to grasp the 

 food. Next I varied the procedure by placing the peanut on 

 a board in order to make sure that I was not definitely directing 

 the animal's attention. 



