346 



BIOLOGICAL EFFECTS OF RADIATION 



where fc is a constant, t is time, a is the original amount of photolabile sub- 

 stance, and X the amount destroyed in time t. For cyclamin, k = 0.0033 

 when t is expressed in minutes and Briggsian logarithms are substituted 

 for natural logarithms. The goodness of fit of the observed to the 

 theoretical curve may be judged from Fig. 1. The agreement seems 

 satisfactory and this research constitutes one of the pioneer demon- 

 strations of the conformity of biological reactions to classical physico- 

 chemical laws. 

 





10 20 30 40 50 60. _ 120 180 



Time in Minu+es 

 Fig. 1. — The relative hemolytic activity of cyclamin after different periods of irradia- 

 tion. The straight line is the theoretical curve for k = 0.0033, and the points represent 

 observed values. Ordinates represent logarithms of a-x (the fractional part of the original 

 activity); abscissas, time in minutes. (After Dreyer and Hanssen, 46.) 



Seyderhelm and Opitz (148) subjected purified saponin to ultra- 

 violet radiation from a quartz-mercury-arc lamp, and found that it 

 rapidly lost both its hemolytic power and its power to so injure leucocytes 

 as to make them take up (become permeable to?) Congo red and trypan 

 blue. The authors attribute the inactivation to decreased dispersion, as 

 shown by the appearance of the Tyndall phenomenon after 5 to 6 hr., 

 and of gelation after 7 hr. irradiation. There was also a decrease in the 

 surface tension of the solution. Further changes in the physiological 

 activity of saponin upon irradiation are also recorded, and Wheeler-Hill 

 (164) in the discussion appended to the paper of Seyderhelm and Opitz 

 (148), contributes some new data including studies on the absorption 

 of light of X < 3340 A. This increases during irradiation. 



Tappeiner and Jodlbauer (156) reported that ricin, the toxic protein of 

 Ricinus, lost its agglutinating power when exposed to sunlight in the 

 presence of oxygen and such photodynamic sensitizers as eosin, fluores- 

 cein, etc. Crotin, from Croton sp., resembled ricin. 



Busck (31) investigated in detail the protective effects of normal 

 serum or other protein colloids added to ricin-dye mixtures which were 

 then exposed to visible light. The agglutinating power of the ricin 



