PROPERTIES OF COMPLEMENTOIDS 57 



corpuscles treated with IB. With guinea-pig's Cdx, in one 

 case a similar result was obtained, whilst in another a half 

 of the Cd molecules had been removed by combination. 



Another method is to bring Cd into contact for a given 

 time with red corpuscles treated with IB (say, 3 IB), then 

 to centrifugalize and wash these corpuscles, and then test 

 how much C they will take up. The control will be red 

 corpuscles treated with the same amount of IB, but not 

 with Cd. Similar results emerge from experiments of this 

 kind. The following may be taken as an example : 



Three sets of tubes containing the standard amount of 

 red corpuscles, fully 3D of IB added to each tube. 



1. Series A. We estimate how much guinea-pig's C will 

 be taken up. 



2. Series B. We estimate how much C will be taken up 

 after the addition of 0-04 c.c. Cd (lysis having been first 

 produced by a dose of complement). 



3. Series C. The corpuscles are treated with 0-6 c.c. Cd 

 for an hour at 37 C., then centrifugalized and washed to 

 remove the free Cd. We then estimate how much C the 

 corpuscles will take up. 



The result is that in 



Series A 0-175 c.c. of C is taken up. 



B 0-15 



,, C 0-165 



In other words, after lysis the addition of 0-04 c.c. of Cd 

 has kept out 0-025 c.c. of C, whereas before lysis the addition 

 of 0-6 c.c. of Cd (fifteen times the amount) has only kept out 

 0-015 c.c. of C. It is thus seen that a mere fraction of Cd 

 entered into combination with the R + IB molecules before 

 lysis. We may add that the largest amount observed was 

 in an experiment with rabbit's Cd, where it came out that 

 of 0-25 c.c. of Cd added before lysis an amount was taken 

 up equal to 0-1 c.c. of Cd added after lysis. 



