74 THE BACTERICIDAL SUBSTANCES OF THE BLOOD 



of the serum (middle piece) is sufficient to effect bacteriolysis, pro- 

 viding that a sufficiently large amount of the end piece is present; and 

 vice versa, the germicidal properties of the end piece are enhanced by 

 increasing the amount of the middle piece. Since the middle piece 

 of different animal sera is interchangeable, the thought suggests 

 itself that the two complement components in the living animal are 

 actually present as separate substances. The apparent absence of 

 complement in various sera which we have noted above, might thus 

 be due to the absence or deficiency in the end piece only, rather than 

 to actual absence of complement as a whole. 



Complementoid. This conception of the duality of the complement 

 is quite in accord with the original view of Ehrlich and Morgenroth 

 regarding its structure, according to which the substance in question 

 contained a combining (haptophoric) group which effects the union 

 with the amboceptor and a second (toxophoric or zymophoric) group 

 to which the action of the complement is essentially due. When 

 this latter group is destroyed, while the first remains active, so-called 

 complementoid results, which would mean in more modern parlance 

 that the middle piece remains, while the end piece has been destroyed 

 or altered so as to be rendered inactive. 



Chemical Nature of Amboceptor and Complement. Regarding the 

 chemical nature of amboceptor and complement our knowledge is 

 very meagre. Liebermann has pointed out that a certain analogy 

 exists between the action of amboceptor and oleic acid. Oleic acid 

 and hog serum together will thus cause the almost instantaneous 

 hemolysis of hog corpuscles, while the serum by itself is inactive, 

 and the same quantity of oleic acid alone brings about the lysis of 

 the corpuscles only very slowly. This observation is suggestive, 

 but can hardly be taken to prove the identity of the hemolytic 

 amboceptor and oleic acid, especially in view of the highly specific 

 action of the various amboceptors. 



Complement, on the other hand, has been viewed as a compound 

 of albumin with a lipoid (Noguchi and Liebermann). Noguchi thus 

 found that mixtures of soaps and inactivated guinea-pig serum, while 

 inactive by themselves, caused the hemolysis of red corpuscles which 

 had been previously treated with amboceptor. He himself, however, 

 points out that the action of such artificial complement is materially 

 slower than that of the native serum. But notwithstanding this and 

 other points of similarity between active and artificial complement, 



