274 Dr Mehliss on Virilesceiice, 



power of generation has been lost, and in which the sexual dif- 

 ferences are sufficiently strongly marked, not merely in the or- 

 gans of generation themselves, but in other parts of the frame. 

 Consequently, it cannot occur in vegetables ; for the difference 

 of sex is here only marked in the sexual organs themselves. 

 Kob, indeed, has compared the regular metamorphoses of the 

 organs of generation of plants into other parts (as, for instance, 

 of styles into stamens, and the occurrence of male blossoms on 

 the female plants of the class Dioecia), with the appearance of 

 virilescence in animals ; but these deviations from the normal 

 condition are original, and do not admit of comparison with the 

 animal phenomena, which distinctly require the complete de- 

 velopment of the sexual character at a former period of life. 

 This condition is fulfilled only in the more perfect animals — 

 in birds, in the mammalia, and in man. In insects, the sexual 

 difference is sufficiently clearly marked in the external confor- 

 mation of their bodies ; but their life, closing with the process 

 of generation, is too short to exhibit the phenomena of viriles- 

 cence. In some of the Crustacea, in fish, and in amphibia, 

 observation will probably yet detect the existence of these 

 changes. In all animals, however, and under all circumstances, 

 virilescence is extremely rare. 



In birds, the chief distinction between the sexes, after the 

 differences between the parts of generation, consists in the plu- 

 mage, which is more developed, and possesses more lively and 

 varied colours, in the male than in the female. The size of the 

 body, the character of the voice, and the occurrence of spurs 

 on the feet, establish other, but less striking, distinctive marks. 

 In each of these particulars, the female bird may simulate the 

 outward appearance of the male, and to such an extent that a 

 careful observation shall scarcely distinguish the sexes. Our 

 author collects abundant proof of this fact from undoubted 

 authorities : of these, the greater part occurred in the domes- 

 tic fowl and common pheasant ; others in other species of phea- 

 sant, in the turkey, peacock, and common duck. The par- 

 tridge, wood-pigeon, starling, bustard, chaffinch, and four or 

 five other birds, have been observed to assume the same pecu- 

 liarities. The change of plumage was the most remarkable, as 

 well as by far the most frequent, phenomenon ; the alteration 



