1042 



RADIATION BIOLOGY 



This work, which was performed on rats, indicated that the pattern of 

 hematologic effects was qualitatively similar to that produced by X 

 radiation. The observations of Lawrence have been extended to other 

 laboratory animals, including mice and rabbits (Lawrence, Aebersold, and 

 Lawrence, 1936; Henshaw et al., 1946; Jacobson and Marks, 1947). 

 Uranium-pile fast neutrons have been explored and compared with 

 cyclotron-produced fast neutrons (Zirkle, 1947). Henshaw exposed mice 

 to single doses of 26, 50, 78, 90, or 105 n. These studies paralleled 



1 0,000 



Fig. 16-8. Effect of single doses of fast neutrons on the heterophil values of the periph- 

 eral blood of rabbits. 



studies on rabbits exposed to cyclotron fast neutrons, in which dosages of 

 9, 26, 55, 68, 76, 89, 97, 106, or 128 n were used. No difference in the 

 hematologic effect of the LD 5 o dose of cyclotron or pile fast neutrons 

 appears to exist. 



Figures 16-8, 16-9 show the effect of cyclotron fast neutrons on the 

 leukocyte values of rabbits, and Table 16-1 gives the comparative effect of 

 X rays and fast neutrons on the lymphocyte response in rabbits. 



An initial increase in heterophils follows exposure to fast-neutron 

 dosages of 9-128 n, and within the first 24 hours there is also an initial 

 rise. This is followed, after dosages ranging from 26-128 n, by a reduc- 

 tion, reaching a minimum in 3-5 days. No significant reduction in 

 heterophils occurs after an exposure to 9 n. Eventual recovery to 



