The pioneer observations of Noon (1) and Freeman (2) in England, of Clowes (3), Koessler (4), and Cooke (5), in this country, and the subsequent confirmatory experiences of many others with the specific treatment of atopic conditions (hay fever and bronchial asthma) leave no doubt of a certain effectiveness of the method. This method consists in the subcutaneous injection, at intervals of several days, of gradually increasing quantities of the exciting agent. The method referred to was conceived upon the basis of the procedure of desensitization in anaphylactic hypersensitiveness. However, there are at hand some observations by R. A. Cooke, which make it at least doubtful that the alleviating effect of the specific treatment of atopic hypersensitiveness is due to a desensitization, in the proper sense of that term. Cooke has found that, in individuals who have obtained complete relief from hay fever, as a result of injections of pollen extract, the degree of sensitiveness of the skin and even of the conjunctiva to the extract is the same as it was before the injections were begun.