150 



72 



consequently not from dextrose, as has been asserted by Liesenberg and Zoff^). Neither 

 do they form any trace of slime with equal parts of the two components of saccharose, 

 dextrose and lævulose. Acccording to Beijerinck"^), the slime consists of dextran. As 

 shown in Zettnow's illustrations (PI. XXIV), it proceeds from the cell wall. It is for- 

 med more rapidly with 5 — 10% cane sugar than with 2%. In liquids with less than 

 2 % cane sugar, the slime formation is only slight. Cane sugar broth becomes at first 

 slimy all through, and some few strains keep at this stage for several months (chiefly X- 

 and 0- forms), whereas in the case of other strains, the slime soon contracts, so that zoo- 

 gloea masses are formed at the bottom of the flask. On cane sugar agar, the slime deve- 

 lops but poorly, but appears in a very characteristic manner on cane sugar gelatin. 

 Large colonies, clear as water, appear on the plates, resembling the colonies of certain 

 aerogenes species (the slimy aerogenes forms produce, however, slime from all the su- 

 gars which they ferment) and in stabs, we get very characteristic pictures, as shown 

 in the photographs on PI. XXV. Though these bacteria do not liquefy ordinary ge- 

 latin, and are not provided with other proteolytic qualities, several of them can, after 

 some length of time, liquefy cane sugar gelatin, which figure is indicated in the tables 

 by I {liquareY). 



As the genus Betacoccus contains all possible degrees of sliminess and liquefying 

 power, we cannot attach too much importance to these characteristics, and we may find 

 cases where of two strains, otherwise entirely alike (as Nos. 38 and 39, which were, more- 

 over, found in the same sample of material), one will liquefy and the other not. 



When isolated from vegetable matter, the betacocci thrive as a rule but poorly in 

 milk; when isolated from milk, on the other hand, or from dairy products, and sometimes 

 from dung, they can form comparatively large quantities of acid in milk, and even dissolve 

 some casein (Nos. 29 and 34). The power of souring milk, however, is comparatively soon 

 lost, but can be regenerated by continued transference from milk to milk. The bacteria are 

 often abundantly supplied with lactase, and it may happen that nearly all the lactose 

 of the milk is hydrolysed without any considerable quantity of it being fermented, which 

 shows that the proteins of the milk are a poor source of nitrogen for them. In contrast 

 to the streptococci, they thrive at least as well with yeast extract as with casein peptone 

 as source of nitrogen. When isolated from beets, they prefer beet juice to casein peptone 

 (Nos. 11 and 12, PI. XXV). 



The betacocci exhibit a certain preference for pentoses. Strains isolated from vege- 

 table matter for the most part ferment both xylose and arabinose, whereas those isolated 

 from dung, milk, or dairy products, will as a rule ferment only one of the two, or sometimes 

 no pentoses at all. Of the hexoses, they often prefer lævulose, and of the disaccha- 

 rides, often saccharose. They frequently ferment raiïinose, but of true polysaccharides, 

 only a little dextrin at the outside. With regard to salicin, the dilïerent strains vary con- 



M Beiträge zur Physiologie und. Morpliologie niederer Organismen. Leipzig 1893, Heft 1. 



■1 Folia microbiologica 1912, I, Heft 4. 



Zettnow distinguisiies between two types of Sc. mcsenteroides, Opalanitza and Aller, wliicli, 

 though it is not staled, undoubtledly correspond to the non-liquefying and liquefying betacocci 

 respectively. 



