This assumption has however no basis in fact, for the most superficial consideration will show how profoundly women can be changed by their environ­ ment. Not only do the women of the same race exhibit great differences from time to time in regard to the complex social instincts and virtues, but even their more elemental sexual and maternal instincts are subject to modification. While in extreme cases the sexual impulses are liable to perversion, it some­ times happens that the maternal instinct disappears altogether, and women neglect or, like a tigress in captivity, may even destroy their young.