MIYA, MARCUS AND PHELPS 



Universal Thermometer, type TE3, Chemical and Pharmaceutical 

 Industry Company, Inc., New York). The rectal probe was inserted 

 2 cm (Marcus et al., 1961b), 



Oxygen uptake studies were conducted by employing the Warburg 

 constant volume respirometer technique (Umbreit, Burris, and 

 Stauffer, 1957). The substrate was 2.5 ml of tryptose phosphate 

 broth. Standardized amounts of bacteria were added in a volume of 

 0.5 ml. The center well contained 0.2 ml of 20 per cent KOH plus 

 a 1 cm^ fluted filter paper. Flasks were set up in duplicate. 



RESULTS 



Effect of Varying Temperatures 



In order to assess the effects of acute and chronic low tempera- 

 ture stress on mechanisms of specific and nonspecific resistance to 

 microorganisms, it became apparent that information concerning 

 the behavior of the challenge agents at low temperatures was 

 necessary. It has been observed that certain small animals under- 

 go a considerable drop in core temperature when placed in an 

 environment in which the ambient temperature is considerably less 

 than the normal core temperature. Since specific information con- 

 cerning the metabolic and growth behavior of the challenge agents 

 (K. pneumoniae and S. aureus ) at temperatures lower than 37° C was 

 lacking, it became apparent that data were necessary for the in- 

 terpretation of experiments involving specific and nonspecific 

 resistance mechanisms at core temperatures less than normal. 



Growth of the bacteria was determined by employing turbidity 

 as a function of time. Turbidity of the growing cultures was 

 measured in a Klett- Summer son photoelectric colorimeter with a 

 blue filter. The numbers of organisms present for any given 

 turbidity measurement was determined from a standard curve 

 based on the assumption that each organism present divides at the 

 same time; the generation time for these experiments is defined 



158 



