374 



MILK 



and boiled milk in which the spores survived. The author came 

 to the conclusion after experiments with animals that toxins are 

 produced by these organisms, and that consequently the digestive 

 tract is injured, especially in infants. 



Anaerobic spore-bearing bacteria cause butyric acid and pro- 

 pionic acid fermentations in milk. In addition to these acids, 

 valeric acid is sometimes formed, and the milk always emits a 

 disagreeable odor under the influence of these bacteria. The buty- 



Fig. 177. Anaerobic spore-bearing bacteria (Weigmann). 



ric acid bacteria are widely distributed in cultivated soil, ma- 

 nure, on grain, and some fodder. The spores are terminal and a 

 drumstick or clostridium-shaped large bacillus is seen in stained 

 preparations (Fig. 177). 



The butyric acid bacteria are sometimes separated into the 

 motile and the non-motile varieties. The motile butyric acid 

 bacillus, named Granulobacillus saccharobutyricus mobilis or 

 Bacillus saccharobutyricus, is not as common in milk as the 



