MECHANISM OF DEATH 



385 



shown to occur, oxidation in the case of dry cells, 

 hydrolysis (or some similar reaction with water) in 

 death by heat. 



It seems easy to decide whether oxidation is a cause 

 of death; in this case, starvation should not kill the cells 

 so rapidly in the absence of oxygen. Such experiments 

 (p. 388) have shown Bad. coli to die more slowly in 

 the absence of oxygen, while starving Bad. typhosum 

 died more readily without oxygen. If these experiments 

 can be considered representative, oxidation may be the 

 main death cause of some bacteria, and not of others. 

 This agrees with our experience that some bacteria are 

 killed by oxygen even in the presence of food, namely, 

 the obligate anaerobes (see also p. 203). 



Oxidation might then be the cause of death of starving cells of 

 Bad. coli. Something is oxidized in the cells which, in normally 

 nourished cells, would be reduced again. Reductions require energy; 

 energy requires food. 



Table 127. — Rate of Death of Micr. pyogenes at Diffekent 

 Temperatures 



Typhoid bacteria die faster without oxygen. An hydrolysis is 

 probably the cause, which, in air, can be counteracted by the cells 

 for a while, but not in the absence of air. Possibly, Bact. typhosum 

 has some reserve substance which can be utilized only with oxygen, 

 as e.g., fat. 



