Radiation Dose in Autoradiography 137 



of individual cells, and I think we may look for great advances to follow 

 upon the application of this method in radiobiology. 



Hollaender: Isn't 2-5 roentgens sufficient to upset the rate of 

 mitosis? 



Gray: In exceptionally sensitive tissues, such as grasshopper 

 embryos, it is, but it would not appreciably interfere with the growth 

 of plant meristem or cause chromosome damage in more than one or 

 two out of every 100 cells. 



Holmes: If 2-5 roentgens were delivered to a whole animal the 

 radiation effects might not be negligible. If you were interested in the 

 blood forming organs, the dose of 2-5 roentgens to the whole body due 

 to the 3 2p incorporated into the tissues might not be without effect on 

 the biological change which you were studying. 



