THE GENUS ASCOCOCCUS 137 



reports that after an examination of 15 different strains of 

 Leuconostoc, during a period of ten years, he has been un- 

 able to find a single one which possessed the high resistance 

 to heat and to calcium chlorid noted by Liesenberg and 

 Zopf. Two strains which were carefully worked out by 

 'Zettnow failed to form zooglcea in dextrose solutions and 

 differed from the type described by Liesenberg and Zopf in 

 certain minor characteristics. They formed an almost in- 

 visible growth on potato, failed to grow in asparagin solu- 

 tions, and did not liquefy gelatin. Their reaction to the 

 Gram stain was apparently negative, isolated cells being 

 decolorized, while those in thicker masses retained the stain. 

 The two strains studied by Zettnow differed only in slight 

 details of colony formation, but one of them failed to agglu- 

 tinate with the serum of a rabbit injected with the other. 



The important differences between the earlier descrip- 

 tions and those of Zettnow appear to lie in the high resist- 

 ance to moist heat and to calcium chlorid, and in the 

 zooglcea formation in dextrose solutions, recorded in the 

 former. In the absence of evidence confirming the obser- 

 vations of Liesenberg and Zopf these points may be left 

 in abeyance. In other respects a single species of Asco- 

 coccus seems to be indicated. This may well bear 

 the name of Cienkowski's original type, Asc. mesen- 

 teroides. In view of the published descriptions of vari- 

 ous observers it may be characterized as follows : 



1. Asc. mesenteroides (Cienkowski). A coccus occur- 

 ing commonly in pairs, or chains of paired elements. 



