The Lesions Produced in the Brain of Rabbits by the Injection of Indian Ink and of Argyrol.

IT hlas been shown that after the injection of organisms into the general circulation of rabbits definite lesions are found in the nerve-cell lamina of the brain'. These lesions are necrotic, but all areas are not involved to the same degree. The fornix shows the maximum of damage; here the necrotic lesion is definitely ischwemic. In the cornu Ammonis the ischamia is somewhat less absolute, while in the cerebral cortex groups of cells are necrotic, suggesting a partial local asphyxia, which is not so definite as that in the fornix or cornu Ammonis. The reason for these three varieties of local necrosis is to be found in the difference in the local vascular supply of each area. In the fornix the vessels are terminal; in the cornu Ammonis there is a partial anastomosis; while in the cerebral cortex there is a looped system of vessels providing a rich collateral circulation to any given area. Hence interference with the local vascular supply in the cortex does not result in ischsemia, but in a partial asphyxia, which may be compensated to some extent by the collateral circulation.