638 BIOLOGICAL EFFECTS OF RADIATION 



concordant with these. From such experiments, of course, no conclusions 

 relevant to the permeabiUty of the cell membrane can be drawn. 



Gassul (116) irradiated (2 to 3 H.E.D.) explants of frog spleen in 

 carmine-containing plasma. The reticular cells and, with stronger doses, 

 the endothelial cells acquired a fine granular stain, although the controls 

 took up no dye. The softer rays (those stopped by 3 mm. of Al plus 

 0.5 mm. of Zn) were the most effective in causing increased penetration or 

 accumulation of the dye. 



C. Hoffmann (153) studied the effects of roentgen rays of varying 

 hardness upon the penetration of trypan blue, light green, methyl red, 

 and neutral red into Opalina ranarum in culture. Doses of 500 and 

 1000 r were used. Irradiated cells accumulated stain more rapidly than 

 control animals; hard and soft rays had the same effect. 



In the experiments of Schmidt (331), Halberstadter and Wolfsberg 

 (128, 129), Holtermann (157), and Tsebrikow (368) dyes are injected 

 into whole irradiated animals, and there is determined the accumulation 

 of these dyes in special tissues, particularly kidney epithelium. These 

 results should not alone be considered as evidence for a change of tissue 

 cell permeability after roentgen irradiation; if they imply a membrane 

 effect at all, it is an increase, never a decrease, in permeability. 



A number of workers have used electrical methods, which have the 

 advantage of physical precision, but probably insuperable biological 

 disadvantages — to use a change of electrical conductance or polarization 

 resistance as a measure of permeability change, one must make a great 

 number of simplifying assumptions, particularly about the state of the 

 intercellular material and the concentration of free electrolyte within the 

 cell. Thus the formula of Philippson, used by the two authors about to be 

 considered, treats the tissue as a resistance and a capacity in series, with 

 a shunt, and assumes that all cell membranes are lipoid in nature. 



Mendeleef (259) irradiated guinea pigs with doses of 720 r 

 (4 ma., 188 kv., 0.5 Cu + 1.0 Al) and determined the electrical constants 

 of liver tissue by the method of Philippson. The calculated results show 

 a decrease in the ohmic and polarization resistance of the membranes 

 which is interpreted as indicating increased cell permeability to ions. 

 Tsebrikow (367, 368) used the same method with tissues of irradiated 

 normal and cancerous mice. Her doses were 100 and 600 r and she tried 

 rays of varying hardness. In all cases irradiation of the animal caused 

 an increase in tissue permeability, 40 per cent in normal tissue, 50 to 60 

 per cent in tumor tissue. 



This latter result contradicts the conclusion of Waterman (382) that 

 tumor cells and normal cells are affected by roentgen rays in an opposite 

 manner. Waterman, however, compared rather acidic suspensions of 

 isolated tumor cells with suspensions of lymphocytes. The ratio 

 of the polarization resistance to the ohmic resistance (Waterman's 



