ORIGIN AND STRUCTURE OF COMPLEMENT 73 



Origin of Bacteriolytic Amboceptors. Regarding the origin of the 

 bacteriolytic amboceptors, our knowledge is as yet very meagre. 

 The researches of Pfeift'er and some of his pupils suggest that the 

 spleen is possibly more actively concerned in their production than 

 any other organ, but there is also evidence to show that they may be 

 formed in the tissues at large. 



Relative Importance of Amboceptor and Complement. As to the 

 relative importance of amboceptor and complement, opinions differ. 

 Ehrlich regards the amboceptor merely as an indifferent connecting 

 link between the bacteria and the complement, and Bordet also 

 views the complement as the essential factor in bacteriolysis, the 

 amboceptor playing the role of a mordant or activator ; on the other 

 hand, Pfeiffer emphasizes the greater importance of the amboceptor 

 and likens its role to that of a preferment with the complement 

 playing the role of the corresponding kinase. In support of this 

 view he calls attention to the fact that as a result of immunization 

 (infection, vaccination) only the amboceptor is increased, while the 

 complement content is not affected, and further, also, that during the 

 process of hemolysis (which is in every respect closely related and 

 directly comparable to bacteriolysis) the complement is active, not 

 in proportion to its absolute amount, but in accordance with its 

 concentration; this would be quite in harmony with the supposition 

 that its action in reference to the amboceptor is essentially that of 

 a catalyzing agent. 



Origin and Structure of Complement. Regarding the origin and 

 structure of the complement our knowledge is likewise imperfect, 

 though somewhat more definite than that concerning the ambo- 

 ceptor. While originally it was viewed as a single substance, Ferrata 

 has shown that on dialysis the complement separates into two com- 

 ponents, one of which is carried down in the precipitate of globulins 

 the so-called middle piece (Mittelstuck), while the other remains in 

 solution the end piece (Endstiick). Of the two, as the term indi- 

 cates, the first named (Mittelstuck) unites with the combination of 

 bacteria (sc., blood corpuscles) and the corresponding amboceptor, 

 while the end piece only exercises its activity after this union has been 

 effected. Either fraction alone possesses no bactericidal properties 

 in the presence of a suitable amboceptor, though it appears that 

 either component can in a measure supplement the action of the 

 other, in the sense that a very small quantity of the globulin fraction 



