The Deviation of the Complement 137 



in the experiment. Neisser and Wechsberg attribute the peculiar 

 reaction to the fact that there being more amboceptors than com- 

 plements in the serum, some of the former satisfy their combining 

 affinities by attaching themselves to the bacteria, some by attach- 

 ing themselves to the complement, instead of forming combinations 

 of all three. If under these circumstances the serum containing 



gX 



c9 9 9 



rf9 9 • 



Fig. 29. — Diagram illustrating the Neisser- Wechsberg phenomenon of "de- 

 viation of complement." In A^ the three black units (c) represent the quantity 

 of complement necessary for the dissolution of a bacterium, and the three white 

 units (i) the intermediate bodies or amboceptors through which they may act. 

 A' shows these properly proportioned units properly combined and anchored to 

 the bacterial cell which will be destroyed. If an excess of amboceptor units be 

 present, as is suggested in B^, the resulting combinations and the consequent 

 results may vary according to the difEering combining afiSnities. Thus, B^ shows 

 an unchanged affinity, i.e., only those amboceptors unite with bacterial cells 

 that are charged with complement. C shows equal affinity of the amboceptors 

 for complement and for the bacterial cell, so that charged or uncharged units 

 attach themselves to the cell, diminishing the complementary action. D' shows 

 the possible result when the affinity of the amboceptor for the bacterial cell is 

 diminished after charging with complement, so that though the complement and 

 amboceptor combine, there can be no destruction of the bacterium. Thus, excess 

 of the amboceptor units may "deviate the complement" and prevent its action. 



the amboceptors is diluted until their number becomes approximately 

 equal to the number of complements introduced, any deviation 

 resulting from inequality of the combining affinities becomes im- 

 probable. Bordet and Gay,* however, have performed experiments 

 tending to show that these elements do not really unite, thus seem- 

 * "Ann. de I'lnst. Pasteur," June 25, 1906, xx, No. 6, pp. 267-498. 



