STUDY OF THE ETIOLOGY OF AMYOTROPHIC LATERAL SCLEROSIS.

Although various hypotheses have been put out as to the etiology of amyotrophic lateral sclerosis, they do not seem to date to have been substantiated by experimental evidence. As the incidental outcome of studies on possible carcinogenic processes, the authors of this paper have obtained experimental data indicating the possibility of reproducing amyotrophic lateral sclerosis in monkeys by administering extracts from the spinal cord of persons who have died of the disease. The illness in monkeys is marked by a long incubation period, which may be of five years or more, and it is very similar to the disease in man in its clinical and pathological picture. The experimental evidence strongly suggests that this disease is of virus origin. The virus-like agent discovered has been passaged twice in monkeys without consequent attenuation; it is not pathogenic for mice and other laboratory animals.The authors point out that, before final conclusions can be drawn, serological and immunological confirmation is required. Research is now proceeding to that end.