NON-PATHOGENIC MICROCOCCI. 619 



236. LETJCONOSTOC MESENTEROIDES (Cienkowski). 



Synonyms. Froschlaichpilz ; Pilz der Dextrangarung. 



Found upon the beet juice and the molasses of sugar factoi'ies, where it 

 develops as large, jelly-like masses resembling frog spawn ; also upon raw 

 or cooked carrots or sugar beets. 



Morphology. The reproductive elements are spherical or oval, and from 

 1.8to2ju in diameter; they consist of a firm, membranous envelope with 

 shining contents. When these germinate according to Van Tieghem the 

 external layer of the cell wall is ruptured in an irregular way and a middle 

 layer is extruded to form a thick, jelly-like envelope, while the inner layer 

 remains in contact with the protoplasmic contents of the cell ; the cell and 

 its envelope then become elongated and binary division of the reproductive 

 element occurs; this process is repeated in the segments, and as a result a 

 chain of spherical elements enclosed in a sausage-shaped mass of jelly is de- 

 veloped ; later the chains become curved and break up into longer or shorter 

 fragments, which are enclosed in an irregular gelatinous mass ; these zoog- 

 Icea crowded together form small masses having a parenchymatous struc- 

 ture ; these adhere to each other when they come in contact, and when dis- 

 tributed in a liquid may be brought together by shaking to form a large, 

 Jelly-like mass which ha's apparently been developed by the process of shak- 

 ing, as the smaller masses suspended in the fluid could not readily be seen. 

 The zoogloea masses have a cartilage-like consistence and can be cut into 

 sections with a razor. The jelly is hyaline, but in beet juice often has a gray- 

 ish color from the presence of impurities attached to its surface. When 

 treated with a solution of haematoxylon it acquires a brown color. After 

 some time the jelly is dissolved, and the cocci are set free and in a suitable 

 medium again develop zooglcea. Van Tieghem has demonstrated the forma- 

 tion of spores. These are formed when conditions are no longer favorable 

 for the development of the vegetative cells ; here and there a cell in a chain is 

 seen to increase in dimensions, and in the interior of this mother cell a con- 

 siderable number of refractive spores are developed. 



Biological Characters. This coccus is aerobic. It is readily cultivated 

 in liquid media containing glucose. According to Van Tieghem, it appro- 

 priates grape sugar directly and cane sugar indirectly i.e., after it has been 

 changed into grape sugar by a ferment produced by the coccus. Development 

 is very rapid under favorable conditions. Thus Durin reports that a wooden 

 tub in which beet juice had been kept, and upon the walls of which a thin, 

 slimy mass of this microorganism remained attached, was filled with a neu- 

 tral solution of molasses containing ten per cent of sugar. At the end of 

 twelve hours the entire contents of the tub had been changed into a compact, 

 jelly-like mass by the development of Leuconostoc mesenteroides. The 

 chemical formula for the jelly is CnHioOio. 



