SUSCEPTIBILITY OF AMPHIBIAN OVA TO X-RAYS 



465 



but this is probably due to an individual difference in susceptibility 

 in the two lots of eggs. In Experiment C-2 but 1.6 per cent 

 developed into free swimming tadpoles and these died within 

 ten days after fertilization of the ova.^ 



TABLE 5a 

 Irradiation during cleavage 



^In experiments C-l| and C-2 mould and degeneration made it impossible to subdi- 

 vide the specimens which did not develop intolarvse. Most of these, however, were 

 probably unfertilized eggs. In Experiment D-lj, 8.9 per cent of the total number 

 of eggs were apparently not fertilized. The lack of development in these eggs is 

 not, however, to be attributed to exposure to the rays, since 9 per cent of the con- 

 trol eggs were not fertilized. 



