This skin eruption more than any other is due to dietetic faults or to idiosyncrasies. Certain foods provoke an urticaria in those who are liable to it, as certainly as iodids and bromids produce acne in others. It is not necessary for its production that the food be stale or spoiled. The cleanest or freshest fruit or shell-fish may cause it. Whether the eruption is due to an attempt to eliminate through the skin certain substances introduced into the blood from the offending food, or is provoked by irritation of the unduly sensitive vasonervous mechanism, is not certain. Overloading the stomach will also cause it in many cases. Those who are inclined to gout, frequently suffer from urticaria when they indulge in too much nitrogenous food.

Idiosyncrasy marks the causal relationship of foods to this disease. One article after another must be forbidden until the toxic one is found. Shell-fish, crustaceans, and strawberries are most likely to provoke attacks. Not infrequently a patient will be found who cannot eat buckwheat cakes without attacks of urticaria. Occasionally fish, pork, and eggs will excite it. To so great an extent is the relationship of food to the disease a peculiarity of each patient that no general diet can be prescribed.

One of the most persistent cases under my care occurred in a medical student. After repeatedly advising the discontinuance of first one article of food and then another, he told me that for economy he had been living on milk alone and had been drinking large quantities of it. As soon as the quantity of milk was diminished and his diet was varied more the urticaria disappeared.

In chronic cases it is difficult to discover the cause of the disorder. It must not be forgotten that uterine derangements will start outbreaks in some women.