Evidence of a staphylococcal neurotoxin.

It is evident that the addition of 15 mg NaCl per ml of basal medium, with L. leichmannii (strain ATCC 7830) as the test organism, gave rise to a valid sloperatio assay at higher concentrations of vitamin Bu. In the case of one of the samples studied, this alteration was the means of obtaining results in statistical agreement with those obtained using L. leichmannii (strain ATCC 4797) and in good agreement with the spectrophotometric evaluation. The significant difference between methods in the case of sample N may possibly have been related to the proportion of vitamin B2b which has been estimated at approximately 60 per cent of the vitamin content. Sample P contained only cyanocobalamin. Further experiments are being planned to test this possibility. The sponsorship of this work by M. E. Avery and the technical assistance of G. Holstein are gratefully acknowledged.