CELL DIVISION, MORPHOLOGY, VIABILITY 



795 



t.ol ( °> 



4 0- 



20 



* 



* 



i 



i 



\ 



44 



88 



132 



176 



286 330 



MINUTES AFTER IRRADIATION 



Fig. 11-11. Per cent of Chortophaga neuroblasts in metaphase at different times after 

 32 r of X rays. These cells were kept at 38°C except for different intervals after 

 irradiation. The periods during which the cells were at 1°C are not included in the 

 graph. A, Control, B, 1°C from 57 to 132 minutes after X irradiation; C, 1°C from 1 

 to 66 minutes after X irradiation; D, 1°C from 1 to 220 minutes after X irradiation 

 (after Adams, unpublished). 



temperature after treatment on X-ray-induced changes in mitotic activity 

 in the grasshopper neuroblast. He found that exposure to 3°C for 220 

 minutes immediately after irradiation (32 r), followed by incubation at 

 38°C, delayed the fall to zero in the metaphase count and the subsequent 

 return of metaphases, as compared with cells kept at 38°C from treatment 

 on, by only slightly less than the time of the cold treatment (Fig. 11-11). 

 If the embryos were changed from 38 to 3°C at the beginning of the period 



