DERMATOLOGY

is extension of the disease, in accordance with the nature of the yet undiscovered cause. It is sometimes true that an artificial dermatitis, induced by the application of an external irritant, does disappear when this is no longer efficient, yet frequently it leaves behind an eczema, ^vhich may last weeks or months. It is customary to assume a predisposition to eczema, which is little more than a confession of ignorance. It is not disputed that there are contributory elements in individual constitutions, but such play a subordinate part. Dermatitis due to Pediculi affecting the scalp does not cease with the destruction of the