Chap. VIII. 
SEXUAL SELECTION. 
299 
°f and accumulated through sexual selection in rela- 
tion to the reproduction of the species ; therefore it 
appears, at first sight, an unaccountable fact that simi- 
lar variations have not frequently been accumulated 
through natural selection, in relation to ordinary habits 
°f life. If this had occurred, the two sexes would fre- 
quently have been differently modified, for the sake, 
h>r instance, of capturing prey or of escaping from 
danger. "We have already seen and shall hereatter 
Uieet with other instances of differences of this kind 
between the two sexes, especially with the lower ani- 
mals; hut they are rare in the higher classes. We 
should, however, bear in mind that the sexes in the 
higher classes generally follow the same habits of life; 
and supposing that the males alone varied in a manner 
favouring their power of gaining subsistence, &c., and 
transmitted such variations to their male offspring 
alone, these would acquire an organization superior to 
that of the females ; but it is probable that the females, 
h'oru having the same general constitution and iroin 
being exposed to the same conditions, would sooner or 
later vary in the same manner ; and as soon as this 
°ccurred, the variations would he equally preserved 
through natural selection in the two sexes, which would 
thus ultimately become like each other, lhe case is 
widely different with variations accumulated through 
^xual selection; for the habits of the two sexes in 
tclation to the reproductive functions are not the same, 
Hll d sexually-transmitted modifications serviceable to 
the one sex would in it be preserved, whilst similar 
^edifications would often be quite useless to the other 
8e x, and consequently would in this latter soon be lost. 
In the following chapters, I shall treat of the 
secondary sexual characters in animals of all classes, 
