x.] BACILLUS. bl 



zooglcea, and is anaerobic, since it grows well and forms spores 

 copiously even when not exposed to the air. After the rods 

 have gone on dividing and forming chains and filaments for 



FIG. 46. CLOSTRIDIUM BUTTBICUM OR BACILLUS BUTTRICXJS. 

 Some of the spindle-shaped forms include an oval spore. 



some time, they swell up, become granular and oval with 

 more or less pointed ends, and the formation of oval spores 

 sets in. In this state the oval rods are about 0-002 to 0'003 

 mm. thick, and the spores are about 0*002 to 0'003 mm. long 

 and O'OOl mm. thick. In solutions of starch, dextrin, and 

 sugar the bacillus forms butyric acid. The fermentation of 

 butyric acid in old milk and ripening cheese is due to this 

 bacillus. Cellulose is decomposed by it, and hence its great 

 importance in the digestive process of herbivorous animals, 

 in whose stomach and intestine it is very common. It is very 

 common also in substances containing starch. 



Iodine produces a characteristic blue staining in the proto- 

 plasm of the bacillus. In young rods the colour produced by 

 iodine is blue, in older rods it is violet. 



E. Kern described (Biolog. Centralbl. ii. p. 135) a bacillus 

 under the name of dispora caucasica, which he found in the 

 Caucasus, and which is used as ferment to produce from cow's 

 milk a peculiar drink called "kephir" or "hpypo." The 

 bacillus is similar to the bacillus subtilis, but is distinguished 

 from it and all other bacilli by this, that every bacillus forms 

 two spores, one at each end, hence the name dispora. But 

 after recent investigations it appears that this bacillus is 

 accidental, the fermentation being produced by saccharomyces 

 inycoderma (see Chapter XIV.). 



Pigment bacilli. 



(a) Bacillus ruber. 1 This appears as minute rods, isolated or 



1 Colin, Frank. Beitr. x. Biol. d. Pflanzen, vol. iii. p. 181. 



G 



