

1904] On Chemical Combination and Toxic Action, etc. 303 



experiment of this kind may be graphically represented as before, 

 thus : 



Guinea-pig's Q+nlB + x rabbit's C Guinea-pig's Q + IB. 



In performing experiments of this kind we found that five or even 

 ten doses of immune-body apparently led to the taking up of scarcely 

 more complement than one dose of immune-body did; and further 

 that the amount of complement apparently taken up seemed to 

 become less, the longer the test corpuscles were left in the fluid. Thus, 

 for example, at the end of 2 hours, 15 c.c. of complement might 

 appear to be taken up, and next morning only -05 c.c. It appeared, 

 therefore, (a) that multiple doses of immune-body did not lead to 

 the taking up of corresponding multiple doses of complement, and 

 (b) that the complement taken up appeared to dissociate again in 

 part, though this phenomenon might possibly be due to the presence 

 of some complement molecules with very slow action. When, however, 

 we used as the indicator ox's corpuscles treated with their corresponding 

 immune-body, quite different results were obtained. The scheme is 

 now : 



Guinea-pig's Q + n IB + x rabbit's C | + Ox's Q + IB. 

 The following results will serve as examples : 



Experiment LX. 1 D of IB took up 0.2 c.c. rabbit's C. 

 3 ,, 0*45 ,, ,, 



10 1-16 



The M.H.D.. of C was only 0*1 c.c. before the experiment ; it is possible that it 

 may have increased subsequently. 



Experiment LXVIIL 2 D of IB took up 0-28 c.c. rabbit's C. 

 5 0-58 



10 0-74 



The M.H.D. of C was 0'06 c.c. 



It is thus seen that when ox's corpuscles suitably treated are used 

 as the indicator, the amount of complement taken up increases as the 

 amount of immune-body is increased, though there is a greater 

 deviation from strict arithmetical proportion than when guinea-pig's 

 complement is used. 



The difference in the results obtained with the two indicators 

 (guinea-pig's and ox's corpuscles respectively), is manifestly due to 

 the fact that there is in the rabbit's serum a complement which acts 

 on guinea-pig's corpuscles, and not on ox's corpuscles, and that this 

 complement either becomes dissociated from the guinea-pig's corpuscles 

 or combines in very small amount. On the other hand the chief 

 complement present acts on both varieties, and its union is a firm one ; 



