198 



COLLECTED STUDIES IN IMMUNITY. 



Case V. Dog blood inactive serum of goats immunized with 



dog blood. 



The various means by which we have succeeded in a separation of 

 the single complements are as follows: 



1. Digestion with papain. 



2. Partial destruction with an alkali. 



3. Partial destruction by heating to 50 C. 



4. Combination with blood-cells. 



We discovered that invariably under the influence of papain 

 digestion four complementing actions disappeared, or were more or 

 less strongly diminished. Only a single complement remained intact, 

 namely, that fitting the amboceptor developed in goat serum through 

 immunization with rabbit blood. 



In these experiments 20 cc. goat serum mixed with 3 cc. of a 10% 

 papain solution were placed in an incubator in order to digest the 

 complements. We found that the proper time to interrupt the 

 digestive process was usually thirty to forty-five minutes later, 

 when an examination 1 demonstrated complete preservation of the 

 complements for Case III with complete disappearance or consider- 

 able diminution of the others. Of the large number of our experi- 

 ments made in this connection three examples may be cited. See 

 Table I. 



TABLE I. 

 DIGESTION OP GOAT SERUM BY MEANS OP PAPAIN. 



1 In all our experiments the amount of blood used as a reagent was 1 cc. 

 of a 5% suspension. 



