148 THE PRINCIPLES OF IMMUNOLOGY 



NEISSER-WECHSBERG PHENOMENON (Continued) 



_ Amount Inactivated Fresh guinea- Number of colonies 



Controls o f culture immune serum pig serum on plates 



1 1/5000 c.c. ... ... Many thousands 



2 1/5000 c.c. o.oi c.c. . . . Many thousands 



3 0.01 c.c. . . . None 



4 1/5000 c.c. ... 0.3 c.c. Many thousands 



5 ... i.o c.c. None 



The broth culture is so diluted that 0.5 c.c. are added to each tube. All tubes 

 are made up to constant volume with 0.85 per cent, salt solution. Incubation is 

 for three hours at 37 C, after which five drops from each tube are added to 

 a tube of melted agar for plating. 



The Neisser-Wechsberg method not only presents a means of work- 

 ing with bactericidal sera but also demonstrates both the necessity for 

 the presence of complement to complete the bactericidal amboceptor 

 and the appearance of inhibition zones in the stronger concentra- 

 tions of the immune serum. Neisser and Wechsberg interpreted the 

 inhibition zone as illustrating what they called " complement devia- 

 tion," a term frequently used incorrectly as synonymous with com- 

 plement fixation. They believed that if an excess of amboceptor units 

 is present, a certain number of these units will combine with the avail- 

 able complement units, thus leaving a number of amboceptor units 

 unsaturated with complement. The amboceptor is present in amounts 

 too large to be entirely absorbed by the antigenic bacteria and therefore 

 it is assumed that a certain number of the free amboceptor units 

 combine with a number of complement units, thus preventing a suf- 

 ficient amount of complement to combine with the amboceptor units 

 already absorbed by the bacteria for the process of bacteriolysis. In 

 tubes four to nine of the preceding protocol the amboceptor units and 

 bacteria are closely enough balanced to ensure complete absorption 

 of amboceptor and thus permit of full action of complement ; there 

 being no free amboceptor, there is no " deviation " of complement. 

 Except for the possible evidence afforded by the Ehrlich and Sachs 

 experiment (see page 125) there is no other experimental evidence sup- 

 porting the view that free amboceptor may enter into combination 

 with complement. Gay has suggested that the inhibition may be due to 

 precipitation by the interaction of the immune serum and bacterial 

 protein which may have gone into solution, the precipitate operating 

 to fix complement and prevent its combination with bacteriolytic am- 

 boceptor. Whilst precipitation may undoubtedly be of significance in 

 this connection, we are of the opinion that the resemblance to col- 

 loidal reactions as described in connection with precipitation and agglu- 

 tination, wherein excess of one colloid may prevent the occurrence of 

 precipitation or flocculation, offers an equally satisfactory explanation 

 ;for the Neisser-Wechsberg phenomenon and that we are therefore 

 justified in regarding the reaction as illustrating " inhibition zones " 

 where the concentration of amboceptor is great. The failure of bac- 

 teriolysis in tubes eleven and twelve is due, of course, to insufficient 

 amount of amboceptor. The control tubes show that neither ambo- 

 ceptor nor complement alone is capable of producing bacteriolysis. 



Buxton's Method for Bacteriolysis. Buxton determined that 



