SUSCEPTIBILITY OF AMPHIBIAN OVA TO X-RAYS 



435 



4. Larvas markedly abnormal very early In development 

 (figs. 12—13). 



5. Abnormalities in larvae become well marked as the period 

 for hatching approaches (figs. 14, 15 and 16). 



6. Failure of larvae after hatching to grow normally into 

 active healthy tadpoles. 



7. Failm-e of normal metamorphosis. 



In the following subsections this classification will be used in 

 studying results of exposure at different stages of development. 



1. EFFECTS OF EXPOSURE OF SPERMATOZOA TO THE X-RAYS 



The following table gives a summary of the more successful 

 experiments made to test the effects of exposure of the sperm of 

 the toad and frog to the X rays. The details of the effects of this 

 exposure on fertilization, cleavage, gastrulation, embryonic 

 differentiation and subsequent development are discussed in 

 the paragraphs which follow the table. 



TABLE 1 

 Experiments on X-ray exposure of sperm 



Figures in brackets indicate percentage of eggs discarded because of lack of 

 fertilization. 



THE AMERICAN JOURNAL OF ANATOMY, VOL. 11, NO. 4 



