262 SEXUAL SELECTION: MAMMALS. [Part IL 



old do not roar or hollow ; and that the old ones hegin 

 bellowing at the commencement of the breeding-season, 

 at first only occasionally and moderately, while they rest- 

 lessly wander about in search of the females. Their bat- 

 tles are prefaced by lond and prolonged bellowing, but 

 during the actual conflict they ai'e silent. Animals of all 

 kinds which habitually use their voices, utter various 

 noises under any strong emotion, as when enraged and 

 preparing to fight ; but this may merely be the result of 

 their nervous excitement, which leads to the spasmodic 

 contraction of almost all the muscles of the body, as when 

 a man grinds his teeth and clinches his hands in rage or 

 agony. No doubt stags challenge each other to mortal 

 combat by bellowing ; but it is not likely that this habit 

 could have led through sexual selection, that is, by the 

 loudest-voiced males having been the most successful in 

 their conflicts, to the periodical enlargement of the vocal 

 organs ; for the stags with the most powerful voices, unless 

 at the same time the strongest, best-armed, and most coura- 

 geous, would not have gained any advantage over their 

 rivals with weaker voices. The stags, moreover, which 

 had weaker voices, though not so well able to challenge 

 other stags, would have been drawn to the place of com- 

 bat as certainly as those with sti'onger voices. 



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

 some actual service to him in striking terror into his ad- 

 versary ; for when enraged he likewise erects his mane 

 and thus instinctively tries to make himself appear as ter- 

 rible as possible. But it can hardly be supposed that the 

 bellowing of the stag, even if it be of any service to liira 

 in this way, can have been important enough to have led 

 to the periodical enlargement of the throat. Some writ- 

 ers suggest that the bellowing serves as a call to the fe- 

 male ; but the experienced observers above quoted inform 

 me that female deer do not search for the male, though 



