170 



92 



at least a couple of days, and as a rule from 3 — 5, or indeed often longer, to coagulate 

 the milk. It always attacks casein, though with varying strength, in the same manner 

 as the thermobacteria of milk, and is therefore of the greatest importance in the ripening 

 of cheese. Some few strains can for a time, though for no perceptible reason, render the 

 milk more or less slimy. One such slimy strain, of No. 34 (PI. XL), lost the power of fer- 

 menting cane sugar, though its power remained quite unimpaired as regards all other 

 sugars. Later, when its power of forming slime had disappeared, it at once regained the 

 faculty of fermenting cane sugar. 



Streptobaderium casei for the most part ferments galactose nearly as strongly as the 

 other monosaccharides, and lactose more strongly than the other disaccharides. Never- 

 theless We may find some few strains altmost or entirely losing the power of fermenting 

 lactose in artificial substrates (Nos. 5 and 23). Yeast extract will in many cases increase 

 the power of fermenting saccharose (Nos. 2, 3, 5, 12, 15, 17, 18, 19 and 26). A similar 

 effect is produced by this extract with regard to mannite, which is fermented — 

 albeit often only to a slight degree — by all streptobacteria. Nos. 27 — 34 ferment 

 sorbite and most of them also rhamnose, a little inosite and dulcite. As they, more- 

 over, form only dextro-lactic acid, and exhibit lively growth at 45°, they resemble 

 Streptococcus (jlyceiinaceus in almost all respects. Sbm. casei has no marked power of fermen- 

 ting pentoses or polysaccharides. Now and again we may discern a slight tendency to 

 fermentation of arabinose, more rarely xylose. No. 16, in the first years, fermented some 

 inulin, but lost this power after a time (its power of fermenting cane sugar decreasing 

 at the same time). 



Streptobacteiium casei (PI. XXXV— XL) forms, in broth, chains of short rods, with 

 the ends as a rule cut off straight. The chains have often sharp breaks, are as a rule very 

 long, and tangled, and then flake off, while the surrounding liquid is clear. The rods 

 can be so short that if rounded, they may resemble streptococci (No. 9, PI. XXXVII 

 and No. 28, PI. XXXVIII). They may, however, also grow out into longer rods, often 

 curved. In milk, the chains are as a rule shorter than in broth, and on solid substrates 

 as a rule even shorter still, but on the other hand, we often find longer rods here. On 

 agar (No. 34, PI. XL nethermost) and at times also in broth (No. 2, PI. XXXV) screwed chains 

 are often discerned; these arise by bending of the rods themselves. Even quite short rods 

 can be curved (Nos. 33, Pl. XXXIX, as here the layer of Indian ink is too thick the 

 bacteria appear too thin) and unite two and two with the concave side inwards, forming 

 rings or shapes of a deceptive likeness to that of the micrococci. These irregular shapes 

 are most frequently met with in the rhamnose and sorbite-fermenting strains which, 

 besides the qualities already mentioned (growth at 45° for instance) also dilTer from 

 the remaining strains by exhibiting livelier growth with 2 % common salt than with 

 only a trace of the same. There is thus much to advocate separation of these strains 

 as a distinct species, which might suitably be called Streptobaderium curvaium^), if it were 



') Miss Thoii.i Petkksson (now Mrs. Ai.mquist) has, in her "Studien über die Mikroorganismen 

 des Schwedischen Güterkäses" (C. f. Bakt II. Abt. 1904, Bd. XI, p. 137) already established a certain 

 species of lactic acid bacteria, Bacterium curuatum, distinguished by just these above-mentioned morpho- 

 logical qualities. One strain of this (No. 26) kindly furnished by the writer in question, exhibited lively 

 growth at 45°, but did not otherwise agree with my typical strains of Streptobacteriuni cunxttiim. 

 The extremelj- slight splitting dp of casein (only 3.2 "/o DN) might, however, seem to suggest that it 

 has degenerated on the whole during the long time of preservation. 



