THE CEREBRAL CIRCULATION

Abstract

The existence of a vasomotor and chemical control of the vessels of the pia has been established by microscopic observation in the living animal,¹and it has been shown by perfusion experiments that volume blood through the brain as a whole may be influenced by similar factors.²It has not been known, however, to what extent the deeper vessels of the brain participate actively in the control of flow. Penfield³demonstrated the presence of nerve fibers in the walls of cerebral vessels, and Junet⁴and Clark⁵showed that the vessels of the choroid plexus also contain nerve fibers, possibly sensory in function. Stöhr⁶and also Schapiro,⁷investigating several mammals, noted a rich supply of nerves to the different structures of the choroid plexus. Findlay,⁸confirming earlier investigations of Chworostuchin, had already observed the presence of nerves in the choroid plexus ("It seems