76 PROPERTIES OF H^MOLYTIC SERA 



Note. The amount of complement taken up is calculated from 

 the point at which free complement is obtainable after time has 

 been allowed for combination. It will be noticed that the amount 

 of complement taken up is approximately, though not strictly, pro- 

 portional to the amount of immune-body present. The divergence 

 is more marked when higher multiples are used, as has been noted 

 in the case of another combination (p. 32) ; here also what has 

 been described as the ' Ehrlich phenomenon ', is seen to a slight 

 extent. As, however, there is very little evidence of dissociation 

 of complement after it has combined, the phenomenon in this case 

 is due to some other cause, probably to the presence of comple- 

 mentoid. 



(b) With Rabbit's Complement 



It will be seen from the tables that (a) the minimum 

 hsemolytic dose of immune-body in this case is small about 

 a tenth of that necessary when guinea-pig's complement is 

 used, and (b) that the dose of complement also is compara- 

 tively small, in fact, practically the same as that necessary 

 for the haemolysis of ox's corpuscles. The difference in the 

 doses of rabbit's and guinea-pig's complements for ox's 

 and guinea-pig's corpuscles respectively is thus very note- 

 worthy. In investigating the amount of rabbit's comple- 

 ment taken up by means of multiple doses of immune- 

 body, interesting and at first very puzzling results emerged. 

 An experiment of this kind may be graphically represented 

 as before, thus : 

 Guinea-pig's O + n IB -f x rabbit's C i Guinea-pig's O + 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 comple- 

 ment apparently taken up seemed to become less the 

 longer the test corpuscles were left in the fluid. Thus, for 

 example, at the end of two hours, 045 c.c. of complement 

 might appear to be taken up, and next morning only 0-05 c.c. 

 It appeared, therefore, (a) that multiple doses of immune- 



