Sexuality in the child, as I have said, may be considered as generis neutrius; and it is precisely at this point, when psychical desire has not yet reached out toward its natural opposite of sex, when it is, as it were, trembling in the balance, that some accidental or designed excitation of the genitals, or the mind, may lead it into abnormal channels, developing either masturbation or acquired homosexuality. The differentiation of the sexual instinct goes hand in hand with those anatomical and morphological changes which produce sex itself; and the course of the rudimentary mental impulse, even more than that of physical growth, is affected powerfully by these external educational influences which might pass unnoticed at a later period of life, when the receptivity of the individual would be less keenly alive.

If the constitution, ab origine, be normal, the psycho-sexual development is likely to be also normal; but if any weakness or susceptibility exist in the prenatal lines of defence, and that weakness be subjected to the diverting influences mentioned, parccsthe&ia sexualis is very likely to result, and with it contrary sexual desire.