442 



BIOLOGICAL EFFECTS OF RADIATION 





Fig. 16. — Effects of X-rays upon regeneration and cells of Amblystoma larvae. A, 

 longitudinal section through a limb stump of a nonirradiated control 18 hours after amputa- 

 tion showing healing and beginning of normal changes in the cartilage of humerus; B, the 

 same 4 days after amputation showing further normal changes in cartilage and beginning of 

 blastema; C, the same 9 days after amputation showing further changes as above; D, the 

 same at 12 days; E, longitudinal section through limb stump of an irradiated larva 11 hr. 

 after amputation showing healing as in control; F, the same 4 days after amputation 

 showing absence of the typical blastema; G, the same 8 days after amputation showing 

 absence of typical blastema and degeneration of cartilage of humerus; H, the same 13 days 

 after amputation (c/. with D above) showing further reduction of humerus. {From Butler, 

 7.) 



