640 BIOLOGICAL EFFECTS OF RADIATION 



Koch (191) gave the blood of human patients 600 r m vitro. Permea- 

 bihty changes were estimated by the hematocrit method and by chloride 

 analysis. In most of the cases the results showed a permeability increase. 



Saxe (322) measured the permeability to water of pig bladder upon 

 irradiation with 3000 r. The bladder was stretched across the mouth 

 of a simple osmometer. He obtained, in the one experiment men- 

 tioned, a considerable increase over the control in the rate of water pene- 

 tration, but later work does not seem to confirm these results (122). 



For plant cells there are data obtained by Williams (391) on her prepa- 

 rations of cells of Saxifraga umbrosa. Her method and the trend of her 

 results are the same as in her radium experiments already considered. 

 Roentgen rays caused increased permeability certainly to water and 

 probably to other substances. As early as 1902 Seckt (340) had observed 

 stomatal closure in cells of Tradescantia selloi under roentgen irradiation, 

 which, by the criterion of Williams, is evidence of permeability increase. 



On the whole, in spite of conflicting results, we should be inclined 

 to believe that all types of radiation which affect living cells do cause a 

 definite increase in the permeability of the plasma membrane. Never- 

 theless, in spite of the large number of papers already published, it is 

 desirable that much more work be done in this field. The best methods 

 have scarcely been used at ail, and there is a dearth of certain and accu- 

 rate information. 



SURFACE CHARGE 



Many writers have proposed changes in the electrical charges of proto- 

 plasmic colloids as the principal cause of the biological action of radi- 

 ations (33, 63, 233, 235, 262, 400, etc.). There is very httle experimental 

 evidence bearing on this view, which seems a reasonable inference from 

 the well-known ionizing effect of all radiations. It must be pointed out 

 that there is relatively little information of any sort concerning electrical 

 charges either of cell surfaces or the surfaces of the cytoplasmic granules. 



Young and Pingree (396) detected a retardation of the electrophoretic 

 movement of cells of Sarcina flava, Sarcina rosea, and Bacillus prodigiosus 

 suspended in glucose when the cells were exposed to the light of an 

 incandescent bulb. Their results are not strictly quantitative, as the 

 unequal distribution of the light through the circular cross section of the 

 U-tubes used resulted in the formation of irregular migration surfaces. 



A similar decrease in the negative charge of bacteria is reported by 

 Lisse and Tittsler (239). These authors measured by the method of 

 Falk the velocity of anodal migration of Escherichia coli suspended in 

 water. Exposure to a 500-watt Mazda bulb caused a brief increase 

 followed by a steady decrease in the rate of movement of the cells in the 

 electrical field. 



The effect of ultra-violet irradiation on the zeta potential of erythro- 

 cytes was measured by Falk and Reed (93). They irradiated dog blood 



