it is as an incident arising during tumescence and influencing its course that we must probably regard nearly every sexual aberration.  It is with the second stage of the sexual process, when the instinct of detumescence arises, that the analogy of evacuation can alone be called in.  Even here, that analogy, though real, is not complete, the nervous element involved in detumescence being out of all proportion to the extent of the evacuation.  The typical act of evacuation, however, is a nervous process, and when we bear this in mind we may see whatever truth the evacuation theory possesses.  Beaunis classes the sexual impulse with the “needs of activity,” but under this head he coordinates it with the “need of urination.”  That is to say, that both alike are nervous explosions.  Micturition, like detumescence, is a convulsive act, and, like detumescence also, it is certainly connected with cerebral processes; thus in epilepsy the passage of urine which may occur (as in a girl described by Gowers with minor attacks during which it was emitted consciously, but involuntarily) is really a part of the process.[48]

There appears, indeed, to be a special and intimate connection between the explosion of sexual detumescence and the explosive energy of the bladder; so that they may reinforce each other and to a limited extent act vicariously in relieving each other’s tension.  It is noteworthy that nocturnal and diurnal incontinence of urine, as well as “stammering” of the bladder, are all specially liable to begin or to cease at puberty.  In men and even infants, distention of the bladder favors tumescence by producing venous congestion, though at the same time it acts as a physical hindrance to sexual detumescence[49]; in women—­probably not from pressure alone, but from reflex nervous action—­a full bladder increases both sexual excitement and pleasure, and I have been informed by several women that they have independently discovered this fact for themselves and acted in accordance with it.  Conversely, sexual excitement increases the explosive force of the bladder, the desire to urinate is aroused, and in women the sexual orgasm, when very acute and occurring with a full bladder, is occasionally accompanied, alike in savage and civilized life, by an involuntary and sometimes full and forcible expulsion of urine.[50] The desire to urinate may possibly be, as has been said, the normal accompaniment of sexual excitement in women (just as it is said to be in mares; so that the Arabs judge that the mare is ready for the stallion when she urinates immediately on hearing him neigh).  The association may even form the basis of sexual obsessions.[51] I have elsewhere shown that, of all the influences which increase the expulsive force of the bladder, sexual excitement is the most powerful.[52] It may also have a reverse influence and inhibit contraction of the bladder, sometimes in association with shyness, but also independently of shyness.  There is also