THE RHYTHM OF OXIDATIVE PROCESSES 275 



diffusion current both in the cortex and subcortex was found (Fig. 3.). 

 This i)roves a deterioration of the abihty to utihze oxygen, ('ontrol 

 electrodes showed eitlier no changes or the changes were much smaller 

 and, which is most important, those which arose did so with a con- 

 siderable delay. The latter fact shows that the given attenuated effect 

 arose at a distance of some millimeters not at the expense of radiation 

 dispersion in tissues but as a peculiar "diffuse" distribution of the in- 

 hibition of oxidative processes on account of specific substances formed 

 at the site of treatment. This is confirmed by the fact that a decrease 

 in the dose of irradiation to 100 r, when the "oxygen test" no more 

 gives statistically trustworthy results, leads only to a diminution of the 

 amplitude of this effect without causing a delay in time. 



Thus we see this method a possibility of directly identifying 

 primary cellular responses to radiation under in vivo conditions in a 

 complex organism. 



One more interesting phenomenon turned out to be related to these 

 apparently local and primarily-arising responses to radiation. 



A thorough analysis of the regularities of the behaviour of free 

 oxygen in tissues showed its level to be far from stable in normal con- 

 ditions. Actually in all cases a variation in this level is observed, i.e. a 

 rhythm of oxygen content in the tissues. These rhythmical changes are 

 mostly of two orders. A rhythm of a smaller amplitude and a higher 

 frequency, 15 to 20 per min, and a rhythm of a greater amplitude 

 with a frequency of 2 to 3 per min. Very often both rhythms existed 

 simultaneously (Fig. 4.). 



This rhythmical free oxygen level turned out to be functionally re- 

 lated to the state of the central nervous system. So, oxygen rhythm is 

 probably eliminated upon experimental development of the inhibition 



'^VVA^^VV\AV%A/V^'V\A^iAAAA'VVVVNA(VV\ 



yOlflA 



Tl 



01 



lvv/W%yvAv 



Imin 

 Fig. 4. — Forms of rhythm of oxygen tension in the brain. 



1, rhythm with the frequency 15 to 20 per min; 



2, rhythm with the frequency 2 per min ; 



3, Tlie first and second forms of rhythm combined. 



