IRRADIATION OF LIVING PROTOPLASM 637 



The relative permeability effects of the different products of radio- 

 active disintegration cannot be determined from the sparse data available. 

 It seems true, at least, that alpha rays and mixed beta and gamma rays 

 may cause an increase in cell permeability; as for gamma rays, we have 

 only the contradiction between the experiments of Packard and of Van 

 Herwerden. 



ROENTGEN RAYS 



It is consonant with the therapeutic importance of the roentgen 

 rays that their general cellular effect should long have been the object 

 of thought and some research. As the physiological importance of 

 membrane changes has become recognized, attention has been turned to 

 the effects of roentgen rays on cell and tissue permeability. The litera- 

 ture is not large, but the several workers are in good agreement. There 

 is as yet no single investigation that can be considered quantitatively 

 valid both physiologically and radiologically. 



The first direct consideration of the problem is that of Richards (314) 

 who used four of the criteria of permeability increase then current: (a) 

 pigment release from Arenicola larvae, (b) penetration of alkali into 

 cells stained with neutral red, (c) penetration of neutral red into cells made 

 alkaline, and id) artificial parthenogenesis. Richards does not describe 

 his source of radiation, but all of his results are negative. Irradiation 

 caused no release of pigment from Arenicola larvae, nor did it change the 

 "permeability" of the eggs of Asterias or Arhacia, nor did it activate 

 them. 



Brummer (48) treated human skin with a dose of 10 X-units (at 2 ma.) 

 and determined permeability to NH4OH after the method of Gans and 

 Schlossmann already described. The stained skin was decolorized in 

 8 min., while the control required 6 hr. Softer rays (5.3 ma.) proved 

 more effective, although the extent of the difference is not clear. The 

 same author (49) attempted to extend his conclusions to erythrocytes. 

 Cells exposed to 3, 6, 10, and 15 X-units were suspended in methylene 

 blue, centrifuged after a period of time, and the intensity of the super- 

 natant dye determined. As the dose increased, the amount of dye 

 taken up by the cells diminished, indicating a permeability decrease, 

 in contradiction to Brummer's results with skin. 



Kovacs (198) used the fact that methyl violet must attain a certain 

 concentration in the frog heart before it stops the beat, to estimate 

 permeabihty changes in the cardiac tissue. The heart received 6 H.E.D. 

 and was immersed in dye solution. Beating stopped in 20.5 min., 

 although the control required 28 min. This difference is not striking, 

 but experiments in which time of immersion was kept constant and the 

 intensity of dye in the heart measured with a colorimeter gave results 



