Pains of abdominal irritation are, however, without doubt produced in some cases by unsuspected faults of diet, and may even recur in such a quasi-periodic manner as to strongly suggest the idea of neuralgia in the lumbo-abdominal nerve. One special variety of this happens, I believe, much more often than is thought. A patient will habitually take considerable quantities of some article of food which he does not readily digest, but which is not at all acutely irritant: under these circumstances a simple accumulation is apt to take place in the colon, especially at the top of the ascending colon, the top of the descending colon, or just above the sigmoid flexure, or else in the cæcum. The result of accumulation in the last of these places is not unfrequently typhlitis and perityphlitis, this part of the bowel having (for some reason) a special tendency to inflammation. Deposits in the other localities named are rarely the cause of inflammation, but they very frequently give rise to violent pain, which is exceedingly apt to be taken for the pain either of gall-stone, of renal calculus, or else of some abdominal neuralgia. In cases, therefore, where there is any possibility that accumulation is the cause of pain, it is highly desirable to commence with a dose of castor-oil and laudanum, followed up, if needful, by the administration of a large warm-water enema, given through an O'Beirne's tube. The most violent and recurrent attacks of pain in the renal region, the flank, the abdomen, or the groin, will sometimes be instantly cured by such means, sufficiently proving the non-neuralgic character of the complaint. I have elsewhere explained that the impaction of a renal or an hepatic calculus, in the ureter or the ductus choledochus, may set up a true neuralgia in persons with the requisite congenital predisposition. The passage of renal or hepatic calculi may give rise to symptoms falsely suggesting neuralgia, which require just to be mentioned here. But there is no need to dwell much upon the diagnosis, for the passage of renal or hepatic calculi has always attendant symptoms and features of constitutional history, which ought to preserve the physician from mistake. The sensation of constriction, of nausea and vomiting, the faintness approaching to collapse, the persistent and constantly increasing severity of the pain up to the moment at which mechanical relief occurs, to say nothing of other phenomena, are distinctive to the skilled observer, and, when taken in conjunction with the history of past attacks, if any, will always prevent mistakes. In the few cases which might still be doubtful it will be well to try the effect of a relaxing dose of chloroform, which, in the case of calculus, will often put an end to the paroxysm at once and finally. CHAPTER XI. DYSPEPTIC HEADACHE.