An Investigation of the Absorption of Ultraviolet Light by Cerebrospinal Fluid in Various Disease States.

THE examination of cerebrospinal fluid in various diseased states has become a matter of routine investigation and at times yields information of great value in particular cases-for instance, the presence of a cellular content of over 3 per c.mm. leads to a suspicion of some infective process involving the central nervous system, and the preponderance of a mononuclear type of cell suggests the probability of such infection being of a granulomatous nature, syphilis or tuberculosis. Further, an increase in the protein content of the fluid is indicative of chronic infection, while reduction in the amount of sodium chloride present below 06 per cent. is almost pathognomonic of tuberculous meningitis. Of the more recent tests used in the examination of cerebrospinal fluid the precipitation of gold from a colloidal suspension of gold chloride is of peculiar interest. It appears to be an extremely sensitive test and to possess a definite diagnostic value. It is not necessary to refer in detail to this test; suffice it to say that it appears to depend on the upset of the balance of electric charges on the colloid particles in the gold solution with consequent precipitation of metallic gold. Lange's work at first seemed to suggest that in this method was to be found a specific test for neurosyphilis, since the highly albuminous fluids of general paralysis and tabes caused precipitation of gold in a manner which could be expressed as a simple curve. Other workers confirmed Lange's observations, but as the test became more widely recognized it was soon found that cerebrospinal fluids from cases other than neurosyphilis caused a similar precipitation, notably disseminated sclerosis. The test lost its specificity as a touchstone for neurosyphilis, but none the less the curves obtained are so characteristic that in association with other tests it is possible to say with considerable certainty whether a particular type of curve is caused by a fluid from a case of neurosyphilis or of disseminated sclerosis. PERSONAL INVESTIGATIONS