1. Bilateral symmetrical reactions of vasomotoric origin, related to dermatoma, are observed in cases of reflex-erythema, cerebral disease (intoxication, brain tumor, injury of the brain-stem, encephalitis), in a great number of allergic skin reactions (drug rush, eczema, peliosis rheumatica, purpura, measles, scarlatina), in leukemia, liver cirrhosis, virus infections, etc.