The loss of erectile power is occasioned through more causes than one. Erection ensues independently of the will or imagination, as instanced on awaking in the morning—the cause is most probably a distended bladder; the phenomena may be a sympathetic irritability of the muscles of the perinœum, especially the erectores; there is a general pelvic disturbance, the nervous excitement is increased, and the rush of blood (obedient to that excitement) is sent to the penis: such, I believe, is the sympathy between all these structures. The will exercises the same, and the results of the imagination do not materially differ; consequently, where the mind fails in producing these effects, local excitants may be found to supply its office hence the usefulness of art in combating the eccentricities of nature. The mere handling of the testicles kindles desire, and in like manner, stimulatives applied over the scrotum generate amative heat. A curve of the penis is sometimes an obstruction to connubial intercourse; this arises from adhesion or obliteration of the cells of the _Corpora Cavernosa_ on one side only, preventing the uniform flow of blood into those structures, and consequently the equal distention of the penis. The curve is of course laterally, and occasions in the act of coition pain to both parties, or the power of penetration is insufficient. Occasionally this malformation is only temporary, and consequently remediable. _Franck_ gives an instance in which so considerable a portion of the penis had been carried away by a musket-shot, that when the wound healed, the organ remained curved, and yet proved adequate to the performance of its functions. An opinion formerly prevailed, that the existence of the testes was unnecessary for effective copulation; but that is no longer a point of dispute: their absence, whether natural or artificial, invariably rendering the invalid unfruitful. It is not, however, to be inferred, that a person is impotent in whom no testicles are discovered in the scrotum, instances occurring where they do not descend from the abdomen (their embryotic abode) through the whole period of life. One testicle, provided it be sound, is sufficient for procreation. Complete extirpation of the testes, although destructive of procreative powers, does not extinguish venereal desire. Where the genital organs exist, but are malformed, or pathologically altered, their virility may be nullified. The most frequent malformation is in the _urethra_, which sometimes opens in the perinœum—the part marked _a_ in the annexed cut; at others, on the dorsum of the penis, and not unfrequently under its surface: so long, however, as the orifice opens in that portion of the penis which enters the vagina, so that the _emissio seminis_ may be therein deposited, impregnation may and will take place; and even in cases where artificial means have been employed to convey the fluid. [Illustration]