172 



INACTIVATION OF COMPLEMENT BY LIGHT 



In Fig. 1 the results of this experiment are graphically presented 

 with the efficiencies of the different portions of complement plotted 

 as ordinates against their respective periods of exposure as abscissas. 

 The smoothed curves drawn between the points for any one temper- 

 ature allow us by interpolation to determine the exposure necessary 

 at that temperature to reduce the efficiency of complement by any 

 given amount. The rate of photoinactivation may be taken as 

 inversely proportional to the time required to reduce the hemolytic 

 power of complement to any selected per cent of efficiency. Calcu- 

 lation from such interpolated values of the average rate of inactivation 



TABLE I. 



The Efficiency of Samples of Complement Radiated at Diffierent Temperatures for 



Different Intervals. 



to 60, 40, and 20 per cent efficiency shows that if the velocity at 

 0°C. is taken as 1.00 the velocities at 10, 20, 30, and 40°C. are 1.02, 

 1.09, 1.25, and 1.47, respectively. Hence the temperature coefficients 

 for the four intervals studied are Qiq = 1.02, 1.07, 1.14, and 1.18. 

 These values are probably accurate to the second significant figure 

 only, so that although there appears to be a progressive increase in 



act upon the complement. These values are given in Table I. The heat efifect 

 is negligible at temperatures of 20°C. or below, so that ko = ki and no correc- 

 tion need be introduced at these temperatures. 



These experiments were done previous to the perfection of the method for 

 complement titration used for the remainder of the work described in this paper, 

 and, as might be expected, there are occasionally large inaccuracies. These are 

 obviously to be neglected in certain instances such as the 7 minute exposure at 

 0°C. 



