SEXUAL SELECTION 685 



only a conjectural and unsatisfactory explanation of its 

 use." 



In most cases, when only the male emits a strong odor 

 during the breeding season, it probably serves to excite or 

 allure the female. We must not judge on this head by our 

 own taste, for it is well known that rats are enticed by cer- 

 tain essential oils, and cats by valerian, substances far from 

 agreeable to us ; and that dogs, though they will not eat car- 

 rion, sniff and roll on it. From the reasons given when dis- 

 cussing the voice of the stag, we may reject the idea that 

 the odor serves to bring the females from a distance to the 

 males. Active and long-continued use cannot here have 

 come into play, as in the case of the vocal organs. The 

 odor emitted must be of considerable importance to the 

 male, inasmuch as large and complex glands, furnished 

 with muscles for everting the sac, and for closing or 

 opening the orifice, have in some cases been developed. 

 The development of these organs is intelligible through 

 sexual selection, if the most odoriferous males are the 

 most successful in winning the females, and leaving off- 

 spring to inherit their gradually perfected glands and 

 odors. 



Development of the Hair. — We have seen that male 

 quadrupeds often have the hair on their necks and shoul- 

 ders much more developed than the females; and many 

 additional instances could be given. This sometimes 

 serves as a defence to the male during his battles; but 

 whether the hair in most cases has been specially devel- 

 oped for this purpose is very doubtful. We may feel al- 

 most certain that this is not the case when only a thin and 

 narrow crest runs along the back; for a crest of this kind 

 would afford scarcely any protection, and the ridge of the 

 back is not a place likely to be injured; nevertheless, sach 



'» P&Kas, "Spioile^ Zoolog.," fasc. xiii., 1799, p. 24; DesmooHna, "Dfcst 

 Class, d'ffist Wat," torn. iH. p. 586. 



