C «A1>. VIII. 
SEXUAL SELECTION. 
293 
°Ur rule; for it is generally caused by intemperance 
after early youth, and is transmitted from the father 
t° his sons in a much more marked manner than to his 
daughters. 
Iu the various domestic breeds of sheep, goats, and 
battle, the males differ from their respective females 
m the shape or development of their horns, forehead, . 
mane, dewlap, tail, and hump on the shoulders; and 
fliese peculiarities, in accordance with our rule, are not 
fully developed until rather late in life. With dogs, 
Hie sexes do not differ, except that in certain breeds, 
especially in the Scotch deer-hound, the male is much 
Wger and heavier than the female ; and as we shall see 
m a future chapter, the male goes on increasing in size 
f° an unusually late period of life, which will account, 
^cording to our rule, for his increased size being trans- 
mitted to his male offspring alone. On the other hand, 
file tortoise-shell colour of the hair, which is confined 
f° female cats, is quite distinct at birth, and this case 
^elates our rule. There is a breed of pigeons in which 
flic males alone are streaked with black, and the streaks 
Ca n be detected even in the nestlings ; but they become 
more conspicuous at each successive moult, so that this 
c ase parti v opposes and partly supports the rule. \\ itli 
file English Carrier and Pouter pigeon the full develop- 
ment of the wattle and the crop occurs rather late in 
fife, and these characters, conformably with our rule, 
m® transmitted in full perfection to the males alone, 
•file following cases perhaps come within the class pre- 
viously alluded to, iu which the two sexes have varied 
m the same manner at a rather late period of life, and 
hiive consequently transferred their new characters to 
f^-th sexes at a corresponding late period ; and if so, 
SU( 'h cases are not opposed to onr rule. Thus there 
ai 'e sub-breeds of the pigeon, described by Neumeis- 
