Heredity may be briefly designated as the sum of those qualities which our fore parents possessed, transmitted to us, and reproduced in such modifications as are determined by our environments. Weiss-man calls it "a property of an organism by which its particular nature is transmitted to its descendants;" and Ribot tersely defines it as "the tendency of a being to reproduce itself in its progeny." These terms and phrases mean little, however, save as a cloak for our absolute ignorance. The truth is, as I have previously stated, the mystery involved in the subtle, and seemingly interminable synthetic processes by which "like produces like " being so impenetrable as to afford little satisfaction to the biological reasoner, and is only dwelt upon here on account of its intimate association with sexual perversion, from which sexual crime almost invariably springs.