54 BACTERIOLOGY. 



acid and water, it affords 3,939 heat-units or 

 calories ; if, however, it be split into butyric 

 acid, hydrogen and carbon dioxide, it yields 

 only 414 calories. One thousand grams of 

 sugar suffices to produce 3,939 calories by 

 means of complete combustion with oxygen, 

 while by means of the above-mentioned decom- 

 position without oxygen 9,514.5 grams are 

 necessary to the production of the same num- 

 ber. The access of pure atmospheric oxygen 

 consequently makes life easy, but is not in- 

 dispensable. The energy needed for the pro- 

 cesses of life can be procured by simple decom- 

 position, by hydration or by loosening of poly- 

 merizations ; in none of these chemical actions 

 is access of free oxygen necessary, and all 

 molecular shif tings may take- place simply 

 with the help of chemically bound oxygen. If 

 we consider anaerobiosis from the point of view 

 of physics, then, it is seen at once that life is 

 carried on in accordance with the general laws 

 of energy and that there can be no especial vital 

 force. The maintenance of life without free 

 oxygen depends solely upon the presence or 

 absence of available substances which can be 

 broken up with sufficient ease. The standard 

 of availability, however, is very different for dif- 

 ferent microbes. Pasteur regarded sugar, Nae- 

 geli peptone, and Hueppe true proteid substance 



