THE PROBLEMS PRESENTED
The cerebrospinal fluid has of late years acquired a peculiar importance. This is true not only because of the rôle it has assumed in neurologic diagnosis, but also because of the various attempts that have been made to utilize it as a vehicle of therapeutic administration, or rather, because of the various procedures that have been evolved to use the subarachnoid space and the other containers of the cerebrospinal fluid as avenues of medication. Perhaps it will not be out of place to review some of the facts in regard to its physical and chemical constitution; in regard to its location and distribution; in regard to the laws of physics which it must obey; in regard to its source, it renewal and its escape; in regard to its relation to the vascular and lymphatic systems; in regard to the pressure under which it exists, and, finally, in