400 DESCRIPTION OF SOME SPECIES OF MILK BACTERIA 



with bad cheese or rancid butter 

 which has been placed in the 

 incubator, two organisms which 

 only show small deviations from 

 one another. {Cf. the B. saccharo 

 butyricus of Klencki from cheese.) 

 Kedrowski's B. acidi butyrici is a 

 motile bacillus, which towards one 

 end produces ellipsoidal spores. 

 The staining of the spores is readily 

 accomplished. The colonies in 

 gelatine show rays — those in agar 

 partly reticulated — and interlaced 

 spurs. Liquefaction of gelatine is 

 more or less marked. Milk is 

 coagulated with separation of serum 

 on the surface (acid reaction). 

 There is gradual peptonisation and 

 simultaneous gas development. 



Q-ruber's Butyric acid bacillus, No. 1, 



isolated by Gruber. Anaerobic. 

 Bacilli of 3 to 5 M long by o-6 to 

 0-8 /u. broad ; sometimes joined 

 together in threads. Before sporu- 

 lation they become swollen to 

 the thickness of 2 m. The spores 

 appear generally nearer to one end, 

 they are readily double-stained. 

 Colonies in gelatine are black- 

 brown. The organism produces 

 butyric acid and " Butylalkohol." 



Gruber's Butyric acid bacillus, No. 2 — 



Anaerobic. Bacilli 2 to 8 m long 

 by -5 /A broad ; curved in comma or 

 sigma shape. Before forming 

 spores they become enlarged in all 

 dimensions. Spores 1-5 m long by 

 •8 M to I -o /i broad. The colonies are 

 round or slightly uneven, at first 

 faintly yellowish, then yellow-brown 

 and roughly granulated. Gas pro- 

 duction. 



Gruber's Butyric acid bacillus. No. 8 — 



A facultative anaerobe, differing 

 from the bacillus pseudo-butyricus 

 of Hiippe, in that it is spore-bear- 

 ing — bacillus 3 /x to 5 M long by o-6 

 M to o-S M broad. During sporula- 



tion the bacilli swell up to twice 

 or thrice their breadth, in spindle 

 and citron shape — medial spores of 

 variable size are formed (maximum 

 1-2 /tt to 2 /i). Dwarf spindles with 

 spores are frequent. In gelatine 

 colonies round, resembling a ball. 

 Gelatine liquefied. Fermentations 

 same as in Nos. i and 2 of same 

 worker. 



BUTTER BACIIiliUS OP 

 RABINOWITSCH 



(Petri-Rabinowitsch), 1897. 



Source and habitat — Butter. 



Morphology — Same form as tubercle 

 bacillus, but thicker and often 

 clubbed. Isolated, or ranged 

 parallel to one another — at times 

 in forms of long non-ramified 

 filaments. 



Staining reaction — Ziehl-Neelsen, or 

 method of Ehrlich, and remains 

 coloured by Gram's method. 



Motility — Non-motile. 



Biology : cultural characters {includ- 

 ing biochemical features). 



Bouillon — Renders bouillon tur- 

 bid and acid eventually, but at first 

 the bouillon remains clear ; produces 

 trace indol (Rabinowitsch) ; thick 

 wrinkled pellicle formed ; disagree- 

 able ammoniacal odour. In glucose 

 bouillon the pellicle is very marked. 

 H.2S is produced in bouillon. 



Gelatine plates — Slow grpwth ; 

 small granular colonies ; transparent 

 periphery, becoming opaque later ; 

 non-liquefying. 



Agar plates and tubes — Grows 

 very well, especially on glycerine- 

 agar. Golden or copper coloured 

 film, much wrinkled, moist, thick, 

 creamy {see frontispiece); glistening 

 appearance ; somewhat unpleasant 

 odour. After much subculturing be- 

 . comes dry, and loses its creamy and 

 moist appearances. On magnifica- 

 tion granularity visible. Agar 



