If the adolescent young man is leading a continent life, we may assume that from time to time he is subjected to conditions which serve as strong sexual stimuli, arousing in him a definite desire for sexual intercourse; but leading a continent life, he curbs his desire and fixes his thoughts upon other subjects. In this way, though the sexual excitement is brought quickly under abeyance, we can rest assured that a certain number of spermatozoa have been released from the testes; and that the other secretions have been increased in volume. The excitement may be sufficient even to cause an erection, and produce a few drops of the secretion of Cowper's glands. The spermatozoa, together with a small amount of the liquid secretion, will make their way gradually along the vasa deferentia and collect in the ampullæ. The bulk of the liquid secretion, however, will, in the course of the following hours or days, be reabsorbed, thus making for virility. The small advance guard of spermatozoa that may have made their way to the ampullæ will undergo a gradual decrease of their nascent activity, as the days go by. On the occasion of the next nocturnal emission the ampullæ will empty along with the seminal vesicles and these spermatozoa pass out. If they be examined under the microscope as a part of a normal nocturnal emission, they will be found to be almost motionless or very greatly lacking in typical spermatozoon activity. Now let us suppose that the young man, instead of curbing his sexual appetite, resorts, after a season of erotic imaginations, to the act of masturbation. We may picture the seminal ducts, vasa deferentia and ampullæ as being gorged with the secretion of the testes, including, of course, myriads of just released and nascent spermatozoa, together with several cubic centimeters of the liquid portion of the testicular secretion. The act of masturbation causes an orgasm and leads to a complete emptying of all these ducts. Thus we note that in this case the virile fluid is wasted, not being used in the procreative act or reabsorbed to exert its influence on virility. Nature's ends have been defeated. The system suffers a certain degree of depletion from which it recovers only after hours or even days. It must be evident from this picture of the processes that go on in the male sexual apparatus incident to the act of masturbation that the act cannot be performed repeatedly, as it naturally is when it becomes a habit, without interfering with the virility of the adolescent male. In the study of a large number of cases the author has found that the principal _physical_ changes that occur in a young man as the result of this habit are, flabbiness of muscle and clamminess of hands. The really virile man possesses firm muscles and clear, direct eyes and a strong grip; usually also a warm grip.