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



related to oxygen utilization. Varions parts of the central nervons sys- 

 tem were fonnd to behave in an individual manner. 



The first thing noticed when the experimental animal was irradiated 

 either totally or locally to its head, was a picture just the opposite of 

 the exjDected one. Despite a profound disturbance of the haemody- 

 namics which began in the first hours after total irradiation, no 

 imi^overishment of the brain tissue in pure oxygen was found. This 

 could be convincingly demonstrated with the use of the "oxygen test" 

 which showed a distinct decrease in the ability of the tissue to utilize 

 an extra supply of oxygen (Fig. 1). 



Fig. 1. — Change At in the resuh of X-ray irradiation. 



1, before irradiation; 3, 5 hr after irradiation; 



2, 1 hr after irradiation; 4, 7 hr after irradiation. 



Thus, this approach to the investigation shifted the centre of atten- 

 tion from the observation of the after-effects of haemodynamic dis- 

 turbances, as was expected earlier, to the observation of disturbances 

 in tissue resi:>iration. 



It is evident that this method has important advantages over two 

 procedures widely applied until recently, namely the study of gas 

 exchange, which gives vital but only integi'al values for the organism 

 as a whole, and the study of tissue respiration on tissue homogenates 

 and tissue sections. 



The literature 23ertaining to this question is referred to in detail in 

 Snezhko's papers. It should be pointed out that when investigating 

 total gas exchange somewhat contradictory data are obtained which 

 are evidently associated with the conditions of treatment, the time of 

 observation and the individual behaviotn- of various animal tissues. 



