ORIGIN AND STRUCTURE OF COMPLEMENT 77 



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 supposi- 

 tion 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 view r ed 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 (Mittel stuck), while the other remains in 

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

 cates, the first named (Mittelstiick) 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 

 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 



