It is far otherwise with the genito-urinary apparatus; in a large number of cases, irritations proceeding from these organs do undoubtedly contribute to the production of neuralgia, though by no means in the important degree which many authors seem to have assumed. There can be no doubt, for example, that the irritation of a calculus, either within the kidney itself, in the ureter, or in the bladder, may set up violent neuralgia, which for the most part is localized in the branches of the lumbo-abdominal nerves. The instance of the eloquent Robert Hall is an example of renal calculus acting in this way: he suffered the most excruciating agony for years, and was obliged to take enormous quantities of opium in order to make life endurable. An instance of calculus impacted in the ureter, in a gentleman somewhat past middle age, occurred in my own practice; the lumbo-abdominal neuralgia occurred in frequent paroxysms of dreadful severity; and another case, already referred to was that of a woman, in whom ovarian neuralgia was undoubtedly in great part due to the irritation of an impacted calculus in the ureter. These cases, however, are very rare in comparison with others in which the peripheral source of the neuralgia is either the uterus or ovary, or the external genitals. I have no means of ascertaining, with anything like accuracy, the frequency with which the internal sexual organs are the starting-point of neuralgia, because the majority of such cases pass, naturally, to the care of physicians who practice chiefly in the diseases of women, and consequently not adequately represented either in my hospital or my private practice; still, I have seen a good many of these affections, and, though I speak with the reserve necessitated by the circumstances just named, I am much inclined to believe that even such powerful centripetal influences as those of the states of commencing puberty, of pregnancy, of the change of life, and uterine diseases generally, are very rarely the cause of true unilateral neuralgia, except in subjects with congenital tendencies to neuralgia. But in predisposed subjects there can be no doubt that these influences assist most powerfully in producing the malady.