MECHANISM OF DEATH 311 



while moist cells would be killed at these temperatures in a few 

 minutes or even seconds. If the coefficient should decrease over 

 this range, the resistance of dry bacteria at high temperatures would 

 be still greater than calculated. 



This also enables us to compute the time for sterilizing at lower 

 temperatures dry glassware or other dry materials which cannot 

 stand the customary high heat of 160°C. for thirty minutes. With 

 a temperature coefficient of 2.5 (this coefficient has really never been 

 determined for dry spores), it would require at 100°C. about 30 X 

 2.5^ minutes = five days two hours to obtain a sterilizing efficiency 

 equal to thirty minutes at 160°C. 



It is generally known that the material on which 

 bacteria are dried has a great influence on their via- 

 bility. Bacteria dried on coverslips die very readily, 

 while those dried in soil remain alive over a long period. 

 The bacteria of legume nodules can be cultivated from 

 herbarium specimens after years, while the attempt to 

 use, commercially, cultures dried on cotton proved to 

 be a failure. A large amount of time has been spent 

 in searching for paints or finishes for walls of hospitals 

 and operating rooms which would kill in the shortest 

 possible time any bacteria smeared on them. But no 

 quantitative work has been done in this respect except 

 just a measurement of the time required to kill all 

 bacteria spread and dried on certain strata. No experi- 

 ments which try to explain the different death-rates 

 on different strata from the viewpoint of death as an 

 oxidation process are known to the author. 



A very interesting and important question has never 

 been solved or attacked, namely, the cause of death of 

 dry bacteria in the absence of oxygen. It is barely 

 possible that bacteria remain alive for infinite times in 

 the absence of oxygen. Lipman (1931) has succeeded 

 in demonstrating living bacteria in coal. The rate of 

 death becomes smaller when we eliminate the main 



