224 



COLLECTED STUDIES IN IMMUNITY. 



only a slight degree of solution. For the sake of clearness it was 

 especially fortunate that the complementing amounts should happen 

 to be identical in the two cases. 



A parallel series of experiments was then undertaken with these 

 two cases, as follows: Varying amounts of the guinea-pig serum were 

 mixed each with 0.4 cc. of ascitic fluid inactivated at 56 C., and 

 the mixtures kept at room temperature for half an hour, after which 

 the binding was entirely completed. 1 Thereupon the blood-cells 

 loaded with amboceptor were added. The result of these experiments 

 is shown in the following table : 



CASE A (Ox BLOOD + AMBOCEPTOR). 



CASE B (SHEEP BLOOD + AMBOCEPTOR). 



We see, therefore, that in case A the complement protects com- 

 pletely against 2J times the complete solvent amount of complement, 

 while the amount of serum required to effect complete solution increases 

 more than twelve times. In case B, on the contrary, the complete 

 solvent dose of guinea-pig serum remains unchanged, and the series 

 proceeds just as though there had been no addition of antieomple- 

 ment. 



These experiments, which were repeated many times, therefore 



1 The union of complements and anticomplements, analogous to the behavior 

 of certain toxins and antitoxins, is dependent on the time. Hence here also 

 this had to be considered and sufficient time allowed for the mixture to act 



