226 GORILLAS AND CHIMPANZEES 



frequently made the same sound at night. It was 

 said to be so loud and piercing that it fairly shook 

 the stately walls of Madison Square Garden. 

 From reading the description given by the late 

 Professor Romanes of the sound made by Sally " 

 in the London Gardens, it appears to be the same 

 sound. 



It is well known to the natives that the chim- 

 panzees beat on some sonorous body, which they call 

 a drum. Four years ago I called attention to the 

 habit of the two chimpanzees in the Cincinnati 

 Gardens. They frequently indulged in beating upon 

 the floor of their cage with their knuckles. This 

 was done chiefly by the male. The late E. J. 

 Glave described to me the same thing, as being 

 done by the chimpanzees in the Middle Congo 

 basin. 



It is not probable that two animals of different 

 genera utter the same exact sound, and this is more 

 especially true of a sound that is complex or pro- 

 longed. Neither is it likely that the two would 

 have a common habit, such as beating on any 

 sonorous body. Since it is certain that one of these 

 apes does make the sound described, it is more than 

 probable that the other does not. The same logic 

 applies to the beating. 



Many things that are known of the chimpanzee 

 are taken for granted in the gorilla, but it is erroneous 

 to suppose that in such habits as these they would 

 be identical. In some cases I have been able to 

 prove quite conclusively that the chimpanzee alone 



