208 COLLECTED STUDIES IN IMMUNITY. 



If we review all our observations, they show that in the ques- 

 tion of the complements the Unitarian conception leads to a con- 

 fused mass of inexplicable contradictions, and that it must there- 

 fore be abandoned. All experiences, on the other hand, harmonize 

 best with the assumption of a number of different complements in the 

 .same serum. Sober consideration, in fact, makes this appear as 

 the necessary consequence of such a multiplicity as has been demon- 

 strated anew by these experiments. It is a satisfaction to know 

 that in the Institut Pasteur a high authority (Metchnikoff ) * has 

 also given up the Buchner-Bordet conception of the simplicity 

 [einheitlichkeit] of the alexines, and has come to the conclusion 

 that there are at least two complements in the same serum. Metch- 

 nikoff found that the exudates rich in macrophages acted hsemo- 

 lytically, but were unable to effect bacteriolysis. On the other hand 

 the exudates rich in microphages exerted a marked bactericidal action, 

 but were incapable of dissolving even sensitized red blood-cells. 

 Metchnikoff concludes that these two kinds of cells produce two 

 different complements, one, which he terms microcytase, effects the 

 bacteriolytic actions, the other, macrocytase, is the carrier of the 

 functions which destroy animal cells. He emphasizes that the 

 demonstration of the duality of complements does not affect the 

 correctness of Bordet's experiments, and he says in explanation of 

 Bordet's results: " II n'y a qu'a admettre que les elements figures, 

 une fois qu'ils sont impregne's de fixateurs specifiques, deviennent 

 capables d'absorber non seulement la cytase qui les digere, mais 

 aussi une autre qui, sans les dissoudre, se fixe simplement sur eux." 



So far as this is concerned we should like again to emphasize 

 that we also have not questioned the correctness of Bordet's experi- 

 ments, but have merely objected to the Unitarian conception deduced 

 therefrom. The old controversy concerning the two views would thus 

 <be ended, and definitely decided in favor of our view. 



1 Metchnikoff, L'Immunite dans les maladies infectieuses, page 206, Paris, 

 1901. 



