I. In the incubational test on several human feces using human feces medium treated with SM., the following two cases are observed:
1) Yeast like bacteria are seen to increase extraordinary.
2) The increase of yeast like bacteria can not be seen, but numerous anaerobic bacilli, especially gram positive bacilli are detected.
On the other hand, even in case anaerobic bacilli are not detected, it can be recognized that the extraordinary increase of yeast like bacteria is remarkably checked by the administration of drug resistant Str. fecalis.
II. The crossing incubational test on two kinds of human feces different in anaerobic bacilli flora in mediums made from each kind of feces above shows that, in the medium made from feces including many anaerobic gram positive bacilli, the same bacilli can not increase, and the extraordinary increase of yeast like bacteria is observed.
According to the result, it can be inffered that anaerobic gram positive bacilli have cheking power on the increase of yeast like bacteria.