298 



THE THEORY OF THE GENE 



abnormal offspring that show defects similar, in a gen- 

 eral way, to those induced directly in the original em- 

 bryos. 



How shall we interpret these experiments? Has the 

 radium first produced its effects on the brain of the de- 



5 



Fig. 156. 



Young mice embryos with hemorrhagic areas whose mother had 

 been treated with radium when the young were in utero. (After 

 Bagg.) 



veloping embryo, causing defects, and is it owing to the 

 presence of these defects that the germ-cells of the same 

 embryo become affected? There is an apparent objection 

 to this interpretation. We should expect when the brain 

 alone is affected, the next generation should show brain 

 defects ; when the eye is the principal organ affected, the 

 next generation should show only eye defects. So far as 



