=Atrophy.= In this condition, there is found a general diminution of the volume of the brain, and especially of the convolutions. The latter are shrunk, narrow, and sometimes softened, while the sulci are large and open, the brain receding from the skull, and the pia mater greatly injected with serous fluid, giving the appearance of a jelly-like investment to the whole brain. The brain substance is at the same time soft, the ventricles enlarged and filled with fluid, while a large amount of serum will flow from the sub-arachnoid space at the base of the brain, and from the spinal canal. While this condition of the brain might be looked upon as a result of pressure from the accumulated serum, the absence of the usual symptoms of hydrocephalus, with the known history of these cases, renders it quite probable that the change commences as an actual loss of brain substance, the place of the latter being supplied with serous fluid. Resulting from atrophy of the brain, there will often be found an increased thickness of the cranial bones, this being another conservative effort of nature to preserve the normal support and pressure upon the brain. Atrophy of the brain is sometimes found in old age and in various enfeebling diseases, where all the organs suffer more or less waste from improper nutrition, but it is so frequently found with drunkards, especially those who have died with _delirium tremens_, that this condition may, in the large majority of cases, be considered as the effect of intemperance. Several forms of atrophy may also be observed. It may be confined to some portion of the convoluted surface, or to one of the striated bodies or optic beds. Atrophy of the optic tracts, or nerves of one or both eyes, is not unfrequently associated with loss of sight from amaurosis. Tumors of the Brain. The brain, like other parts of the body, is subject to morbid growths of a great variety of forms. The symptoms of tumors in the brain, in many points, present such resemblances to other forms of disease, that it is usually the post-mortem alone, that will determine the fact of their presence or character. It may be said in general, however, that the effects of morbid growths in the brain will vary according: 1. To the changes in the surrounding cerebral substance; 2. To the size of the growth; and 3. To the position of the brain in which it may be developed.