(d) _Irritable weakness._ In this condition there is abnormal impressionability of the centre, but accompanied by rapid diminution of its energy. There may be functional disturbance of the centre itself, or weakness of the innervation through the nervi erigentes; or there may be weakness of the ischio-cavernosus muscle. Cases in which the erection is ineffectual, on account of abnormally early ejaculation, form a transition to the following anomalies:— _2. Affections of the Ejaculation Centre._ (a) _Abnormally easy ejaculation_ from absence of cerebral inhibition, resulting from excessive psychical excitement or irritable weakness of the centre. In this case, under certain circumstances, the simple conception of a lascivious situation is sufficient to set the centre in action (high degree of spinal neurasthenia, usually resulting from sexual abuse). A third possibility is hyperæsthesia of the urethra, by virtue of which, when the semen enters it, an immediate and excessive reflex action of the ejaculation centre is induced. In such a case, simple proximity to the female genitals may be sufficient to induce ejaculation (_ante portam_). In case of hyperæsthesia of the urethra as a cause, the ejaculation may be accompanied by painful, instead of pleasurable, sensations. Usually, in cases where there is hyperæsthesia of the urethra, there is, at the same time, irritable weakness of the centre. Both functional disturbances are important in the production of pollutio nimia and diurna. The accompanying pleasurable feeling may be pathologically absent. This occurs in defective men and women (anæsthesia, aspermia?), and, further, as a result of disease (neurasthenia, hysteria); or (in prostitutes) it follows overstimulation and the blunting thus induced. The intensity of the pleasurable feeling depends on the degree of psychical and motor excitement accompanying the sexual act. Under pathological conditions this may become so pronounced that the movements of coitus take on the character of involuntary convulsive movements, and even pass into general convulsions. (b) _Abnormally difficult ejaculation._ It is occasioned by inexcitability of the centre (absence of libido, paralysis of the centre: organic, from disease of brain or spinal cord; functional, from sexual abuses, marasmus, diabetes, morphinism), and, in this case, for the most part, in connection with anæsthesia of the genitals and paralysis of the erection centre. Or it is the result of a lesion of the reflex arc, or of peripheral anæsthesia (urethra), or of aspermia. The ejaculation occurs not at all, or tardily, in the course of the sexual act, or only afterward, in the form of a pollution. III. CEREBRAL NEUROSES. 1. _Paradoxia_, _i.e._, sexual excitement occurring independently of the period of the physiological processes in the generative organs.