110 HOLLAENDER, StAPLETON AND BuRNETT 



cells, though in quantitatively different amounts. Read and Thoday 

 showed that both as regards gro\\'th inhibition and chromosome damage 

 in root meristems, anaerobiosis affords a roughly 3-fold protection 

 against X-radiation, exactlj^ in line with Dr. Hollaender's results, but 

 no appreciable protection against a-radiation. Mr. Boag and I recently 

 made some experiments with (D-D) neutrons which seem to show little 

 or no effect of anaerobiosis. It would therefore seem that the removal 

 of oxygen in these experiments affects the chemicals formed along the 

 track rather than the condition of the receptor molecules. Unfortunately 

 this isn't absolutely conclusive, because we also know that the chemical 

 effects produced along an alpha particle or a proton track are not 

 identical with those produced along an electron track. Perhaps Dr. 

 Hollaender might be able to say something about this aspect of the 

 problem. 



Hollaender: The experiments of Read and Thoday on the effects 

 of alpha particles and neutrons were repeated, using different organisms, 

 in our laboratory. We got practically the same results. Giles' work 

 (unpublished) with Tradescantia has shown that neutrons are inter- 

 mediate between alpha and X-rays; oxygen has slightly more effect on 

 neutron than on alpha ray damage, but not enough to be very im- 

 pressive. As yet we have no reportable results on chemical studies. 



Gordon: I was wondering whether 1,2-glycols have been tried for 

 protective action, in view of the fact that BAL, with two adjacent 

 mercapto groups, has a greater effect than cysteine. 



Hollaender: No, we haven't tried it. This is on our list. The 

 alcohols and the glycols are about one hundred times less protective 

 than BAL and cysteine. 



Gordon: Would the protection of a glycol be twice that of a mono- 

 hydric alcohol, or would it be greater than the molar proportions of 

 hydroxyl groups would indicate? 



Hollaender: As far as we know, propylene and triethylene glycol 

 are about as effective on the basis of molar concentration as the lower 

 alcohols. 



Holmes: Do you have any idea how much of these compounds, 

 particularly hydrosulphite, we can give to animals? If you can tell me a 

 safe dose to give a rat, I can try it on a nucleic synthesis during the next 

 week or two. I should like to see if it prevents the inhibition by X-rays 

 of nucleic formation. 



Hollaentder: About 12-5 mg. per mouse, given intraperitoneally 

 or intravenously. A dose of 25 mg. per mouse is toxic. 



Sloviter: Have you tried glucose? I have seen reports of hyper- 

 glycaemia giving protection against large doses of radiation. 



Hollaender: If E. coli is incubated in the presence of glucose, the 

 pattern of metabolism is changed and some protection is obtained. If 

 bacteria are grown anaerobically in the presence of glucose, they become 

 very resistant, as we have shown. Stapleton, in our laboratory, has 

 worked out the resistance in aerobically grown organisms throughout 

 the groA\'th cycle. They become very resistant just before they come 

 out of the lag phase; then their sensitivity increases when they go into 



