Clinical allergy has been recognized for thirty years. Before then asthma, hay fever, urticaria and eczema were considered somehow related, but the demonstration that all these were manifestations of a single underlying disorder, then called "protein sensitization" or "anaphylaxis," was an advance in medical progress. Not only was this type of human hypersensitiveness demonstrated by means of a positive reaction to a cutaneous test but this test presumably indicated the actual substance, such as a particular food, pollen or animal dander, that caused the symptoms of which the patient complained. This dramatic revelation soon took hold on medical imagination.
During the first fifteen years the cutaneous test was the keystone to the practice of allergy. Many hundreds of allergens were found to produce positive reactions, and there was continual search for new ones. Foods, plants, hair from native and wild animals and bacteria were extracted in increasing numbers until as