1904.] On Chemical Combination and Toxic Action, etc. 299 



evidence of the degree of chemical affinity between the complements 

 and the immune-body. But it is manifest that theoretically a com- 

 plement may combine perfectly through the medium of the immune- 

 body, and yet produce little hsemolysis, owing to the absence of 

 sensitiveness to the zymotoxic group combination or "complementing" 

 may occur and yet haemolysis be deficient or absent. The question 

 which we have investigated is accordingly this Where different 

 complements differ in their action as shown by the dosage, both of 

 complement and of immune-body required, does this depend upon 

 differences in their combining affinities or upon differences in their 

 toxicity ? 



In working out this problem we have made use of three sera, viz. : 

 (a) the serum of the rabbit injected with ox's corpuscles, therefore 

 haemolytic towards ox's corpuscles, (b) the serum of the rabbit injected 

 with guinea-pig's corpuscles, (c) the serum of the guinea-pig injected 

 with rabbit's corpuscles. In each case the hsemolytic serum is deprived 

 of its complement by heating at 55 C. and, therefore, contains only 

 immune-body ; it is accordingly inactive until complement (i.e., normal 

 serum) is added. 



In this and the other tables the following abbreviations are used : 

 IB = immune body, and v. is placed before the name of the animal 

 on whose corpuscles the immune-body acts, thus IB rabbit v. guineorpig 

 signifies the immune-body obtained from the rabbit, and acting on 

 guinea-pig's corpuscles, C = complement, ID = one hsemolytic dose 

 (of IB or C as the case may be). 



In the first place, we may give in tabular form, the average dosage 

 of the several complements with the different immune sera : the test 

 amount of corpuscles being 1 c.c. of a 5-per-cent. suspension in 

 0'8 per cent, sodium chloride solution. 



* The normal serum of the ox has a strong hsemolytic action both on rabbit's 

 and on guinea-pig's corpuscles. This is due to the presence of a natural immune- 

 body, and it is not possible to remove this in the usual way by placing the serum in 

 contact with the corpuscles at C. We have, however, made allowance for thi? 

 circumstance, and the dosage of complement has been calculated accordingly, and 

 may be taken as substantially correct. 



VOL, LXXIV. ^ A 



