1911.] Radium Radiations upon Normal Blood. 133 



o 16 3d 35 ~ub ~3o 

 JJoustt. 

 Fig. 6. 



opsonin is not strictly quantitative, it cannot be asserted that the destruction 

 of opsonin rigorously follows an exponential law. 



The Action of the Radiations on Complement. 

 A similar series of observations was made with heemolytic complement. 

 For this purpose a thin film of serum was exposed to the a-radiation 

 from one of the capsules in the manner already described. The comple- 

 ment in the radiated serum was then compared with that contained in the 

 control. 



In order to obtain a quantitative estimate of the complement, a method 

 similar to that described by Dr. Emery* has been used. 



Briefly, the method consists in procuring a 20-per-cent. suspension of 

 fully sensitized red blood corpuscles, obtained by adding to 1 volume of 

 washed corpuscles, 4 volumes of a strong immune serum. To 4 volumes 

 of this suspension is added 1 volume of the serum, the complement in 

 which is being tested. After being kept at 37° C. till haemolysis is com- 

 plete, the liquid is centrifugalised and the amount of free haemoglobin 

 in a constant volume (76 cu. mm.) of the supernatant fluid tested by means of 

 a Sahli hamioraeter. 



This instrument was calibrated by adding to 4 volumes of sensitized red 

 corpuscles 1 volume of serum of varying dilutions. The amount of free 

 haemoglobin as read from the scale of the instrument was found, within 

 the limits of the experimental error, to be proportional to the strength 

 * Emery, 'Lancet,' 1911, p. 490. 



