Of great interest are the facts which have, in recent times especially, been scientifically established, pointing to a certain periodicity, to an undulatory movement of the general bodily functions of the female organism, dependent upon the sexual life. The observations of _Goodman_, _Jacobi_, _von Ott_, _Rabuteau_, _Reinl_ and _Schichareff_, have shown that in woman the principal vital processes pursue a cycle made up of stages of increased and diminished intensity, and that this periodicity of the chief general processes of vital activity finds expression also in the functions of the reproductive organs. _Goodman_ has compared this play of general vital functions to an undulatory movement. According to this writer, a woman’s life is passed in stages, each of which corresponds in duration with a single menstrual cycle. Each of these stages exhibits two distinct halves, in which the vital processes are respectively ebbing and flowing: in the latter we see an increase of all vital processes, a larger heat production, a rise in blood-pressure, and an increased excretion of urea; in the former we see, on the contrary, that all these vital processes display a diminished intensity. The moment when the period of increased vital activity is at an end, the moment when the ebb begins, corresponds, according to _Goodman_, to the commencement of the catamenial discharge. _Goodman_ sought for verification of this undulatory theory of the sexual life of woman in certain data regarding the bodily temperature and the blood-pressure. A more extensive research was undertaken by _Jacobi_, who, as the result of her observations, came to the following conclusions. In eight cases she noticed in the premenstrual epoch a rise of temperature ranging from 0.05° C. to 0.44° C. (0.09° F.–0.79° F.); and during the catamenial discharge a gradual fall of 0.039° C.–0.25° C. (0.072° F.–0.45° F.), never less, that is to say, than a quarter of a degree Centigrade; but in the majority of cases the temperature did not, while the catamenia lasted, regain the normal mean. She further observed in the generality of cases an increased excretion of urea during the premenstrual epoch; and a notable fall in blood-pressure during menstruation. _Reinl’s_ observations on healthy women, in whom menstruation ran a normal course, showed that in the great majority of cases in the premenstrual epoch the temperature was elevated as compared with that of the interval, that in eleven out of twelve cases the temperature gradually declined during menstruation, to fall in three-fourths of the cases below the mean temperature of the entire interval, and exhibiting in the post-menstrual epoch a still further depression, giving place, however, to a somewhat higher mean temperature during the first half of the interval. In the second half of the interval a higher mean temperature was observed than in the first half.