MENTAL LIFE OF MONKEYS AND APES 3 



valuable. The former aided me most intelligently in the care 

 of the animals and the construction of apparatus; and the latter, 

 especiall3% was of very real service in connection with many of 

 my experiments. 



The collection of animals which Doctor Hamilton placed at 

 my disposal consisted of ten monkeys and one orang utan. 

 The monkeys represented either Pithecus rhesus Audebert 

 {Macacus rhesus), Pithecus irus F. Cuvier {Macaciis cynomolgos), 

 or the hybrid of these two species (Elliot, 1913). There were 

 two eunuchs, five males, and three females. All were thoroughly 

 acclimated, having lived in Montecito either from birth or for 

 several years. The orang utan was a young specimen of Pongo 

 pygmcEus Hoppius obtained from a San Francisco dealer in 

 October, 1914 for my use. His age at that time, as judged by 

 his size and the presence of milk teeth, was not more than five 

 years. So far as I could discover, he was a perfectly normal, 

 healthy, and active individual. On June 10, 1915, his weight 

 was thirty-four pounds, his height thirty-two inches, and his 

 chest girt twenty-three inches. On August 18 of the same 

 year, the three measurements were thirty-six and one-half 

 pounds, thirty-three inches, and twenty-five inches. 



For the major portion of my experimental work, only three 

 of the eleven animals were used. A growing male, P. rhesus 

 monkey, known as Sobke; a mature male, P. irus, called Skirrl; 

 and the young orang utan, which had been named Julius. Plates 

 I and n present these three subjects of my experiments in char- 

 acteristically interesting attitudes. In plate I, figure 1, Julius 

 appears immediately behind the laboratory seated on a rock, 

 against a background of live oaks. This figure gives one an 

 excellent idea of the immediate environment of the laboratory. 

 Figure 2 of the same plate is a portrait of Julius taken in the 

 latter part of August. By reason of the heavy growth of hair, 

 he appeared considerably older as well as larger at this time 

 than when the photograph for figure 1 was taken. In plate II, 

 figure 3, Julius is shown in the woods in the attitude of reaching 

 for a banana, while in figure -i of the same plate he is represented 

 as walking upright in one of the cages. 



Likenesses of Sobke are presented in figures 5 and 6 of plate 

 II. In the latter of these figures he is shown stretching his 

 mouth, apparently yawning but actually preparing for an attack 



