476 ANAEROBIC BUTYRIC-ACID FORMERS 



1. Motile butyric-acid bacteria. 



2. Gas formers of the black-leg bacillus type, (a) Spore-forming 

 (black-leg bacillus, Bacillus aerogenes capsulatus); (6) non-motile 

 (non-pathogenic) butyric-acid bacilli. 



3. Organisms of the type of the malignant edema bacillus. 



4. Putrefying butyric-acid bacilli of the type of Bacillus putrificus 

 Bienenstock. 



The motile butyric-acid bacillus is relatively prevalent as a sapro- 

 phyte in soil, water, grain, flour, cheese, more rarely in milk, which 

 generally does not form a favorite soil for its development. It grows 

 best, according to Beyerinck, in artificial culture in. a 5 per cent. 

 peptone solution (under anaerobic conditions). It is a long, slender 

 rod, motile, and with flagella surrounding the entire body. Before 

 sporulation the bacillus forms granulose 1 from starch in its interior 

 and assumes the clostridium shape. The spore escapes from its 

 membrane generally at one end, and the empty shell may for some 

 time remain over one end of the young bacillus like a cap. The 

 spores are killed when exposed in boiling water for three minutes to 

 100 C. On gelatin the organism forms cloudy, hazy colonies; the 

 colonies may also be better defined and surrounded by filamentous 

 excrescences or they may form a veil on the surface of the medium 

 without any distinctly defined boundaries whatever. The bacillus, 

 while fermenting dextrose, saccharose, lactose, starch, and glycerin, 

 and forming from them butyric acid, lactic acid, carbon dioxide, and 

 hydrogen, does not split up albumin. Butyric acid is formed in 

 excess of lactic acid and hydrogen in excess of carbon dioxide. In 

 milk a floating layer of casein full of gas-bubbles is formed. This 

 motile butyric-acid bacillus is identical with the bacilli described 

 under the following names: Bacillus amylobacter I and II, Gruber, 

 Granulobacter saccharobutyricus Beyerinck, and Bacillus saccharo- 

 butyricus of Klecki. 



The non-motile butyric-acid bacillus is likewise frequently found 

 in nature, and as it is a regular inhabitant of the feces of cattle, often 

 in milk. According to Botkin-Rodella it can be easily obtained by 

 inoculating sterile milk covered by a cream layer 10 cm. high from 

 garden earth. The milk, while still heated to 70 C., is inoculated 

 and then kept in the incubator, when the non-motile bacillus generally 

 grows abundantly. The organism occurs in two types. The first 

 type presents cylindrical rods, with rounded ends, generally forming 

 chains of three to six links, or pseudofilaments 20 to 50 micra long. 

 Its colonies are small, very shining, and surrounded by numerous 

 excrescences. The second type forms shorter and more slender rods, 

 rarely arranged in longer chains, and its colonies are round, sharply 

 defined, smooth, and dewdrop like. Both types in starch-agar form 



1 Granulose formed from starch in the interior of the bacilli of this group like starch stains 

 blue with iodin solution. 



