52a THE DESCENT OF MAN. 



but this may merely be the result of nervous excitement, which 

 leads to the spasmodic contraction of almost all the muscles of 

 the body, as when a man grinds his teeth and clenches his fists 

 in rage or agony. No doubt stags challenge each other to mortal 

 combat by bellowing; but those with the more powerful voices, 

 unless at the same time the stronger, better-armed, and more 

 courageous, would not gain any advantage over their rivals. 



It is possible that the roaring of the lion may be of some 

 service to him by striking terror into his adversary; for when 

 enraged he likewise erects his mane and thus instinctively tries 

 to make himself appear as terrible as possible. But it can hardly 

 be supposed that the bellowing of the stag, even if it be of ser- 

 vice to him in this way, can have been important enough to have 

 led to the periodical enlargement of the throat. Some writers 

 suggest that the bellowing serves as a call to the female; but the 

 experienced observers above quoted inform me that female deer 

 do not search for the male, though the males search eagerly for 

 the females as indeed might be expected from what we know of 

 the habits of other male quadrupeds. The voice of the female, 

 on the other hand, quickly brings to her one or more stags,' as is 

 v/ell known to the hunters who in wild countries imitate her cry. 

 If we could believe that the male had the power to excite or 

 allure the female by his voice, the periodical enlargement of his 

 vocal organs would be intelligible on the principle of sexual selec- 

 tion, together with inheritance limited to the same sex and season; 

 but we have no evidence in favor of this view. As the case 

 stands, the loud voice of a stag during the breeding-season does 

 not seem to be of any special service to him, either during his 

 courtship or battles, or in any other way. But may we not be- 

 lieve that the frequent use of the voice, under the strong excite- 

 ment of love, jealousy, and rage, continued during many genera- 

 tions, may at last have produced an inherited effect on, the vocal 

 organs of the stag, as well as of other male animals'? This ap- 

 pears to me, in our present state of knowledge, the most prob- 

 able view. 



The voice of the adult male gorilla is tremendous, and he is 

 furnished with a laryngeal sack, as is the adult male orang.* 

 The gibbons rank among the noisiest of monkeys, and the Suma- 

 tra species (Hylobates syndactylus) is also furnishec" with an air 

 sack; but Mr. Blyth, who has had opportunities for observation, 

 does not believe that the male is noisier than the female. Hence, 

 these latter monkeys probably use their voices as a mutual call; 

 and this is certainly the case with some quadrupeds, for Instance 



= See, for instance, Major W. Ross King- ('The Sportsman in Canada,' 

 1S66, p. 53, 131) on the habits of the moose and wild reindeer. 

 * Owen, 'Anatomy of Vertebrates,' vol. iii. p. 600. 



