“My comprehension of this subject compels me to endorse the parasitic theory, though it may excite your disapproval, and perhaps your ridicule, yet it can be easily verified by directing your management towards the destruction of the parasite, when all symptoms will disappear. Mercury is quoted as nearly a specific for the annihilation of these marauders, and the very best method of administration is by using Lotio Niger. “Thrice daily the patient should relax, the respiration of the cutaneous surface by the free application of hot water, just as hot as it can be comfortably endured. Then immediately afterwards _while the skin is made absorbent_ by the action of the liquid heat, it should be saturated with this medicine in the most thorough manner. Within three days time the itching will be reduced fifty per cent., but the complete result is attained only after a continued use of from four to eight weeks. “In many cases there will remain points or patches where the agent does not seem to act, and to these I usually apply the regular unguentum hydrargyri. Avoid all soaps and ointments except as above stated, thereby preventing the obstruction to absorption of the remedy as it has to enter the pores of the skin in order to act upon these energetic enemies that hold their victims under such a terrible bondage.” It is characteristic of pruritis for the paroxysms of itching to come on mostly after the patient gets warm in bed, at which time the annoyance may be further increased by a moisture or exudation about the anus. In longstanding cases the skin becomes thickened, horny in texture, and loses its pigment and elasticity. Sometimes portions of the radiating folds will become so hypertrophied and elongated, from the effects of gouging and scratching, that they look like and are sometimes called external piles, which in reality are nothing of the sort, but properly speaking would come within the range and meaning of non-syphilitic condylomata. I have successfully removed these formations by the same process adopted for the cure of piles. They go through similar changes after injection and open up a cavity surrounded by a ragged, thick, calloused skin, which, after first being cocainized, can be trimmed off with a pair of scissors. If there are several large tabs I do not operate on all at one sitting. [Illustration: FIG. 29.—Thickened condition of the skin in pruritis (Esmarch).] In the treatment of pruritis ani, a thorough search for a local cause and its removal will find a lasting reward in the results obtained. Of the obscure local causes, perhaps animal and vegetable parasites are the most difficult to find. The injection of a decoction of quassia bark or lime water and carbolic acid, will be efficacious in dislodging the oxyuris vermicularis, which may or may not be seen, like small pieces of white thread lodged between the anal folds.