Page:Popular Science Monthly Volume 14.djvu/662

644 was produced by the application of a dressing to an anal fistula, which ceased when the dressing was removed, and again appeared on its reapplication. In this case the vessels of the kidney seem to have been reflexly affected by the irritation applied to the anal nerves to such an extent as to produce albuminuria, although probably no organic disease of the kidneys themselves was present. Exposure of the abdominal walls to rapid changes in temperature may bring on diarrhœa, as the natives of India well know. It is possible that in these instances the cold acts through the abdominal walls upon the intestines themselves; but it seems also highly probable that some part at least of the action is reflex from the surface of the abdomen. Whatever the cause of it may be, however, it may be guarded against by wearing a cummerbund, like the Hindoos; and it is well for persons who are subject to diarrhœa to wear, even in this country, a warm woolen or silken belt around the abdomen.

Irritation in the intestines may induce, not merely vomiting and diarrhœa, but even general convulsions; and cases are on record of epileptic fits having been produced by the presence of a tapeworm in the intestine, which ceased upon the expulsion of the intruder. Hysterical fits, although their pathology is far from being understood, are now becoming to some extent associated with ovarian irritation; for it is found that, in many cases of hysteria, the ovaries are tender upon pressure, and that the hysterical fit may frequently be instantaneously arrested by pressing upon the ovaries.

We have so far been dealing chiefly with reflex action as a cause of disease, but now we must say a word or two respecting the transference of impressions. It is well known that persons who have had their legs amputated often complain of cold feet, or of pains in their toes, on change of weather. The irritation here is really in the end of the divided nerve in the stump. But the brain is accustomed to refer all impressions made upon a nerve during its course to the terminal filaments from which impressions usually come, just as we feel a tingling in the fingers when we pull upon or jar the ulnar nerve, or, as it is popularly termed, the funny-bone. In disease of the hip, the irritation is felt, not so much in the hip itself, as in the knee.

In headaches one can frequently trace the origin of the pain to some point at a distance from the aching part. Some years ago I met with a case which was to me very instructive. A woman complained of a headache situated in the left temple. One of her teeth at the same time ached somewhat, and I gave her a pledget of cotton-wool, dipped in solid carbolic acid, to put into the cavity. To my disappointment it had little or no effect; but five minutes afterward, on the removal of the cotton-wool to the cavity of a second tooth, likewise decayed, but which had not at first been suspected as the cause of the mischief, the pain disappeared entirely from the temple. Some time afterward I was led to discover an unsuspected decayed spot in one of