1904.] On Chemical Combination and Toxic Action, etc. 307 



matter how large amounts of immune-body and complement are used ; 

 in only one case did we get a considerable amount of lysis, about three- 

 fourths. We never obtained complete lysis, however. In other words, 

 the ox's serum does not " complement." Is this due to want of 

 combining power of the ox's complement, or to the deficiency of toxic 

 action 1 This question can be answered by finding the amount of 

 complement taken up when varying amounts of immune-body are used. 

 The scheme is : 



Ox's O + n IB + x ox's C | guinea-pig's Q + IB. 



As lysis does not occur in the first stage, the contents of each tube 

 are centrifugalised, and the fluid is added to the guinea-pig's corpuscles. 

 The following results were obtained : 



Experiment LXXIII. 1 D of IB took up 0'04 c.c. ox's C. 

 * ., 0-05 



O 



5) }J J> 



Dose of ox's complement for guinea-pig's corpuscles = 0'03 c.c. 

 Experiment LXXIV. 1 D of IB took up O'OU c.c. ox's C. 







Q 



0-02 



J) J) )J 



Dose of ox's complement for guinea-pig's corpuscles = 0'02 c.c. 



From these it is evident (1) that a considerable amount of ox's comple- 

 ment is taken up by one dose of immune-body (i.e., by 1 M.H.D. as tested 

 with rabbit's or guinea-pig's complement), but this amount of comple- 

 ment, which may be more than sufficient to produce complete lysis of 

 rabbit's or guinea-pig's corpuscles, produces almost no lysis of the ox's 

 corpuscles, and (2) the total amount of complement which can be taken 

 up is almost reached with one dose of immune-body, additional doses 

 of immune-body scarcely increasing the amount. There is, of course, 

 in this case, no possibility of the phenomenon being due to dissociation 

 of complement after combination, as the ox's corpuscles are removed by 

 centrifugalisation before the guinea-pig's corpuscles are added, and, 

 therefore, any complement obtainable must have been free in the fluid. 

 Accordingly, we have here, again, an example of the relative non- 

 sensitiveness of an animal's corpuscles to the action of its own comple- 

 ment when it is brought into union with them by an immune-body. 

 But, in addition, there is, unlike the two previous cases, a deficiency 

 also in the combining power of complement beyond a certain point, or, 

 in other words, only a small proportion of the molecules of the red 

 corpuscles combined with immune-body (R + IB molecules) take up 

 ox's complement. 



The fact that in the case just described, only some of the E + IB 

 molecules take up complement is of considerable theoretical importance. 



