54 



PROPEBTIES OF ELEMOLYTIC SERA 



far from being the case. In other experiments we have 

 found, when lysis is produced first, then a small quantity 

 of Cd added and allowed to combine, and then increasing 

 amounts of C, that the surplus C appears to come off less 

 sharply than when C alone has been added. This would 

 appear to indicate that a certain amount of Cd is displaced 

 by C ; it must, however, be a small amount. 



We may therefore conclude that the C and Cd have 

 approximately the same combining affinity for the R + IB 

 molecules after lysis. If there is a difference in favour 

 of the energy of combination of the former, it is a slight one. 



ON THE RELATIVE FIRMNESS OF UNION OF COMPLEMENT AND 



COMPLEMENTOID WITH A SERUM -f- ITS ANTI-SERUM 

 Here the mode of procedure is of the same nature. A 

 given amount of anti-S is added to salt solution in two 

 series of tubes. To the A tubes increasing amounts of pure 

 C are added ; to the B tubes the same amounts of a mixture 

 of C and Cd in equal parts. One and a-half hours at 37 C. 

 are allowed for combination, and then red corpuscles treated 

 with IB are added to each tube to find how much C is 

 obtainable. Examples : 



1. 0-1 c.c. anti-S in each tube. 

 A. 



1 This tube was accidentally broken. 



