I40 ■ Immunity 



the number of bacteria, one can determine the exact bacteriolytic value of the 

 mixture. By taking out and planting drops from time to time the rapidity of 

 bacteriolysis can be determined, and by plating out the drops and counting {he 

 colonies one may arrive at percentages of destruction and express the bacteriolytic 

 process in the form of a curve. 



THE DEVIATION OF THE COMPLEMENT, OR THE "NEISSER-WECHSBERG 



PHENOMENON" 



A peculiar phenomenon has been observed and studied by Neisser 

 and Wechsberg.* When an animal whose blood-serum is normally 



A' n C7 V? A^ 



B^ 



c < * 9 



D I • • 



Fig. 23. — Diagram illustrating the Nfeisser-Wechsberg phenomenon of ''de- 

 viation ot 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 (6) 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 differing combining affinities. 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 6r uncharged units 

 attach themselves to the cell, diminishing, the complementary action. B^ 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. 



possessed of a high degree of germicidal power is immunized by 

 repeated injections of a bacterial antigen, its serum when examined 

 by the usual methods fails to show the usual increase in the specific 



* "Munch, med. Wochenschrift," April 30, 1901, xlviii, No. 13, p. 697. 



