The cases of this nature that have come under my observation have not been in girls of the working classes, but among the well-to-do. We cannot therefore regard them as due to overstrain of the heart in consequence of excessive bodily exertions, comparable to the cases met with in young recruits after long marches and violent exercise. We must rather assume that the development of the female genital organs has evoked a storm in the cardio-vascular system, more especially that in some way an increased resistance has been offered to the work of the heart, and that thus the hypertrophy has been brought about; though we may suppose that other unfavorable influences have also been in operation. Such an influence, in these cases, is the rapid growth of the body, which makes enhanced demands on the work of the heart; another is furnished by the almost universally worn unhygienic article of clothing, the cuirass-like corset, which offers a rigid hindrance to the rapid growth of the female body, to the development of the breasts, the thorax, and the upper abdominal organs, and which fails to accommodate itself to the changing conditions of growth, so that much extra work is thrown upon the heart. In such young girls we have very frequently found tight stays, which were worn unchanged without regard to the growth of the body in length, and which, by pressure on the epigastric region, elevation of the diaphragm, and limitation of the respiratory movements of the thorax, actually offered such considerable resistances to the driving power of the heart, as ultimately to lead to hypertrophy of the cardiac muscle. Summing up our observations, we find that at the time of the menarche cardiac disorders occur in young girls which may be arranged in three groups of cases: 1. Nervous palpitation and paroxysmal tachycardia in persons in other respects in good health, the affection appearing shortly before the commencement of menstruation, and disappearing soon after the flow is regularly established. 2. Cardiac disorders occurring in young girls suffering from chlorosis, which itself results from the processes of the menarche. 3. Cardiac hypertrophy developing at the time of the menarche, and dependent on the circulatory disturbances associated with that process, its appearance being favored also by rapid growth of the girl and by unsuitable clothing (tight lacing).