During the last few years I have examined a number of cerebrospinal fluids from lumbar punctures. The analyses are of some interest, as they throw light on such disputed questions as the molecular concentration and the nature of the proteids. In other respects they may serve to enlarge somewhat the already existing knowledge of this fluid. The specimens were usually not analyzed until a day or two after they were drawn, but they were received and preserved in sterile flasks, kept very cold. The first four cases were furnished by Dr. C. J. Aldrich, from patients with febrile temperatures. The last fluid was given me by Dr. C. E. Briggs. I wish to take this opportunity of thanking these gentlemen for the material. SUMMARY OF ANALYSES. The results of the analyses are briefly as follows: Appearance. —Fluids I to IV, are perfectly clear and colorless, III containing a very small