THE ACUTE disseminated encephalomyelitis that sometimes follows vaccination against rabies1 or smallpox,2 as well as the postinfectious encephalomyelitis following exanthematous diseases, bears such an apparently close relation to multiple sclerosis, Schilder's disease (progressive subcortical encephalopathy) and other demyelinating processes in the central nervous system that it has attracted the attention of numerous investigators in recent years. But it was in 1895 that Pierre Marie3 first stressed the observation that multiple sclerosis frequently followed smallpox. The literature has been rather completely covered by Ferraro4 and the reader is referred to him for a bibliography dealing with phases of the problem that are beyond the scope of the present experiments.
As long ago as 1898, while studying the toxic effects of tissues of other species, during his investigations on diphtheria and on rabies, Centanni5 observed the untoward effects of saline suspensions of brain injected into rabbits. He