INFECTIONS OF THE DIGESTIVE TRACT 117 



bald Smith. Anaerobic organisms in general grow much 

 better in the closed limb of the tube on sugar bouillon 

 in the presence of bits of sterile tissue (such as liver from 

 a guinea-pig or rabbit), and in some cases, as in that of 

 B. aerogenes capsulatus, they do not grow in the ab- 

 sence of this aid. The identification of the anaerobes 

 involves the study of their cultural characteristics, of 

 their ability to form gas on sugar media, and the de- 

 termination of their gas formula. The estimation of 

 the ratio between the hydrogen and the carbon dioxide 

 formed is an important point in identification first 

 suggested by Theobald Smith. It is easy to determine 

 this point by adding caustic potash to the contents of 

 the fermentation tube, this being followed by absorp- 

 tion of the carbon dioxide. 



The influence of the growth of anaerobes upon milk, 

 especially litmus milk, is easily studied in the fermenta- 

 tion tubes and gives considerable aid in identification. 

 For example, B. aerogenes capsulatus quickly makes acid 

 on milk and sets up a stormy fermentation due to the very 

 rapid production of gas from milk-sugar. It also acts 

 proteoclastically on the casein, and the coagulated milk 

 is partly digested and broken into small masses. This 

 behavior is in marked contrast to that of the bacillus 

 of malignant oedema. Very rapid and abundant gas 

 production from milk occurs through the agency of B. 

 cloacce, an organism not rarely found in the human 

 intestine. 



The pathogenicity of the isolated anaerobes is also 

 a point of importance in the establishment of their 



