The presence of paralysis in the muscles and the association of nerve lesions to muscular paralysis led investigators to examine the nervous system, and probably more attention has been paid to the pathology of poisoning in this direction than in any other. Many records of isolated cases are to be found in the literature of the subject, and the examination of the spinal cord has been carried out in many instances; several have been cases of generalized paralysis or dementia, with involvement of the trunk muscles as well as those of the extremities in the paresis. Many observers who have made histological examinations in such cases have found nuclear changes in the anterior columns of the cord suggesting polymyelitis. A small number only of the total cases of paresis, however, come under this heading. Vulpian[25], Oppenheimer[26], Oeller[27], and others, described degenerative and proliferative changes in the grey matter of the cord. Steiglitz[28] by animal experiments produced inflammatory processes in the anterior grey substance, vacuolations in the ganglion cells, and degeneration in the anterior root ganglia. In the paralyzed muscles the changes of degeneration are found: the muscle nuclei become spindle-shaped, the interstitial tissue undergoes degeneration, the muscle becomes atrophied, takes the stain badly, shows irregular striation, and the muscle bundles become ill-defined and fused. Scarcely any two observers are agreed as to the exact nerve lesions which are to be found, and so at variance are the various theories based upon the pathological findings that it is by no means uncommon to find two sets of observers quoting the same electrical reactions and histological appearances as proving in the one case peripheral, and in the other the central, origin of the paralysis. On the other hand, in the quite early observations of Hitzig[29] particular attention was called to the bloodvessels and their possible association with the disease. Moreover, as has been already cited, ancient physicians were in the habit of making use of lead as a styptic and hæmostatic because of its peculiar action on the blood. Probably as a result of improved histological methods of examining the nervous tissue, renewed attention was given to the nerve fibres and nerve cells, with the result that, in the very large number of observations recorded, many different nerve lesions are described as the sequelæ of lead intoxication.