Mott, shows that this increase is due to degenerative processes of the nervous system which may be due to a variety of causes.[179] In no other psychosis do we find such clear-cut pathological findings at autopsy as are readily demonstrable in general paresis. We are very largely indebted to the exhaustive researches of Nissl and Alzheimer, (1904)[180] for our information on this subject. Macroscopically adhesions of the dura to the calvarium and of the pia to the cortical substance are quite common. Opacities of the meninges are practically always present. Pachymeningitis hemorrhagica, externa or interna, is common, often with the formation of extensive hemorrhagic membranes. Ependymitis may be readily observed in the floor of the fourth and lateral ventricles. There is usually a reduction in the general brain weight, with atrophy of various parts, usually one side or the other of the cerebrum. The sulci are widened and the frontal lobes are often noticeably smaller in size. Less frequently the temporal, parietal or occipital regions are affected. Often there are localized foci of atrophy with cyst formation. The ventricles are frequently widely dilated, with an increase of cerebrospinal fluid. Microscopic examination always shows a more or less diffuse leptomeningitis with a markedly thickened pia infiltrated with lymphocytes and plasma cells. In the superficial layers of the cortex there is a neuroglia proliferation with characteristic "spider cells." There is an obvious disturbance of the normal layering of the cortex which is very striking. The adventitia of the vascular walls shows an extensive infiltration by lymphocytes and particularly by plasma cells which are often very numerous. Rod cells or "stäbchenzellen" as described by Alzheimer are very noticeable as are also satellite cells or free nuclei. The neurones are often diminished in number and frequently show the "acute" or "grave" alterations described by Nissl, as well as shrinkage, sclerosis, pigmentary deposits, vacuolization, etc. The characteristic axonal alteration originally described by Turner as occurring in central neuritis is sometimes observed. Degeneration of the nerve fibres may be brought out by proper staining processes. Intimal thickening of the vessel walls and a capillary proliferation or budding should also be mentioned. Foci of softening sometimes are to be found in the cortex. The presence of occasional gummata is now conceded, although formerly denied by Alzheimer. The changes in the cerebellum are not essentially different, but are usually not so conspicuous. In the cord a pachymeningitis and leptomeningitis are usually present, as well as the vascular changes described above. The important findings, however, are the degeneration of the posterior columns and lateral tracts, or mixed forms involving both of these. Owing doubtless to defects in staining technique, the demonstration of the treponema is difficult and unsatisfactory. It