A circumstance which possibly justifies my intrusion into dermatologic circles is the fact that the allergic phenomena to be described can be observed more accurately in surface tissues, such as the skin, than they can in the deeper tissues which may be similarly involved. For this reason, an opportunity for accurate study in this line is offered more frequently to dermatologists than to specialists in other lines. It is well known that patients can become hypersensitive to a large variety of material substances and react whenever they come in contact with them. Some patients are so sensitive that they become ill on contact with minute traces of the agents to which they react. For example, those sensitive to eggs often react to the trace of egg contained in hen meat; those sensitive to buckwheat may be made ill by the trace of buckwheat in a drop of honey; infants sensitive