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The clinical significance of a cutaneous test depends on a number of factors, namely: (1) clinical specificity; (2) the employment of a specific irritant, and (3) the production of a specific pathology. Irritants are responsible for histologic changes in tissues and these, in turn, call forth the invasion of certain cellular elements in the tissues affected. In the main, the type of the invading cell determines the general character of the lesion, i. e., polymorphonuclear cells characterize an acute inflammatory process; lymphocytes, mononuclears and endothelial cells, a subacute inflammatory process; and fibroblasts, a chronic process. The phenomena of degeneration, necrosis, etc., are, in the main, associated pathologic occurrences. It is, however, the multiplicity of these various pathologic phenomena and their peculiar localization, together with the presence of definite secondary pathologic changes, that give to a histologic picture a specific character.
While this paper concerns itself primarily with a histologic study