Abstract
Additive tests of mononucleosides on the growth rate of various strains were first carried out for L. leichmannii assay of vitamin B_<12>, using thymidine, inosine, adenosine or guanosine. Positive effect was seen by an addition of thymidine, but was more effective by additions of both vitamin B_<12> and thymidine. Additive tests of both vitamin B_<12> and various ribonucleosides to Skeggs' modified medium were found to accelerate the growth rate of the strain in 3-4 hours less than a single addition of vitamin B_<12>, while effects were scarcely observed by a single addition of the ribonucleosides. In L. arabinosus assay of pantothenic acid, additive effects of the ribonucleosides were scarcely recognized, on the contrary, they rather acted inhibitory on the growth. In Stc. faecalis R assay of folic acid, positive influence of thymidine on the growth of the strain was always demonstrated, and more effective by addition of both folic acid and thymidine. Concerning the addition of both vitamin and ribonucleoside, detectable influence was always found. In Sacch. carlsbergensis assay of vitamin B_6,marked response of ribonucleosides on the strain was also observed.
