Our knowledge of the pathology of anterior poliomyelitis dates from 1863, at which time Cornil1 published the report of an autopsy on a patient who died at the age of 49, forty-seven years after the acute attack. He noted the loss of nerve-cells and atrophy of the affected muscles. Two years later Prevost2 described an autopsy on a still older case in which he found loss of nerve-cells, overgrowth of neuroglia, and asymmetry of cord, with reduction in the size of the left ventral horn. Johnson and Clarke,3 in 1868, from a study of the spinal cord of a man aged 32, who had suffered his acute attack in early infancy, advanced the opinion that atrophy of the nerve-cells is the cause of changes in the voluntary muscles. A similar case led Charcot and Joffroy,4 in 1870, to state that the ventral nerve-cells are first and