190 COLLECTED STUDIES IN IMMUNITY 



The combination, sheep blood and rabbit serum (Buchner's 

 second case) presents entirely analogous conditions. Both guinea- 

 pig serum and human serum, the latter only in a moderate degree 

 contain a complement which activates the amboceptor of rabbit 

 serum. The rabbit amboceptor, however, is evidently of more stable 

 constitution; for even after heating to 60, its solvent power can 

 be completely restored. I can therefore confirm the facts found 

 by Buchner in this case, namely that sheep serum is incapable of 

 restoring the solvent power for sheep blood. This, however, accord- 

 ing to the above statement, is naturally no argument against the 

 complex nature of the hamo ysin because not every serum need con- 

 tain a fitting complement for every particular amboceptor. 



Provided that sufficiently numerous combinations are examined, 

 the " completion method " as a rule leads to the positive demon- 

 stration of the amboceptors. The " separation in the cold " on 

 the contrary, owing to the peculiarity of the combining relations 

 of the separate components, is entirely inapplicable in a number 

 of cases. 



Gruber, the second author to come out against the conception of 

 the complex nature of normal serum hsemolysins, sought to demon- 

 strate amboceptors in a number of normal sera, by means of " sepa- 

 ration in the cold." In view of the preceding it is not surprising that 

 he failed in a number of cases to effect a separation of the hsemolysin. 



Ehrlich and Morgenroth in their second communication on hae- 

 molysins have already analyzed the conditions for separating the 

 interbody by means of absorption, emphasizing " that the solution 

 of the problem therefore is now possible only under either of the two 

 above mentioned favorable conditions; (1) When the two haptophore 

 groups of the interbody differ greatly in their affinity; and (2) when, 

 by means of a combination whose discovery depends on chance, an acti- 

 vating complement is found." 



The limitations of the two methods applicable to an analysis 

 of the complex nature of hsemolysins, are therefore sharply defined. 

 In any individual case when one method fails, it will always be 

 be necessary to make use of the other in order to gain an insight 

 into the constitution of the haemolysins at all commensurate with 

 the means at our disposal. The schematic application of only one 



activated after heating to 55 C. can be shown to exist in active horse serum 

 (which does not dissolve guinea-pig blood) by combining and completing it with 

 guinea-pig serum. 



