1904.] Combining Properties of Serum- Complements, etc. 



11 



prevented from combining with the R + IB molecules by means of a given amount 

 of Cd. 



(2) Complementoid combines with anti-complement, and prevents 

 the union of the latter with complement. 



If the ordinary action of anti-complement is shown thus, 



Anti-C + C 



0<I R B 



Result = no 



then we may represent the effect of Cd by the following scheme 



Ariti-C + Cd 



+ o 



R 

 IB 



Result = partial lysis. 





The following are the details of such an experiment : 



Two series (A and B), of nine tubes, each containing 0'5 c.c. salt 

 solution. 



C of guinea-pig M.H.D. = 0'03 c.c., Cd = the same serum heated. 

 Anti-C is the serum (heated at 57 C.) of a rabbit injected with 

 guinea-pig's serum. 



Series A. Each tube receives O'l c.c. anti-C and O'l c.c. Cd. 



Series B. To each tube, (H c.c. anti-C alone is added. 



All the tubes are placed in the incubator for an hour at 37 C. 



To the several tubes of both series alike are then added increasing 

 amounts of C, viz., 0'03, 0'04, O05 c.c., etc. Incubation for another 

 hour. To each tube the standard amount of red corpuscles treated with 

 IB is then added, and the tubes are incubated for another hour. 



The results are shown in the following table : 



The effect of Cd in preventing the combination of C is thus seen 

 throughout. If we take the first tube, it is seen that the previous 

 addition of (H c.c. Cd has kept out sufficient C to produce lysis of 

 0'68 of the added corpuscles, i.e., about 0'02 c.c. C. 



