Abstract
In 1879 Galateir and Pasteur proved experimentally that rabies is an infectious disease, but it was not until 1903, when Negri described certain bodies in large nerve cells from the central nervous system, that anything was found which seemed absolutely specific for the disease. Negri regarded these bodies as protozoa, and their definite characteristic morphology, evidences of cyclic development, budding, and staining qualities indicate a protozoan structure resembling members of the Rhizopoda. They have also been so regarded by Anna Williams. The recent work of Covell and Danks, who employed newer methods of physics and chemistry, seems to refute this view. They state that the evidence is not compatible with the protozoan or organismal theories concerning the nature of the Negri bodies. The contention that these bodies arise from constituents already present in the nerve cell as a result of the action of the virus is in agreement with their findings; but they consider the evidence for the participation of the mitochondria, neurofibrils, and the nucleoli as inconclusive. Both the Negri bodies and the smaller typical lyssa bodies are probably formed by alterations in the basophilic Nissl substance, the fundamental ground substance of the cell, and by the addition of variable amounts of basophilic material of nuclear origin. There is no evidence that organisms on the borderline of microscopic visibility are cloaked with these cellular components in accordance with the chlamydozoal hypoth-
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