EFFECTS OF IRRADIATION ON BEHAVIOR AND BLOOD 



699 



ABSOLUTE NEUTROPHIL 



8000 



63 DAYS 



Fig. 6. Neutrophils before and after irradiation. The preirradiation values in cells 

 per 100 ml of blood were: control group, 6,389; 300 r, 7,623; 400 r, 5,280; and 500 r, 

 6,751. 



the control group (1% level of confidence). This phase was followed by a 

 return to the normal range. 



The number of circulating neutrophils (Fig. 6) decreased on the 1st 

 irradiation day, the value undoubtedly representing the sum of a rise and a 

 fall shown by French and his co-workers (1955) to occur in the first 24 

 hours. The mean of the combined experimental groups was significantly 

 below that of the control group at the end of the 1st week and remained so 

 during the 2nd and 3rd postirradiation weeks. Recovery then commenced. 

 A differential rate of recover\' among the groups was apparent but was not 

 statistically significant. Again the most heavily irradiated group were fastest 

 in recovering, and the least irradiated group were slowest. By the 5th post- 

 irradiation week, a neutrophilia was apparent. The mean of the combined 

 irradiated groups was significantly above the control group at 5, 6, and 7 

 weeks after radiation. Values for the irradiated animals fell within the nor- 

 mal range during the 8th and 9th postirradiation weeks. 



Twenty-four hours after irradiation, the number of circulating lympho- 

 cytes had decreased, and the mean of each experimental group was signifi- 

 cantly lower than that for the control group (Fig. 7). The variance among 

 the means of the experimental groups was also significant. The findings at 

 3, 7, and 21 days after radiation were similar. At 14 days after radiation, 

 the variance among the means of the radiated groups was significant, but 



