Drives: Part II
The internal organs are connected with the ganglia of the sympathetic branch of the autonomic nervous system; while the external genitals are connected with the sacral division of the same system. Periods of “heat” occur in female animals, and a distinct cycle of erotic excitement in women, closely connected with the menstrual cycle. The menstrual flow apparently furnishes a certain amount of mechanical, and possibly also chemical, stimulation to the clitoris, the female external genital organ, with its associated viscera sacrally innervated. Reflex excitations connected with erotic drive show a high degree of alliance, one with the other, the change in self pattern being rather a question of change in balance, with all usual activities retained. The behaviour of adolescent girls, during and following menstruation periods, shows certain characteristics apparently attributable to changes in self activity brought about by the menstrual phenomena.