Chap. XIII. 



REVERSION. 



51 



sively from the father or mother, but that many characters lie 

 latent in both parents during a long succession of generations, 

 the foregoing facts are intelligible. In what manner characters 

 may be conceived to lie latent, will be considered in a future 

 chapter to which I have lately alluded. 



Latent Characters.— But I must explain what is meant 

 by characters lying latent. The most obvious illustration is 

 afforded by secondary sexual characters. In every female all 

 the secondary male characters, and in every male all the secondary 

 female characters, apparently exist in a latent state, ready to 

 be evolved under certain conditions. It is well known that a 

 large number of female birds, such as fowls, various pheasants, 

 partridges, peahens, ducks, &c, when old or diseased, or when 

 operated on, partly assume the secondary male characters of 

 their species. In the case of the hen-pheasant this has been 

 observed to occur far more frequently during certain seasons 

 than during others. 51 A duck ten years old has been known to 

 assume both the perfect winter and summer plumage of the 

 drake. 52 Waterton 53 gives a curious case of a hen which had 

 ceased laying, and had assumed the plumage, voice, spurs, and 

 warlike disposition of the cock ; when opposed to an enemy she 

 would erect her hackles and show fight. Thus every character, 

 even to the instinct and manner of fighting, must have lain 

 dormant in this hen as long as her ovaria continued to act. The 

 females of two kinds of deer, when old, have been known to 

 acquire horns; and, as Hunter has remarked, we see something 

 of an analogous nature in the human species. 



On the other hand, with male animals, it is notorious that the 

 secondary sexual characters are more or less completely lost 

 when they are subjected to castration. Thus, if the operation be 

 performed on a young cock, he never, as Yarrell states, crows 



51 Yarrell, ' Phil. Transact.,' 1827, p. 

 268 ; Dr. Hamilton, in < Proc. Zoolo°-' 

 Soc.,' 1862, p. 23. 



52 'Archiv. Skand. Beitrage zur 

 Naturgesch,' viii. s. 397-413. 



53 In his 'Essays on Nat. Hist.,'1838. 

 Mr. Hewitt gives analogous cases with 

 hen-pheasants in 'Journal of Horti- 

 culture,' July 12, 1864, p. 37. Isidore 



Geoffroy Saint Hilaire, in his 'Essais 

 de Zoolog. Gen.' (suites a Buffon, 1842, 

 pp. 496-513), has collected such cases in 

 ten different kinds of birds. It appears 

 that Aristotle was well aware of the 

 change in mental disposition in. old 

 hens. The case of the female dee** 

 acquiring horns is given at p. 513. 



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