NEUTRON EFFECTS ON ANIMALS 



G3 



laterals were considered. In the control group, 5 per cent of the plants 

 had lateral roots, while 42 per cent of the irradiated group hadreached this 

 stage of development. This work must be repeated with special precaution 

 to make certain that the appearance of stimulation was not the result of 

 some unknown factor interfering with the lateral roots of the controls. 



Comparison of the Ejfccls of P^ast and Lower Energy Neutrons. When 

 equal doses (according t(^ measurement 1)>' the 100 r chamber) of the two 

 (lualities of neutrons were used, the primary roots subjected to the lower 



A B C 



Fig. 3. Effects of two qualities of neutrons on root development of corn. A = 

 Controls. B = Radiated with 400 n (fast neutrons). C = Radiated with 400 n 

 (lower energy neutrons). 



energy neutrons were more damaged.than those subjected to fast neutrons 

 within the range 200 to 2000 n (Fig. 2). When the time of appearance of 

 the lateral roots of the two groups was compared, a dose as low as 100 n 

 showed a difference between the two (jualities of neutrons. When counts 

 were made of ])oth groups, 98 hoiu's after germination, 70 per cent of the 

 seedlings of the fast neutron group had laterals, while only 46 per cent of 

 the lower energy group had them. When the two 4()0-n gi'oups were 

 examined 82 hours after germination, 32 per cent of the fast neutron group 

 had laterals, while none was present in the others. The photograph 



