GENERAL SYSTEMATIC BACTERIOLOGY 239 



ordinary cane sugar agar, the slime develops 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 sugars which they 



ferment) and in stabs, we get very characteristic pictures Though 



these bacteria do not liquefy ordinary gelatin, 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 1 {liquare). 



As the genus Betacoccus contains all possible degrees of sliminess and liquefy- 

 ing 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, moreover, 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 trans- 

 ference 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 hydrolyzed 

 without any considerable quantity of it being fermented, which shows that the 

 proteins of the milk are a poor source of nitrogen. When isolated from beets, 

 they prefer beet juice to casein peptone (Nos. 11 and 12). 



The betacocci exhibit a certain preference for pentoses. Strains isolated 

 from vegetable 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 laevulose, and of the disaccharides, often saccharose. They frequently 

 ferment raffinose, but of true polysaccharides, only a little dextrin at the outside. 

 With regard to salicin, the different strains vary considerably. When they do 

 not ferment raffinose, then in most cases they will not ferment salicin either. The 

 betacocci do not as a rule attack alcohols to any perceptible degree ; only a few 

 strains ferment a little mannite (No. 20 even a little sorbite). 



No other bacteria have proved so variable with regard to the sugars as the beta- 

 cocci 



Without cane sugar, the betacocci form small colonies, and are in all cultural 

 respects indistinguishable from the streptococci. Morphologically also, they 

 resemble the latter though the faculty of dividing in two directions is often more 

 developed 



The above mentioned morphological differences between the AO and A -\- 

 X-forms on the one hand, and the X- and 0-forms of the other, render it likely 

 that we have here to deal with two distinct species. As the former always (at 

 any rate unless in a weakened state) ferment arabinose, we will term them Beta- 

 coccus arabinosaceus, and as the latter (especially the typical X-forms) can be 

 isolated from most cowdung after enrichment in acid sugar broth, we will call 

 them Betacoccus bovis. As the betacocci are for the most part known under the 

 name of Streptococcus mesenteroides, it would have been reasonable to use the name 

 Betacoccus mesenteroides for one of the species, had it not been that both comprise 



