Amenorrhœa at the time of the menarche may depend on complete aplasia of the ovaries, associated with a rudimentary and imperfect development of the uterus. In such girls, the development of whose reproductive system is thus imperfect, the continually expected menstrual flow fails to appear, in spite of the fact that a recurrent menstrual discomfort, evoked by the congestion of the genital organs, recurs at intervals of four weeks; as, for instance, colicky pains in the abdomen, irritable, nervous states, and mental disturbances. Further, amenorrhœa may be due to one of the various forms of atresia of the genital organs, as for instance to vaginal or hymeneal atresia. In such individuals the first period passes by without anything to attract attention. But at the second period, distress will usually be manifested; and from this time forward, painful contractions of the uterus will continue to occur at four-weekly intervals, and to become more violent as period succeeds period, whilst the menstrual discharge is wanting, or, to speak strictly, fails to find an outlet. The blood collects behind the seat of atresia, and the accumulation gives rise to pressure symptoms affecting the bladder and the rectum, and ultimately also the sacral nerves. Menstruation, after its first appearance in normal fashion, may be suppressed in young girls in consequence of mental impressions, such as sudden fright; such cases are observed after an escape from a fire, or after a railway accident. Mental stimuli of less intensity but longer duration have a similar effect; sometimes these take the form of auto-suggestion. A well-known instance of the latter phenomenon is furnished by the case of a girl who, in consequence either of actual intercourse or it may be merely of too intimate an embrace with a man, fears she has become pregnant, and actually suffers from amenorrhœa though pregnancy does not really exist. I saw a case in which amenorrhœa was thus produced in a girl seventeen years of age, whose ideas on the process of sexual intercourse were still far from clear. She had permitted a young man to kiss her repeatedly and fervently, and to clasp her in a close embrace. She was then afraid that she had become pregnant; the catamenial flow, which had been regular since she was fifteen years old, ceased to appear; and it was not until at length I was consulted, was able to assure myself that the girl was essentially virgin, and was, therefore, in a position to reassure her as to her own condition, that menstruation again became regular.