210 c 



MIYA, MARCUS AND PHELPS 



Temperature Treatment Mortality ratios at lU days 



(grouped) (single) 



8/10 



U/10 



20 C Zymosan 8/10 9/10 



9/10 

 1/10 



Table VI. Effect of acute cold (2° C) on mortality of mice challenged intraperi- 

 tJneally with 1 LD5q* of Staphylococcus aureus , strain Fritchie. Unacclimatized animals 

 immunized or treated andchallengedat room temperature, then placed at noted tempera- 

 tures. *1 LD5Q of S. aureus = 75 x 10^ organism per mouse as determined by method 

 of Litchfield and Wilcoxon (1949). 



vidually. The mortality ratios that were obtained under these 

 conditions are shown in Tables VI and VII. 



Table VI shows that mice challenged with 1 LDcq of S. aureus 

 are afforded protection when specifically immunized and kept in 

 groups of ten while acutely exposed to 2° C. However, mice caged 

 as individuals are not afforded the same degree of protection, 

 although resistance greater than that of normal mice is evident. 

 The nontreated acutely stressed control mice did not die when 

 grouped, and only 10 per cent (l/lO) died when caged singly. There- 

 fore, most of the deaths that occurred may be attributed primarily 

 to the challenge of organisms. Mice receiving zymosan or endotoxin 

 treatment prior to challenge did not fare as well as the specifically 

 immunized animals, and the significance of the difference in 

 mortality ratios between the normal and nonspecifically immunized 



174 



