Like other nervous disorders, involuntary seminal emissions sometimes manifest themselves in several members of the same family through several generations, being the result of inherited predisposition. In this class of cases the subjects are of a nervous, excitable, or irritable temperament, somewhat anæmic, and possibly suffered during infancy from nocturnal enuresis. Among the predisposing causes the most common is indulgence in erotic fancies, which terminates in increased reflex impressibility of the centres which preside over the genital organs. The affection is, however, usually acquired, being met with particularly in single subjects toward the termination of the second decade and between the second and third decades. Of these cases, at least nine-tenths can be traced to masturbation, while the remainder will be found to have had gonorrhoea or to have masturbated, suffered from gonorrhoea, or indulged their sexual propensities in various ways. Seminal incontinence is not common as the result of sexual coition, and it is highly probable that when married men are affected the sexual excess is engrafted upon a previously vicious habit. From a practical point of view, it is of the first importance to be aware of the fact that one or more strictures of the urethra will be found in 80 per cent. of all cases, and that decided hyperæsthesia of the prostatic portion of the urethra is present in 94 per cent. of all instances. The rational explanation of morbid seminal emissions seems to be as follows: Under the influence of erotic ideas, masturbation, sexual excesses, or unsatisfied sexual excitement produced by dallying with women, exaggerated irritability of the genital organs is induced, and is {141} followed by subacute or chronic inflammation and abnormal sensibility of the urethra, particularly of its prostatic division, which terminate, in cases characterized by diurnal pollutions and spermorrhagia, in relaxation and dilatation of the orifices of the ejaculatory ducts. As the natural result of the constant excitability of the terminal filaments of the nerves distributed to the prostatic urethra, these nerves are alive to the slightest impressions, act as peripheral sources of irritation, and induce permanent increased mobility or irritability of the cerebral and spinal genital centres, through which the motor nerves of the ejaculatory apparatus are thrown into action, and an emission ensues. Seminal incontinence is an occasional accompaniment of injuries of the spine, and it is also met with during the progress of or convalescence from acute and chronic diseases which are marked by disturbances or exhaustion of the central nervous system. Thus, it may be symptomatic of phthisis, variola, typhus, progressive muscular atrophy, and incipient bulbar paralysis, ataxia, and paraplegia; while the habitual use of opium and chronic alcoholism predispose to its occurrence.