250 HILDEMANN, LINSCOTT AND MORLINO 



ing the body weight or relative organ weight per lOO grams body- 

 weight over the mean of the respective weights of two httermate 

 controls. Thus indices greater than i indicate organ enlargement, 

 while indices less than i indicate a body or organ weight less than 

 that of the control animals. Statistically significant differences are 

 evidenced by individual indices more than two standard deviations 

 from i; likewise, a mean index value more than two standard 

 errors from i may also be regarded as significant. 



Three animals showed no gross pathological changes at autopsy. 

 The weight indices of these mice similarly indicated no signifi- 

 cant deviation from the normal. The remaining nine animals all 

 revealed pathological changes, most consistently in the hver as 

 evidenced by anaemia and/ or focal necrosis. However, grossly 

 normal lymph nodes were observed in all animals. High Hver 

 indices (enlargement) were closely associated with severe runting 

 (low body weight indices) and conspicuous pathological changes. 

 Significant kidney enlargement occurred only in conjunction with 

 severe runting, which suggests that kidney failure is involved in 

 the latter stages of the fatal disease. Although the body weight 

 indices of all 12 animals were less than i, only five individual 

 indices were significantly depressed. Nevertheless, the mean 

 indices for both 14 and 15-day groups were significantly low. 

 Inspection of the hver and kidney indices similarly revealed 

 significant organ enlargement which was, however, much greater 

 for the hver. Although marked splenomegaly was also observed, 

 atrophy of this organ was pronounced in animal No. 12, which 

 was nearly moribund at the time of assay. For this reason, only 

 one of the two mean spleen indices is significantly high. Heart 

 weight indices were also determined and none differed substan- 

 tially from the normal. It may be noted that liver and spleen 

 indices were high in two animals (Nos. 2 and 4) that showed only 

 slight body weight depression, whereas the reverse situation 

 obtained with animals 7 and 8. From an overall quantitative 

 standpoint, the mean body weight and hver indices most sensi- 



