On the other hand, the hyperthyroid type of woman reacts with an exaggeration of her tendency. When the posterior pituitary begins to secrete more in her its stimulation of the thyroid is enough to tip it over the normal line. Such a woman in the premenstrual phase becomes irritable and restless, does not know what to do with herself, cannot concentrate on conversation, occupation or any single activity, may become excited to the point of mania. Hot, tremulous, sleepless, or sleeping badly, she has a much harder time of it than her pituitary sister. These samples of premenstrual internal secretion reaction are the extremes of a vast number and variety of types. There are women in an unstable quasi-premenstrual state for the greater part of their lives. Sometimes an infectious disease or a psychic blow will put a woman into this class. The significance of these cyclic changes has been tremendously increased by the recent formal admission of women to participation in public activities on a plane of equality with men. Evidence exists that in man, too, there is some cyclic rhythmicity of his endocrines, which sets up a fluctuation in his physical and mental efficiency. The curves of these variations have still to be plotted, and will doubtless contribute no little to our knowledge of the control of human nature. One unexpurgated fact stands out: the reproductive mechanism of woman has rendered her whole internal secretion system, and so her nervous system, all her organs, her mind, definitely and sharply more tidal in their currents, more zigzag in their phases, more angular in their ups and downs of function, and so less predictable, reliable and dependable. THE MASCULINOID WOMAN