Nonsuppurative encephalitis includes all inflammations of the brain not characterized by the formation of an abscess and therefore a number of unrelated diseases: polio-encephalitis, epidemic encephalitis, encephalitis secondary to a contiguous meningitis and a vague, indefinite condition called toxic encephalitis. The first three types have been carefully studied clinically; they reveal specific pathologic changes and are probably due to invasion of the brain substance by a specific virus even though it has not yet been demonstrated. Little is found in the literature to prove that toxic encephalitis is anything but a clinical designation. According to some textbooks, however, such an involvement of the brain is not uncommon. Dana,1for example, speaks of a secondary or toxic encephalitis and of an encephalitis due to influenza, by which he does not mean the epidemic type. In 1884, Strümpell2and later Leichtenstern described an encephalitis characterized, aside from the acute general