SPECIFIC AND NONSPECIFIC RESISTANCE 



Inoculation Hortality Ratios 



Route Dose 2* C 21® C 



S. C* 10** 



io5 



5 X 105 

 I. P.** 10 



100 

 1000 



Table XVIII. Mortality ratio of acclimatized mice kept at 2"^ C and inoculated with 

 Ehrlich Ascites tumor cells. ♦Subcutaneous Challenge. •♦Intraperitoneal Challenge. 

 ♦♦♦Dead/Total. 



Ehrlich ascites tumor cells were kept in a stock suspension and 

 occasionally were passed intraperitoneally into mice. The tumor 

 cells were harvested and washed three times with Hank's balanced 

 salt solution (BSS). The cells were suspended in Hank's BSS, and 

 viable cells were counted in the hemocytometer using a .0 5 per 

 cent solution of eosin as diluent. Stained cells were considered non- 

 viable. The cells were then diluted to the desired concentration in 

 the same medium. 



Subcutaneous challenge . The challenge inocula were prepared as 

 described and adjusted to contain 10^, 10^, and 5 x 10^ tumor cells 

 per 0,5 ml. The cells were injected into the nuchal region. The ex- 

 periment was terminated 90 days after inoculation of the cells. Low 

 ambient temperatures as shown in Table XVIII did not significantly 

 affect the final mortality ratios, regardless of the inoculum size. 

 However, when animal mortality is plotted as a function of time, a 

 significant delay in mortality is seen (Fig, 13), The effect is most 

 pronounced in the highest challenge doses while a graded diminished 

 effect is evident in the lower doses. 



Intraperitoneal challenge . The challenge inocula were prepared as 

 described and adjusted to contain 10, 100, and 1000 tumor cells per 

 0,5 ml. The acclimatized mice were challenged intraperitoneally, 



189 



