634 BIOLOGICAL EFFECTS OF RADIATION 



permeability increase in the membrane of Strongylocetitrotus (sea urchin) 

 eggs. After irradiation at a point on the surface of an egg, he placed the 

 egg in hypotonic or hypertonic sea water. In hypotonic sea water he 

 observed a protuberance, in hypertonic an invagination of the surface at 

 the point irradiated, indicating more rapid movement of water across the 

 membrane at this point. Tschachotin further reported that decoloration 

 of neutral red-stained eggs exposed to alkali occurred most rapidly at the 

 point irradiated. 



Besides these experiments, most of the information concerning the 

 action of ultra-violet on permeability concerns specialized tissues. Eck- 

 stein and von MoUendorf (87) studied the accumulation of trypan blue 

 in the kidney epithelium of irradiated and subsequently injected rats. 

 The dye accumulated more readily in the cells of the irradiated animals 

 than in those of the controls. This type of result has been quoted 

 {e.g., by Tsebrikow, 367) as evidence for a permeability change. Cer- 

 tainly it is too indirect to be of much value ; the authors themselves do 

 not consider permeability. 



Gans and Schlossmann (110) applied the indicator method to the 

 investigation of the penetration of NH4OH into sections of human skin. 

 The skin, stained with neutral red, was obtained from patients irradiated 

 with direct sunlight or a mercury-vapor lamp. Four cases are given, and 

 in each the decoloration of the rayed section proceeded faster than that 

 in sections of nonirradiated skin from the same patients. 



They quote as further evidence for their view the data of Regelsberger 

 (309) who measured the polarization resistance of normal and irradiated 

 skin. His source of ultra-violet was of sufficient intensity to cause 

 erythema 2 hr. after a 1-min. exposure. At the onset of erythema 

 Regelsberger observed a 10- to 200-fold increase in the polarization 

 resistance, which Gans and Schlossmann consider a measure of per- 

 meability. Keller (184) obtained similar results. It is obvious that in 

 all of these experiments a tissue of many layers is being considered, so 

 that cytolytic changes, rather than reversible membrane effects, may 

 be responsible for the electrical fluctuations. This criticism is vigorously 

 advanced by Lewis and Zotterman (227). 



RADIUM 



The investigation by Maud Williams (392) of the effects of combined 

 beta and gamma rays on epithelial cells from the petiole of Saxifraga 

 umbrosa includes estimations of permeability changes (a) by measure- 

 ments of the stomatal apertures, following a theory of stomatal closure 

 similar to that of Kisselew, according to which closure is caused by 

 permeability increase; and (6) by determinations of the rate of plasmolyis 

 by sugar solutions. Her sources were 0.1 gm. of radium element and 



