I do not wish to call in question the utility of observations, or to pretend that they must be neglected. I only wish to say that in attaching to them too much consequence we are led to false conclusions which may inspire a dangerous security. The physician who commits this fault, reasons as does the onanist, who being unable to distinguish, either in his comrades or in himself, the effects of his pernicious habit, concludes that it is an innocent practice and that it may be indulged in unreservedly. The principal utility of observing the diseases caused by masturbation is to determine _what are the maladies produced by onanism and what is the relative frequency of each of them_. We can also certainly form an opinion, from that which is shown by observation, in regard to that which escapes us. But it is only by induction, that the extent of the evils caused by venereal abuses can be estimated. The bad effects produced by these abuses, can be estimated only by considering what they may produce. It is only after studying the genital system in its relations with other organs, and considering the influence it exercises upon them, that we can pronounce in regard to the maladies and infirmities and dangers of all kinds which attend the abuse of the genital system. We proceed to this subject first. We shall then state what is known from direct observation in regard to the different affections which result from venereal excesses. CHAPTER I. OF THE DANGERS WHICH MAY FOLLOW VENEREAL EXCESS. To abuse oneself by onanism, by coition, is to abuse the organs which serve for the execution of these acts. The genital organs in the female are, the vulva, clitoris, vagina, uterus, fallopian tubes and ovaries. Those in the male are the penis, the seminal passages and the testicles. These organs are then placed in such a state that they become a source of disorder and of disease to the rest of the body. Now, what is their power in this respect? Can they do much injury? This is the question now to be examined.