There are special forms of lessened excitability, due to entirely natural causes, in which the sexual-center responds only to certain kinds of stimuli. These failures are chiefly psychic; as when a man with an abnormally small penis refuses to respond readily to a large woman, with a correspondingly large vulva; and, vice versa, the large woman fails equally to respond to the small man. A large, healthy man will not be apt to feel desire for a child; a virtuous man for a loose woman; nor the male libertine respond half so readily to his virtuous wife as to the more gross and libidinous solicitations of the prostitute. And these indices of sexual crime, though slight, should never be lost sight of by the jurist. They are instances of functional incapacity, however, resulting simply from cerebral inhibition; and do not belong rightfully to the class of neuroses which enter into the domain of forensic medicine. Commonly, they rather show normal clearness of mind as to cause and effect; and should be relegated to that category of minor sexual defects due either to irritable weakness of the erection-center, or reaction from excessive psychical excitement, as in those cases of spinal neurasthenia in which ejaculation takes place, ante portam; or the converse conditions of aspermia, and sexual anesthesia, in which the intensity of the pleasurable feeling depends on the degree of psychical excitement accompanying the act.