(1) The application of the Nissl method to the study of the motor cells of the spinal cord, and the nerve cells of the dorsal root ganglia in typhoid fever, shows that these cells regularly suffer pathological changes in the course of the infection.
(2) The alterations in the motor cells are more constant and of a severer grade than are those in the cells of the sensory ganglia. The more characteristic changes consist of disintegration, solution and destruction of the chromatic substance of the cell starting from the axone hillock and proceeding toward the nucleus. Coincidently the nuclei of the affected cells seek the periphery. Alterations are also suffered by the nucleus and nucleolus.
(3) While this central form of ehromatolysis is the prevailing type of pathological change, disintegration, etc., of the Nissl bodies situated in the periphery of the cell and in the dendrites is also observed (peripheral chromatolysis).
(4) In experimental infection with typhoid bacilli in rabbits a similar series of lesions in the corresponding nerve cells in the spinal cord and ganglia is encountered.
(5) The main or central type of lesions discovered is identical with that found in man and animals after section, destruction, or even slight injury of the peripheral nerves.
(6) The examination of the peripheral nerves arising from the lumbar segment of the cord (the site in man and rabbit of the most profound changes) in rabbits inoculated with typhoid bacilli showed well-marked evidences of parenchymatous degeneration.
(7> It is probable that lesions of the peripheral nerves in typhoid fever in human beings are common and that the post-typhoid hyper sthesias and paralyses are due to this cause.
(8) Restitution of the chromatic granules may take place in the affected nerve cells, the new formation beginning about the nucleus and extending through the protoplasm.