In hardening of this organ, its density may be increased to that of boiled white of egg, or it may approach in consistence to that of a brain that has been hardened in alcohol, losing much of the sticky, adhesive character when broken up by the fingers, which marks the brain substance when in its normal state. The cause of the change is not well known, yet it is conjectured to be one of the results of inflammation, inasmuch as it is generally found with its capillaries greatly loaded with blood, while more or less fluid is found beneath the arachnoid and in the ventricles. The induration may affect the greater part or even the whole of the cerebral mass, or may be confined to particular portions or regions. In a case recently examined for Dr. Toothaker, of this city, where insanity of some years’ duration, and finally death, had followed a severe injury of the head, the brain was found so hard as to permit of fracture in the direction of the fibres, thus readily tracing their course. The symptoms that have most frequently been observed to accompany this change are, defect and gradual loss of memory, apathetic indifference, slight difficulty of articulation, followed by loss of sexual desire, partial palsy, fatuity, wasting and death. Extreme induration is often found in the brains of idiots. The whole organ may be found resembling in color and density boiled white of egg, or even cheese. The cerebral substance is shrunken, dense, and apparently quite void of vessels. =Hypertrophy= of the brain, is a condition in which there is usually increased hardness as well as increased volume, and is distinguished by flattening of the convolutions, narrowing of the ventricles, and a remarkable dryness of the whole organ with its membranes, the change involving both the cerebrum and cerebellum, and accompanied with an increase of weight, all indicating increased nutrition, or the deposit of new matter in the tissue of the brain. Thinning of the cranial bones may attend this condition, increased internal pressure resulting in their partial absorption. The causes of this form of disease are not generally understood. The symptoms, though always present, are not uniform. Among them may be mentioned intense head-aches, a weakened or perverted state of the intellectual faculties, fits of giddiness, accompanied with stupor; finally, convulsions, with perhaps loss of sensation and motion, the patient being unexpectedly cut off by an epileptic attack. The disease has not been observed in persons over fifty. In most cases, the patients were between twenty and thirty. In one instance, however, it was developed in a young girl of thirteen. Lead poisoning would seem to be an exciting cause, it having, in several instances, been developed in painters and manufacturers of white lead.