[148]

p. 299D

As(Variations occurring late in life & transmitted to one sex alone have so often incessantly been taken advantage of & accumulated through sexual selection in relation to the reproduction of the species; therefore it appears at first sight an unaccountable fact that similar variations have not any frequently been accumulated through natural selection in relation to the ordinary habits of life of species. If this had occurred the two sexes would often frequently have been become differently modified, for the sake, for instance, of capturing prey or escaping from danger. We have already seen & shall hereafter meet with other instances of differences of this kind between the two sexes, especially with the lower animals; but they are rare in the higher classes. We should, however, bear in mind that the twosexes in the higher classes generally follow the same habits of life; 

[148v]

Scrap used in the Reprint of Descent of Man (30)

(2

D continued p. 299)

& supposing that the males alone were to vary at a later age varied in a manner favouring their power of gaining subsistence &c, & transmitted such variations to their male offspring alone, these would become better constructed than acquire a superior organisation to that of the females; but it is probable that the females, from having the same general constitution & from being exposed to the same conditions, would sooner or later vary in the same manner as the males; & as soon as this occurred the variations would be equally be preserved through natural selection in both the two sexes, which would thus ultimately become like each other. The case is widely different with variations accumulated through sexual selection in relation to the reproductive functions; for the habits of the two sexes are not the same in relation to the reproduction functions, this

respect, & any sexually limited transmitted modifications which were serviceable to the one sex would be preserved, whilst similar modification would generally often be quite useless to the other sex, & would consequently as lately remarked, would soon be lost.)

(If necessary one line open might here be left)