There are few subjects before the profession today more interesting and important than specific hypersensitiveness. The condition is common and afflicts perhaps 12 to 15 per cent. of adults.
Several sources of information are useful in the diagnosis of hypersensitiveness. From them, one can usually discover not only whether or not a given illness is fundamentally allergic in origin, but also what the specific allergen responsible for the illness may be. These sources of information are (1) family history; (2) personal history; (3) examination; (4) observation by the patient, and (5) specific tests (cutaneous, ophthalmic, nasal, subcutaneous, clinical, etc.)
Each source of information is important and, depending on the case, one may be more important than the others. For this reason, each will be discussed in some detail.
Specific hypersensitiveness is one of the most consistently hereditary of diseases. In outspoken cases, a positive history of the condition