298 DR. A. KEITH ON THE CHIMPANZEES. [Mar. 7, 



acquired no degenerate sexual habits. The sexual state, so far as 

 Mr. Mackay has observed, does not change with the season of the 

 year. Of menstruation in the Grorilla, nothing is known. 



3. The Belationshij) of the Ch{m_panzee to the Gorilla. 



An examination of all the structural systems of the African 

 Anthropoids leads to the inference that the Gorilla is the more 

 primitive of the two forms, and approaches the common parent 

 anthropoid more nearly than the Chimpanzee. The teeth of the 

 Goinlla, individually and collectively, form a complete dentition, a 

 dentition at the very highest point of development ; the teeth of 

 thh Chimpanzee show marked signs of retrogression in development 

 of size and structure. The muscular development and the 

 consequent bony crests for muscular attachment of the Gorilla far 

 surpass those of the Chimpanzee. The muscular development of 

 the adult Chimpanzee represents the system of the adolescent 

 Gorilla. Some of the bodily organs of the Gorilla belong to a 

 simpler and earher primate type than those of the Chimpanzee, 

 But in one point the Chimpanzee evidently represents more 

 nearly the parent form — its limbs and body are more adapted for 

 arboreal locomotion ; of the two, the Gorilla shows the nearer 

 approach to the human manner of locomotion. On the Avhole, the 

 evidence at our disposal at the present time points to the fact that 

 the Chimpanzee is a Gorilline derivative, in which, with a 

 progressive brain-development, there have been retrograde changes 

 in most of the other parts of the body. The various forms of 

 Chimpanzee differ according to the degree to which these changes 

 have proceeded. 



4. The Brain-development in the Chimpanzees and Gonlla. 



The temperament of the Gorilla and Chimpanzee is absolutely 

 different. All the Gorillas of which we have any knowledge agree 

 in being sullen, untamable, and ferocious, even the youngest of 

 them. They do not tolerate confinement : only one has lived over 

 a year in captivity in Europe ; one is said to have been in the 

 possession of an African chief for six years. The Chimpanzee, 

 on the other hand, at any rate in its younger stages, takes to 

 confinement easily, is teachable and playful. The elaborate toilet 

 and performance gone through daily by " Johanna," the skilful 

 way in which she decants her glass of wine, removing and replacing 

 the stopper, declares her to be a Chimpanzee more clearly than 

 any other character she could show. Her education is probably 

 the most elaborate ever possessed by any ape. She appears to be 

 colour-blind. 



Du Chaillu states that the Chimpanzee to which he gives the 

 name of T. hooloo-lcamba had a distinctive cry ; from her physical 

 features " Johanna " appears to belong to that species. When in 

 a fit of passion, into which she is easily thrown, the hair of the 

 scalp becomes erect, she beats the floor with her feet and hands, 



