view implicitly accepted by medieval ascetic writers, who regarded woman as "a temple built over a sewer," and from a very different standpoint it was concisely set forth by Montaigne, who has doubtless contributed greatly to support this view of the matter: "I find," he said, "that Venus, after all, is nothing more than the pleasure of discharging our vessels, just as nature renders pleasurable the discharges from other parts."^[2] Luther, again, always compared the sexual to the excretory impulse, and said that marriage was just as necessary as the emission of urine. Sir Thomas More, also, in the second book of Utopia, referring to the pleasure of evacuation, speaks of that felt "when we do our natural easement, or when we be doing the act of generation." This view would, however, scarcely deserve serious consideration if various distinguished investigators, among whom Féré may be specially mentioned, had not accepted it as the best and most accurate definition of the sexual impulse. "The genesic need may be considered," writes Féré, "as a need of evacuation; the choice is determined by the excitations which render the evacuation more agreeable."^[3] Certain facts observed in the lower animals tend to support this view; it is, therefore, necessary, in the first place, to set forth the main results of observation on this matter. Spallanzani had shown how the male frog during coitus will undergo the most horrible mutilations, even decapitation, and yet resolutely continue the act of intercourse, which lasts from four to ten days, sitting on the back of the female and firmly clasping her with his forelegs. Goltz confirmed Spallanzani's observations and threw new light on the mechanism of the sexual instinct and the sexual act in the frog. By removing various parts of the female frog Goltz found that every part of the female was attractive to the male at pairing time, and that he was not imposed on when parts of a male were substituted. By removing various of the sense-organs of the male Goltz^[4] further found that it was not by any special organ, but by the whole of his sensitive system, that this activity was set in action. If, however, the skin of the arms and of the breast between was removed, no embrace took place; so that the sexual sensations seemed to be exerted through this apparatus. When the testicles were removed the embrace still took place. It could scarcely be said that these observations demonstrated, or in any way indicated, that the sexual impulse is dependent on the need of evacuation. Professor Tarchanoff, of St. Petersburg, however, made an experiment which seemed to be crucial. He took several hundred frogs (Rana temporaria), nearly all in the act of coitus, and in the first place repeated Goltz's experiments. He removed the heart; but this led to no direct or indirect stoppage of coitus, nor did removal of the lungs, parts of the liver, the spleen, the intestines, the stomach, or the kidneys. In the same way even careful removal of both testicles had no result. But on removing the seminal receptacles coitus was immediately or very shortly stopped, and not renewed. Thus, Tarchanoff concluded that in frogs, and possibly therefore in mammals, the seminal receptacles are the starting-point of the centripetal impulse which by reflex action sets in motion the complicated apparatus of sexual activity.^[5] A few years later the question was again taken up by Steinach, of Prague. Granting that Tarchanoff's experiments are reliable as regards the frog, Steinach points out that we may still ask whether in mammals the integrity of the seminal receptacles is bound up with the preservation of sexual excitability. This cannot be taken for granted, nor can we assume that the seminal receptacles of the frog are homologous with the seminal vesicles of mammals. In order to test the question, Steinach chose the white rat, as possessing large seminal vesicles and a very developed sexual impulse. He found that removal of the seminal sacs led to no decrease in the intensity of the sexual impulse; the sexual act was still repeated with the same frequency and the same vigor. But these receptacles, Steinach proceeded to argue, do not really contain semen, but a special secretion of their own; they are anatomically quite unlike the seminal receptacles of the frog; so that no doubt is thus thrown on Tarchanoff's observations. Steinach remarked, however, that one's faith is rather shaken by the fact that in the Esculenta, which in sexual life closely resembles Rana temporaria, there are no seminal receptacles. He therefore repeated Tarchanoff's experiments, and found that the seminal receptacles were empty before coitus, only becoming gradually filled during coitus; it could not, therefore, be argued that the sexual impulse started from the receptacles. He then extirpated the seminal receptacles, avoiding hemorrhage as far as possible, and found that, in the majority of cases so operated on, coitus still continued for from five to seven days, and in the minority for a longer time. He therefore concluded, with Goltz, that it is from the swollen testicles, not from the seminal receptacles, that the impulse first starts. Goltz himself pointed out that the fact that the removal of the testicles did not stop coitus by no means proves that it did not begin it, for, when the central nervous mechanism is once set in action, it can continue even when the exciting stimulus is removed. By extirpating the testicles some months before the sexual season he found that no coitus occurred. At the same time, even in these frogs, a certain degree of sexual inclination and a certain excitability of the embracing center still persisted, disappearing when the sexual epoch was over.

According to most recent writers, the seminal vesicles of mammals are receptacles for their own albuminous secretion, the function of which is unknown. Steinach could find no spermatozoa in these "seminal" sacs, and therefore he proposed to use Owen's name of glandulæ vesiculares. After extirpation of these vesicular glands in the white rat typical coitus occurred. But the capacity for procreation was diminished, and extirpation of both glandulæ vesiculares and glandulæ prostaticæ led to disappearance of the capacity for procreation. Steinach came to the conclusion that this is because the secretions of these glands impart increased vitality to the spermatozoa, and he points out that great fertility and high development of the accessory sexual glands go together.

Steinach found that, when sexually mature white rats were castrated, though at first they remained as potent as ever, their potency gradually declined; sexual excitement, however, and sexual inclination always persisted. He then proceeded to castrate rats before puberty and discovered the highly significant fact that in these also a quite considerable degree of sexual inclination appeared. They followed, sniffed, and licked the females like ordinary males; and that this was not a mere indication of curiosity was shown by the fact that they made attempts at coitus which only differed from those of normal males by the failure of erection and ejaculation, though, occasionally, there was imperfect erection. This lasted