96 ATLAS OF BACTERIOLOGY. 



//. Strict Anaerobics. Growth and sporulation 

 take place only during complete exclusion of oxygen. 

 This class includes bacillus cedematis maligni, bacil- 

 lus tetani, bacillus Chauvoei, and a large number of 

 inhabitants of slime and earth. When exposed to the 

 free oxygen of the atmosphere the vegetative forms of 

 these bacteria perish very readily, but the spores ex- 

 hibit great resistance to oxygen. As the anaerobics 

 are excluded from the main supply of energy which 

 is at the command of aerobic bacteria (oxidation of 

 the absorbed nutritive material by means of free oxy- 

 gen) , they must rely upon nutritive substances which 

 possess great potential energy and which, like grape 

 sugar, for example, set free energy (heat) by separa- 

 tion into two smaller molecules (for example, alcohol 

 and carbonic acid ; or acetic and lactic acids) . Hence 

 anaerobics are almost always cultivated upon gelatin 

 or agar which contains one to two per cent of grape 

 sugar. 



///. Facultative Aerobics and Facultative Anae- 

 robics. The large majority of the bacteria which, as 

 a rule, are cultivated aerobic (including almost all 

 the pathogenic forms) tolerate a restriction in the 

 supply of oxygen without suffering injury or ex- 

 hibiting diminished growth. In many cases life 

 in the animal body, for example in the intestinal 

 canal, decidedly involves a diminution or aboli- 

 tion of the supply of oxygen. When oxygen is 

 excluded the formation of pigment is almost al- 

 ways abolished, while virulent products of dis- 

 assimilation are produced in greater abundance 

 (Hiippe). 



It is a very important fact that recent investigations 



