ISO 
SEXUAL SELECTION: BIEDS. 
Part 1 
in 
furnished with a tuft of bristles on the breast, bid ^ 
two-year-old birds the tuft is about four inches lou? 
the male and hardly apparent in the female; 
however, the latter has reached her fourth year, 
from four to five inches in length . 29 
In these cases, the females follow a normal courS® 
it ’ 5 
.a 
development in ultimately becoming like the males ; iU ’, 
such cases must not be confounded with those in , 
diseased or old females assume masculine charad® . 
or with those in which perfectly fertile females,"'^ 1 ", 
young, acquire through variation or some unknown 
the characters of the male . 30 But all these cases 
so much in common that they depend, according t° .. 
hypothesis of pangenesis, on genumdes derived from eil ‘ 
part of the male being present, though latent, in th e 
male ; their development following on some slight elm 11 ' 
in the elective affinities of her constituent tissues. 
A few words must be added on changes of pin 11 ” 1 ', 
in relation to the season of the year. From red® 
formerly assigned there can be little doubt that ^ 
elegant plumes, long pendant feathers, crests, 
egrets, herons, and many other birds, which are 
loped and retained only during the summer, ge ^ 
exclusively for ornamental or nuptial purposes, th° l1 ' 
ft 
- IJ On Ardetta, Translation of Cuvier s 1 Iiiigne Animal,’ by Mr- 
footnote, p. 15‘J. On the Peregrine Falcon, Mr. Blyth, in ^ _ e 
worth’s 1 Mag. of Nat. Hist,.’ V ol. i. 1837, p. 30h On Bicrurus, t liC 
18(13, p. 44. On the Platalea, ‘Ibis,’ vol. vi. 1864, p. 366. u pH 
Bombycilla, Audubon’s ‘ Oruitholog. Biography,’ vol. i. p. 
the PaJioornis, see, also, Jerdon, • Birds of India,’ vol. i- 1’’ V 
On the wild turkey, Audubon, find. vol. i. p. 15: 1 hear from 1 
i. p. 
Caton that iu Illinois the female very rarely acquires a tuft. 
30 Mr. Blyth has recorded (Translation of Cuvier’s 
Ifegue A» # 
p. 158) various instances with Lanius, Buticilla, I, inaria, and 1 ^ 
Audubon has also recorded a similar case (‘ Ornith. Biog.’ vol. v ’’ P‘ 
with Tymnga mstiva. 
