Among different diseases of the brain which are characterized by demyelinization of the white matter and which are mostly designated diffuse sclerosis, is one shown in a small group of four observations in which islands of preserved myelin have been reported. This type of demyelinization was described for the first time by Merzbacher1 in a child in whose family a peculiar hereditary disease of the brain had occurred in several generations. A second case from the same family was published by Spielmeyer and Liebers2 and, further, there are two sporadic observations, one by Bielschowsky and Henneberg3 and one by Bodechtel.4
This condition is patho-anatomically characterized by a peculiar degeneration of the white matter of both hemispheres of the brain and that of the cerebellum, the pons, the medulla and even the spinal cord. Within the destroyed areas there remain numerous perivascular myelin islands, so that the