SEXUAL SELECTION 595 



life as in the male. In the male of an Indian paroquet 

 {Palceornis j'avanicus) the upper mandible is coral red from 

 his earliest youth, but in the female, as Mr. Blyth has ob- 

 served with caged and wild birds, it is at first black and 

 does not become red until the bird is at least a year old, 

 at which age the sexes resemble each other in all respects. 

 Both sexes of the wild turkey are ultimately furnished with 

 a tuft of bristles on the breast, but in two-year-old birds 

 the tuft is about four inches long in the male and hardly 

 apparent in the female; when, however, the latter has 

 reached her fourth year, it is from four to five inches 

 in length." 



These cases must not be confounded with those where 

 diseased or old females abnormally assume masculine char- 

 acters, nor with those where fertile females, while young, 

 acquire the characters of the male, through variation or 

 some unknown cause." But all these cases have so much 

 in common that they depend, according to the hypothesis 

 of pangenesis, on gemmules derived from each part of the 

 male being present, though latent, in the female ; their de- 

 velopment following on some slight change in the elective 

 affinities of her constituent tissues. 



A few words must be added on changes of plumage in 

 relation to the season of the year. From reasons formerly 

 assigned there can be little doubt that the elegant plumes, 

 long pendent feathers, crests, etc., of egrets, herons, and 



*' On Ardetta, Translation of Ouvier's "B^gne Animal," by Mr. Blyth, 

 footnote, p. 159. On the Peregrine Falcon, Mr. Blyth, in Charlesworlh's 

 "Mag. of Nat. Hist.," vol. i., 1837, p. 304. On Dicrurua, "Ibis," 1863, p. 44. 

 On the Platalea, "Ibis," vol. vi., 1864, p. 366. On the BombyciUa, Audubon's 

 "Ornithol. Biography," vol. i. p. 229. On the Palseomls, see also Jerdon, 

 "Birds of India," vol. i. p. 263. On the wild turkey, Audubon, ibid., vol. 1. 

 p. 15; but I hear from Judge Oaton that in Illinois the female very rarely 

 acquires a tuft. Analogous cases with the females of Petrocossyphus are 

 given by Mr. E. B. Sharpe, "Proc. Zoolog. Soc," 1872, p. 496. 



2' Of these latter cases Mr. Blyth has recorded (Translation of Cuvier'a 

 "E^gne Animal," p. 158) various instances with Lanius, Euticilla, Linaria, 

 and Anas. Audubon has also recorded a similar case ("Ornith. Biog.," voL v. 

 p. 519) with Lyranga cestiva. 



