83 



Chargaff very much. 



CHARGAFF: I don't bother easily. I really don't know. I seem to 

 gather that the theory now is that DNA makes RNA and RNA makes protein. 

 This may be so in special cases. I think there is some evidence that DNA makes 

 DNA and RNA makes RNA. In fact, there is little chemical relationship at least 

 between the total DNA of the cell and the RNA. We have looked for this but there 

 does not seem to be any. 



PATT: On the basis of UV absorption, Mitchell believed that RNA in- 

 creased and DNA decreased after X irradiation. He thought that there was a 

 block in the conversion of RNA to DNA. 



TOBIAS: I do not believe that Mitchell's experiments and our model 

 necessarily contradict. Some of the RNA may be inactivated, but still physically 

 present; the cell is then compelled to make new, active RNA, thus the total cell- 

 ular RNA is actually increased after exposure to radiation. 



