The first volume of the system deals with normal and pathologic ganglion cells, nerve fibers, their endings and the nerves of the blood vessels. The second volume treats with mesodermal tissues of the brain, including microglia, meninges, choroid plexus and blood vessels; in another part of this volume are discussed the pineal gland, hypophysis, optic nerve, retina, choroid and papilla. The third volume is largely taken up with tumors, malformations, with which are included tuberous sclerosis, amaurotic family idiocy, Schilder's and Pelizaeus-Merzbacher's diseases and hydrocephalus.
The topics mentioned are only a few of the numerous phases of neuropathology and normal histology of the central and peripheral nervous systems. The most interesting and elaborate contribution is that of del Rio Hortega. It deals with the form of supportive connective brain tissue known as microglia, the cells of which are termed microgliocytes or Hortega cells. These represent the reticuloendothelial system of the