FLUORESCENCE STUDIES OF NUCLEOPROTEINS 120 



earrieil out to<;etlier witli you tliis jiossihility was evidently not confirmed. The 

 spectrum of the orangt^ Uuninescence of (he acri(hne orange adsorbed to bio- 

 logical substrate is identical with that of a very concentrated water solution, 

 while the spectrum of the green fluorescence coincifles with that of the diluted 

 water solution of this stain. There is at present also no indietion of the change of 

 the duration of the excited states. 



Thus the physical mechanisui of the observed changes consists probably in a 

 greater or lesser proximity between the adsorbed stain molecules, i.e. a greater 

 or lesser degree of interaction between molecules of the stain adsorbed by the 

 biological substrates, and a greater or lesser amount of the stain. 



gray: In relating the changes to the time, should it not be measured starting 

 from the begirming not from the end of the exposure. What was the irradiation 

 dose -rate in yovir experiments? 



MEissEL: In the case of the total body irradiation the dose-rate was about 74 to 

 75 r/min, i.e. all tlie dose was administered to the animal during about 15 minutes. 

 When tissue cultures were irradiated it was possible to use irradiation of a 

 very high dose-rate of the order of 20,000 to 25,000 r per njinute. 



