134 Drs. H. Chambers and S. Russ. Action of [May 1, 



of the serum added, and therefore to the amount of complement present, 

 as may be seen from fig. 7. For hsemometer readings below 20 accuracy is 

 not claimed. 



Fig. 7. 



The volume of serum exposed to the radiation in the opsonin experiments 

 was 12 - 5 cu. mm., but this being an inconveniently small quantity in the 

 complement estimations, the volume was increased to 30'5 cu. mm. After an 

 exposure of any desired interval the amount of complement in the radiated 

 serum was compared with that in the control. The results may be seen 

 from Table V and fig. 8. 



Table V. 



Time of exposure. 



Percentage of complement 

 remaining. 







13 15 



92 



17 30 



82 -5 



22 15 



76 -6 



28 



86 



36 25 



64 



41 15 



48 



44 35 



46 -8 



46 30 



52 -9 



54 15 



15 estimated 



66 30 



10 



A*'comparison between this curve and that in fig. 6 shows a striking 

 dissimilarity in the reductions of opsonin and of complement in serum when 

 subject to a-radiation; but the two curves are not quantitatively com- 

 parable, owing to the difference in the volume of serum radiated in the two 

 cases. For this reason three determinations of the reduction in opsonin 



