BUTYRIC ACID BACTERIA 287 



them, although differing in name, are no doubt similar 

 organisms ; it will suffice to briefly describe the two 

 main species isolated and studied by Schattenfroh and 

 Grassberger, since these two species apparently include 

 most of the anaerobic forms which attack carbo- 

 hydrates. 



a. Species I., described as "motile non-liquefying Granulo- 

 bacillus saccharobutyricus," is apparently the same organism as 

 B. saccharobutyricus of Von Klecki, Granulobacter saccharo- 

 butyricum of Beijerinck, B. amylozyma of Perdrix, and is 

 closely allied to the pathogenic organisms B. Chauvoei, which 

 causes blackleg in cattle, and B. enteritidis sporogenes. 



It is common in water, soil, meals of various cereals, and com- 

 paratively rare in milk. 



The bacteria are rod-shaped, with peritrichous flagella; they 

 grow best under strict anaerobic conditions at 35 to 37 C. Clos- 

 tridia are formed containing oval spores, 1.8 to 2.3 /a, long and 

 1.3 to 1.7 & broad. 



The organism converts milk-sugar almost completely into 

 butyric acid, carbon dioxide, and hydrogen, little or no lactic 

 acid being formed; from grape-sugar, however, it forms both 

 acids. 



Proteins are not affected by it. 



Gelatine is not liquefied. In grape-sugar gelatine media stab- 

 cultures may exhibit three types of growth, viz., (a) A beaded 

 track with the organisms in the Clostridium form ; (b) a root-like 

 track, with fine .outgrowths ; (c) a turbid track, showing gas 

 bubbles, the organisms motile and without granulose. 



Grape sugar agar. In stab-culture much gas is produced, 

 and a strong smell of butyric acid. 



Potato. Extensive growth, white and frothy, with strong odour 

 of butyric acid. The bacteria contain much granulose. 



Milk. In milk butyric acid is produced, and casein, full of gas 

 bubbles, is precipitated, but not peptonized. 



