30 



NEUTRON EFFECTS ON ANIMALS 



groups, that the blood hemoglobin level was decreasing in those animals 

 surviving for more than one week, some blood hemoglobin determinations 

 were made. From these data it was found that the animals dying after 

 the first week showed a progressive decrease in blood hemoglobin to below 

 7 g. per cent, just prior to death. The important data, involving only- 

 changes in body weight and total leukocyte counts, have been graphically 

 summarized in Fig. 1. 



GRAMS 



250 



230 



210 



190 



170 



150 



CONTROLS 



120 N 



\ ISO AND 240 t 



10 



20 



25 



15 



DAYS 



Fig. la. Changos in body weight from the day of the initial neutron dose for rats 

 receiving 17.5 n to 240 n. Deaths during the course of the experiment are indicated 

 bv arrows. 



At neutron doses of 17.5 n to 47.5 n, some loss in weight occurred, but 

 since it was practically the same at all three levels of radiation, these data 

 were averaged before being plotted in Fig. 1. At no time did any of the 

 rats at this level of radiation show any signs of being ill. On autopsy, 

 when the experiment was terminated, some atrophy of the thj^mus and 

 testes was the only significant gross finding. 



Two groups of rats receiving practically identical doses of 60 n and 62.5 n, 

 respectively, showed quite different results. Three of the six rats receiving 



