In general paralysis, as in other mental diseases, the nervous discharge is accompanied by a greater disturbance in the structure of the gray substance of the brain, a more extensive decompounding of it, and consequently by a more complete exhaustion of nervous force than in healthy mental processes. Longer periods of rest and improved nutrition are therefore necessary to restore healthy function. In general paralysis, as in all other mental diseases dependent upon destructive disease of the brain, there is not only decompounding, but decomposing and disintegrating, of the structure of the brain. Posterior spinal sclerosis is frequently found. If alone or predominating over sclerosis of the lateral columns of the cord, the knee-jerk is abolished if the morbid process has gone far enough. If descending degeneration of the lateral columns is chiefly found, and is sufficiently advanced, the knee-jerk is increased. At least one of these forms of sclerosis exists in the vast majority of cases. There is also a distinctly syphilitic disease of the smaller cerebral arteries, together with a diffuse parenchymatous and interstitial encephalitis of syphilitic origin. At present we have no means of differentiating it at the autopsy from general paralysis following a subacute or chronic course, except inferentially from the presence of other evidences of syphilis. It is not always possible, therefore, to distinguish between syphilis and a syphilitic diathesis as the chief factor in diffuse encephalitis. DIAGNOSIS.—Although a well-marked case of general paralysis is unmistakable, the diagnosis in the early stages or in obscure cases may be extremely difficult. The varying degrees in which the various portions of the cortex, medullary portion, and different ganglia of the brain may be involved in the morbid process naturally give rise to a great variety in the symptoms, mental and physical, sensory and motor, emotional and intellectual, and in the relative preponderance of one or another in individual cases. The usual symptoms of any form of mental disease may for a time obscure the dementia which sooner or later must appear in general paralysis, and which, as has already been said, is the only mental symptom universally present in all cases. This mental impairment must also be associated with progressive muscular loss of power, although the relation of the two symptoms to each other, the degree to which a given amount of the one leads to a fair inference of a certain amount of the other, is liable to the greatest variation, the range of which can only be learned by observation and experience. There is a certain quality to the dementia, as already described, which is often sufficient of itself to establish the diagnosis with a practised physician.