Trichophytin may be defined as an extract of fungi which is used both for diagnosis and for treatment. It has been firmly established by many investigators since the original preparation of trichophytin in 1902 by Plato and Neisser that the positive reaction following intracutaneous administration of this substance is due to a specific sensitivity resulting from a fungus, i. e., a Trichophyton infection.
A long list of investigators1 (Sulzberger, Lewis, Wise, Van Dyck, Kingsbury, Throne, Meyers, Pennington, Robinson, Grauer, Traub, Tolmach, Peck and many others) have demonstrated that repeated injections of trichophytin have with fair regularity succeeded in reducing the specific sensitivity of the skin to trichophytin, which may be interpreted as desensitization. However, therapeutic success both as far as the primary infection is concerned and in regard to influencing eruptions which can be properly considered ids has not paralleled the production of the hyposensitivity.
Fungi of the Epidermophyton,