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Show 280 SEXUAL SELECTION: MA1\1MALS. PART If_ trated whilst young never emits it,1° Besides the general odour, with which the whole body of certain ruminant:-; seems to be permeated during the breeding-season, many deer, ante lopes, sheep, and goats, possess odoriferous glands in various situations, more especially on their faces. The so-called tear-sachs or suborbital pits come under this head. These glands secrete a semi-fluid fetid matter, which is sometimes so copious as to stain the whole face, as I have seen in the case of an antelope. They are "usually larger in the male than in " the female, and their development is checked by cas" tration." 11 According to Desmarest they arc altogether absent in the female of Antilope subgutturosa. Hence, there can bs no rloubt that they stand in some close relation with the reproductive functions. 'rbey are also sometimes present, and sometimes absent, in nearly-allied forms. In the adult" male musk-deer ( Moschus moschiferus), a naked space round the tail is bedewed with an odoriferous fluid, whilst in tho adult female, and in the male, until two years old, this space is covered with hair and is not odoriferous. The proper musk-sack, from its position, is necessarily confined to the male, and forms an additional scent-organ. It is a singular fact that the matter secreted by this latter gland does not, according to Pallas, change in consistence, or increase in quantity, dming the ruttingseason; nevertheless this naturalist admits that its presence is in some way connected with the act of repro- 10 Rcnggcr, • Naturge ·chiohte <ler Siiugcthiere von Paraguay,' 1 8:~0, s. i.l55. 'fhis observer also gives some curious particulars in regard to the odour emitted. u Owen, 'Anatomy of Vertebrate ,' vol. iii. p. 632. Sec, also, Dr. Murie's observations on their glands in 'Proc. Zoolog. Soc.' 1870, p. iHO. Desmarest, On the Anlilope subgutlttrosct, • Mamm11logie,' 1820, p. 4.55. CHAP. XVIII. DEVELOPMENT OF HATH. 281 duction. He gives, however, only a conjectural and unsatisfactory explanation of its use.12 In most cases, when during the breeding-season the male alone emits a strong odour, this probably serves to excite or allure the female. We must not judge un this head by our own ta te, for it is well known that rats are enticed by certain essential oils, and cats by valerian, substances which are far from agreeable to us ; and that dogs, though they will not eat carrion, sniff and roll in it. From the reasons given when discussing the voice of the stag, \\'e may reject the idea that the odour 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 odour emitted must be of considerable importance to the male, inasmuch as large and complex glands, furnished with muscles foL· everting the sack, and for closing or opening the 01·ifice, have in some cases been developed. rrhe development of these orQans is intellicrible throuO'h sexual selection . ~ 0 0 ' If the more odoriferous males are the most successful in winning the females, and in leaving offspring to inherit their gradually-perfected glands ancl odours. Development of the Hair.-We have seen that male quadrupeds often have the hair on their necks and shoulders much more developed than in 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 developed for this purpose is very doubtful. We may feel almost certain that this is not the case,. , 1 ~ P11llas, '~Pi.cilegia Zoolog.' fasc. xiii. 1700, p. _24; Desmoulins, D10t. Class. d H1st. Nat.' tom. iii. p. 586. |
