DESCRIPTION OF SPECIES. 



503 



-grow out into long, apparently un- 

 jointed threads. They are mostly 

 actively motile, but also occur in 

 zoogloea. The rods and threads 

 are sometimes slightly bent, like 

 vibrios. They are anaerobic. The 

 shorter rods as a rule swell in the 

 middle, becoming ellipsoidal, lemon, 



''"O bQ cM 



Fig. 199.— Clostridium buttmoum. 



A. Active stage, (a, 6) Bent rods (vibrio- 



form) and threads. (c) Short 

 rods, (d) Long rods. 



B. Spore-formation. C. Spore-germina- 



tion. (Prazmowski. ) 



or spindle-shaped ; the long rods, 

 and sometimes the short ones, swell 

 At one end ; in either case ellipsoidal 

 spores are developed (Fig. 199). 



Cultivated in nutrient gelatine, 

 the medium is liquefied, and a scum 

 formed on the. surface. They grow 



best between 35° and 40° C. The 

 spores are widely distributed in 

 nature, and grow readily on fleshy 

 roots, old cheese, etc. They convert 

 the lactic acid in milk into butyric 

 acid, and produce the ripening of 

 cheese. 



They occur also in solutions of 

 starch, dextrine, and sugar, and are 

 the active agents in the fermenta- 

 tionof sauerkrautand sour gherkins. 



Bacillus butyricus (Botkin).— 

 Rods and filaments, spore-formation 

 present. They are anaerobic. 



Colonies consist of felt-hke 

 masses. 



Inoculated in the depth of gela- 

 tine with 1-6 per cent, of grape- 

 sugar, the growth commences in 

 the lower part of the needle track 

 with abundant formation of gas 

 bubbles and liquefaction of the 



Jelly- 



In milk there is abundant gas 

 formation, which will break the 

 fiasks if closed. 



They were isolated from milk, 



earth, and water. 



Bacillus butyricus 



q (Hueppe). — Rods slightly bent, 



■^ 21 fj, in length, -38 n in width, 



and filaments. 



Colonies yellowish ; rapidly 

 liquefying. 



Inoculated in the depth of 

 gelatine liquefaction occurs 

 along the track of the needle, and 

 later a wrinkled skin floats on 

 the surface. 



On agar the growth is yel- 

 lowish. 



On potato the growth is 

 wrinkled and faintly yellow. 

 They coagulate milk, precipita- 

 ting and then dissolving the casein. 

 They occur in milk. 

 Bacillus cadaveris (Sternberg), 

 — Rods 1-5 to 4 /x in length, and 

 1-2 ft in width, singly, in pairs, and 

 in filaments. 



They are anaerobic. Colonies in 

 glycerine-agar are irregular, granu- 

 lar, and white. 



They produce an acid reaction 

 in cultures. 



Subcutaneous injection in guinea- 

 pigs may produce extensive 



