284 G. M. FRANK AND A. D. SNEZHKO 



of this regulation mechanism by studying kinetic phenomena — the 

 rhythm of oxygen ntihzation and the rhythm of submicroscopical 

 motility. 



REFERENCES 



Aladjalova, N. a. (1956). Biophysics (Russ.) 1, 2. 



Davies, p. W., and Brink, F. (1942). Rev. sci. Instrnm. 13, 'rli. 



Frank:, G. M. (19o8a). Bull. Acad. Sci. U.R.S.S. (Biol.) 1, 23. 



Frank, G. M. (1958b). J. Acad. Sci. U.S.S.R. No. 3. 



Frank, G. M. (1960). "Fiziko-chimitclieskije i strukturnye osnovy biologicheskih 



yavlenii." Izdatelstvo Akad. Xauk. U.S.S.R., Moscow. 

 Snezhko, a. D. (1956). Biophysics (Russ.) 1, 6. 

 SNEZHgo, A. D. (1957). Biophysics {Russ.) 2, 1. 



DISCUSSION 



MANOiLOV : Does the rhythmicity which you have so well shown, occui* through- 

 out the radiation siclaiess or only during the first hours? Did you observe such 

 rhythmical changes in other tissues of the living organism? 



FRANK : Today I have only spoken about the first hours, but this change of the 

 free oxygen balance occurs throughout the long period of the reaction in the 

 irradiated organism. But, at later stages, these changes are of a secondaiy nature. 

 Similar changes of the relationship were observed on very different objects. 

 Today I have demonstrated as examples only plant material and yeast. 



SHABADASH: The rate of oxygen utilization depends on the enzymatic activity of 

 mitochondria. You know, that in our laboratory it has been shown that within 

 a few minutes of irradiation cytochemical changes occur in the nerve cell mito- 

 chondria of the brain cortex. WTiat data can you give on electron microscopic 

 changes of the mitochondria, which parallel the changes in oxygen vitilization? 



FRANK: Because of time limitations I was not able to dwell either on your woi"k 

 or on the very interesting work of Noed, who has .shown that practically immedi- 

 ately after the irradiation the number of mitochondria, determined in liver mito- 

 chondria fraction, rapidly decreases. It is remarkable that this process is reversible, 

 the numbers later returning to normal. The number of mitochondria is restored 

 within about 5 to 6 hours, showing good correlation with the time course of the 

 oxygen utilization disturbances which I have demonstrated here. 



BACQ: In the experiments in which oxygen tension was studied in living tissues 

 the tip of the electrode was in contact with the cell, but was not within the cell. 

 What was the position of the electrode when you worked with the yeast cells? 



FRANK : In case of yeast the electrode was immersed in a drop of the yeast cultiu-e. 



ZELISCHEV : It is remarkable that when a leaf is irradiated, there was no local 

 effect as was observed with all other objects. If it is an extraordinary exception 

 from the general rule, very interesting consequences may follow. Please, explain 

 in detail your views on this matter. 



FRANK : The effect was also local but in this case, as is often the case with other 



