342 



GENERAL DISCUSSION 



of the destruction of the latter. Tlie excital)ihty of the muscle progres- 

 sively falls — this is a "clear" period. 



3 4 



^ — ^—1 H 



20 40 60 80 kr 



2 



Fig. 1. — The variation of tlie dieletric losses in the tissues of mice in the process of 



irradiation with X-rays. 



The turning-point dose, after which the direction of the j^hysico- 

 chemical jjrocesses varies, is higher if the irradiated structure possesses 

 more highly differentiated biological properties which probably corres- 

 pond to a greater degree of macromolecular order. For example, the 

 fo^o^\•ing relationship is worth noticing: the stronger the electric 

 polarization at the boundary surfaces, the higher the "turning-point" 

 dose. For smooth muscle, the electric polarization at the interphases is 

 lower than for skeletal muscles, and correspondingly, for smooth muscle 

 the turning-point in the loss curve occurs at lower doses, (12 to 30 kr). 

 The impression is created that the degree of ion concentration at the 

 inter2)liases is indirectly connected with the factors which influence the 

 radio-resistance of the structure. 



On the basis of an analysis of the loss curves at various frequencies, 

 one may think that the mechanism of ion displacement in the structure 

 of the skeletal muscle in the "concealed" period lies in the amplification 

 of the ion concentration at the interphases. In connection with this it 

 is interesting to note that Alexander and Charlesby have observed a 

 phase of increase of the polymerization of synthetic polymers after 

 y-irradiation within a definite range of doses. 



We have also obtained a proof of the dependence of the radiation 

 effect upon the order of the structural construction of a muscle in experi- 

 ments with the irradiation of the denervated skeletal muscle of a frog. 

 A few days after cutting the nerve, the distribution of the electrical 

 charge in the muscle is altered on the side of a weakening of the ion 

 concentration at the polarized boundaries, and the reaction of the 



