220 GORILLAS AND CHIMPANZEES 



gorilla closes the hand to strike, nor uses any weapon 

 except the hands and teeth. I had another young 

 female gorilla for a short time as a subject for study. 

 Her mode of attack appeared to be the same, but 

 she was too large to risk in such experiments. 



I have read and heard descriptions of the sounds 

 made by the gorilla, but nothing ever conveyed 

 to my mind an adequate idea of their true nature, 

 until I heard them myself within a few hundred 

 feet of my cage in the dead of night. By some it 

 has been called roaring, and by others howling ; 

 but it is neither truly a roar nor a howl. They 

 utter a peculiar combination of sounds, beginning 

 in a low, smooth tone, which rapidly increases 

 in pitch and frequency, until it becomes a terrific 

 scream. The first part of the series is quite within 

 the scope of the human voice, but as it rises in pitch 

 and increases in volume it passes far beyond the 

 reach of the human lungs. The first sound of the 

 series and each alternate sound is made by expira- 

 tion, while the intermediate ones appear to be by 

 inspiration, but how it is accomplished is difficult to 

 say. The sound as a whole resembles the braying 

 of an ass, except the notes are shorter, the climax 

 higher, and the sound is louder. A gorilla does not 

 yell in this manner every night, but when he does so 

 it is usually betw^een two and five o'clock in the 

 morning ; I have never heard the sound during the 

 day nor in the early part of the night. When he 

 thus screams, he repeats the series from ten to 

 twenty times, at intervals of one or two minutes each. 



