DESCRIPTION OF SPECIES 



399 



spore formation — Oval spores at 37° 



C. ; mesially situated. 

 Biology : cultural characters {includ- 

 ing biochemical features). 



Bouillon — A pellicle is formed ; 

 bouillon remains clear. No indol. 



Gelatine plates and tubes — Small 

 whitish-yellow colonies with crater 

 shaped depression ; liquefaction ; 

 whitish grey wrinkled pellicle pro- 

 duced in liquid cultures in tubes ; 

 liquefied medium cloudy and yellow- 

 ish in colour. 



Agar plates and tubes — A thin 

 yellow layer, similar to B. mesen- 

 tericus. 



Potato — A fawn coloured trans- 

 parent layer, sometimes wrinkled. 

 Somewhat similar to B. mega- 

 therium. 



Milk — Is coagulated. Pre- 

 cipitated casein subsequently dis- 

 solved. Bitter taste. Butyric 

 acid produced from salts of lactic 

 acid ; also from milk-sugar when 

 it is previously hydrated. 



Facultative anaerobe. 



Non-pathogenic. 



BACHiliUS BUTYRICUS (Pasteur). 

 (Vibrion Butyrlque.) 



Source and habitat — Air, and thence 

 to milk. 



Morphology — Cylindrical rods with 

 rounded extremities ; 3 m to 5 /* 

 long by -6 m to -8 m broad. Isolated 

 or in chains ; at times in long fila- 

 ments indistinctly articulated. 



Staining reaction — Ordinary aniline 

 stains. 



Motility — Feebly motile ; motility 

 ceases at once in presence of free 

 oxygen. 



Spore formation — Ovoid spores. 



Biology: cultural characters {includ- 

 ing biochemical features). 

 Bouillon — Grows freely under 



strictly anaerobic conditions in 

 bouillon containing lactate of lime. 



Agar plates and tubes — In agar 

 " shake " cultures free from oxj'gen 

 the medium becomes clouded in 

 the lower portion, and is soon 

 broken up, with copious gas for- 

 mation accompanied by strong 

 smell of butyric acid. 



Gelatine plates and tubes — As 

 upon agar, but in a less degree, 

 the medium liquefying in the 

 neighbourhood of the forming 

 colonies. 



Anaerobic. 



Non-pathogenic. 



BACHjIiUS BUTYRICUS 



(Prazmowski). 



Source and habitat — Milk. 



Morphology — Rods ; sometimes appear 

 as unjointed threads ; sometimes 

 bent like vibrios ; 3 to 10 m long by 

 I y. broad. Sometimes in groups 

 in zoogloea. 



Staining reaction — Ordinary aniline 

 stains. 



Motility — Actively motile. 



Spore formation — Present ; rods swell 

 and become spindle-shaped or ellip- 

 soidal. 



Biology: cultural characters {includ- 

 ing biochemical features) — Grows 

 best between 35°-4o° C. 



Gelatine plates and tubes — Lique- 

 faction of gelatine ; a scum forms 

 on the surface. 



Milk — Butj'ric fermentation set 

 up. 



Non-pathogenic. 



Several other butyric acid organisms 

 have been isolated, of which a few 

 notes may be added : — 



Bacillus acidi butyrlci — (Kedrowski's 

 Butyric acid bacillus). Anaerobic 

 Kedrowski (Z. 16. 3) has isolated 

 from mixtures of sugar solution 



