The spermatozoa being absent, the sperma is much thinner than in the normal state. The absence of the spermatozoa and their movements is also the cause why the Boettcher’s crystals usually form much earlier; they appear within half an hour after ejaculation and in a considerable amount. They often cover almost the entire microscopical field. In the normal semen the movement of the spermatozoa prevents the early formation of the crystals; they appear after several hours’ standing and are fewer in number. The thin azoospermatic semen is more transparent and watery and contains more epithelia and fat than normal semen. The patient is, as a rule, unaware of his anomaly. It is often discovered after his wife has undergone innumerable treatments for her supposed sterility. If the anomaly has been caused by gonorrhoea with the accompanying inflammation of the testicles, epididymitis, or spermatic funiculitis, the loss is almost irremediable. The revelation to the couple of their doom to childlessness is one of the many tragedies played in the doctor’s office. _Impotence of copulation._—The anomaly, most complained of, which drives the patient to seek medical help is the impotence of copulation. It is the anomaly which strikes the hardest blow to masculine vanity. It is a psychological fact that most men are proud of their potency of copulation and feel greatly humiliated when the same is impeded. A woman will not seldom discuss with her friends the double ovariotomy performed upon her, but the man deprived of his testicles will never mention the fact of his castration to his closest friends. The impotence of copulation is best divided into four types: 1) Organic impotence. 2) Symptomatic, or paralytic impotence. 3) Psychic, a) transitory, b) relative, c) temporary impotence. 4) Atonic impotence. _Organic impotence_ may be congenital or acquired. Among the congenital forms are total absence of the penis. Smallness of the penis may also be the cause of impotence, although this cause has been somewhat exaggerated by most writers. The male generative organs on the Greek statues are in comparison with the size of the other parts quite small. Still, if the smallness goes beyond a certain degree it will cause impotence. In the same way enlargement of the penis beyond a certain degree will also result in impotence. Adhesions of the penis to the neighboring parts or torsion of the penis will render intromission impossible. Congenital absence of the testicles is always accompanied by loss of power. Among the acquired deformities are counted neoplasms of the penis, elephantiasis, and the destruction of the penis through ulceration. Syphilis and tuberculosis of the testicles are generally destructive to virility. Removal of the testicles, even if operated later in life, is, after a certain time, followed by atrophy of the penis and impotence. Indurations and ossifications of the cavernous bodies lead, as a rule, to impotence.