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siderably. When they do not ferment raffinose, then in most cases they will not ferment 

 salicin either. The betacocci do jiot 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 betacocci. 

 The power of fermentation generally declines somewhat in course of time, not only as 

 regards lactose, but also for maltose and rallinose; even, indeed for their favourite foods, 

 such as sacchaiose and pentoses, and the source of nitrogen employed often exerts a quite 

 remarkable influence. Yeast extract, for instance furthers the fermentation of raflijiose 

 in Nos. 4, 6, and 9, but retards it in No. 33. Similarly, it furthers the fermentation of cane 

 sugar in No. 37, but retards it in Nos. 33 and 35. The betacocci which in a natural state 

 (i. e. freshly isolated from vegetable matter) ferment both pentoses as a rule, however, 

 prefer arabinose. Which is best seen when using an inferior source of nitrogen (W); examp- 

 les of this are Nos. 13, 14, 15, and 16. In accordance with this, they are more easily liable 

 to lose the power of fermenting xylose than arabinose, and the A-forms are therefore nearly 

 related to the A + X-forms. It may happen that the A-forms also lose the power of fer- 

 menting arabinose, and of the three strains from the same cheese (Nos. 7, 8, and 9) which 

 Were at first entirely alikewith regard to their action upon the pentoses, two simultaneously 

 lost the power of fermenting arabinose, while the third, vvhich differs from the others in 

 fermenting salicin, has still retained this power. One of those which lost the power of fer- 

 menting arabinose, on the other hand developed, its power of fermenting xylose, so that 

 it has really become transformed from an A-form to an X-form. The explanation is doubtless 

 this that these bacteria in reality possess the power of fermenting both pentoses, and it 

 is more or less a matter of chance which of them they are better able to deal with at the 

 moment (cf. also Nos. 6 and 12). 



For the same reason, also, it is difYicult to draw any sharp limit between the true 

 X-forms (which ferment xylose, but never any considerable quantity of arabinose) and 

 the foregoing. The X-forms have only slight slimy growth in cane sugar gelatin, and never 

 liquefy it. They may, however, be found to lose the power of fermenting xylose, becoming 

 at the same time strong slime-formers. By continued re-inoculation of No. 33 in cane sugar 

 gelatin, we succeeded, for instance, in producing a variety which resembled No. 40 in 

 nearly all respects. From this we may conclude that the 0-forms are closely related to the 

 X-forms. 



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

 indistinguishable from the streptococci. Morphologically also, they resemble the latter 

 (PI. XXI— XXIV), though the faculty of dividing in two directions is often more developed. 

 The A- and A + X-forms, when cultivated in broth or milk, make shorter or longer chains, 

 and closely related strains may differ in this respect. No. 11 (PI. XXII), for instance, 

 forms long chains, whereas No. 12 (PI. XXI) appears chiefly as a diplococcus. WHien the 

 betacocci are cultivated on gelatin, they form as a rule only short chains. The X- and 0- 

 forms will often appear as rods on agar streak (Nos. 33 and 36. PI. XXIII), or as micro- 

 cocci (No.35,Pl. XXIII)!), jn fiuifi substrates also, they can assume this irregular appear- 



On agar streak, the one (No. 33) of two related strains can form rod-shaped cells, and the 

 other (No. 35j cells of the micrococcus type. We noticed the same thing in the case of Sc. Uquefaciens. 



n. K. D. Vidensk. Selsk. Skr., naturvidensk. og mathem. Afd.. 8. Række. V. 2. 20 



