IlL RELATIONSHIP BETWEEN A VARIETY OF SACCHAROMYCES CERE- VISI2E AND THE TYPE i"I VARIETY OF DIPLOCOCCUS

The present paper reports evidence of an immunological relationship between one variety or type of the yeast Saccharomyces cerevisi~e and the Type II variety of Diplococcus pn,umoni~e (Pneumococcus). The immunological interrelationships among the different yeasts have never been well established, but it is certain that all of the yeasts included by the species term Saccharomyces cerevisi~ are not immunologically identical. Only one strain or variety was used in most of our investigation. Experiments were made with a number of the recognized varieties of the species, that differ from each other in fermentation and other cultural properties, but the present data are not sufficient to furnish definite proof of the possession or lack of serological relationship of these other yeast varieties to Type II pneumococci. I t is necessary, therefore, to limit the present paper to the relationship exhibited by one variety of Saccharomyces cerevisi~e that was derived from commercial (Fleischmann's) dried yeast. The immunological relationship between the yeast and the Type II pneumococcus may be reported by the presentation of two kinds of data: (1) the reactions of the yeast with Type II antipneumococcus serum; (2) the reactions of Type II pneumococci with the antiyeast serum. In the following report the reactions of the yeast with the antipneumococcus serum are presented first, although the evidence