42 ESSENTIALS OF BACTERIOLOGY 



complement (the completor), and one, more resistant, called 

 the amboceptor, or combiner, which unites with complement 

 and with the cell. For lysis, therefore, it is necessary that 

 ambocepter be united to the bacteria or cell, and that com- 

 plement be present or added to join with amboceptor, com- 

 pleting the circuit. Complement may be prevented from com- 

 bining with amboceptor by "deviation of the complement." 

 The amboceptor may be in excess, and the free group absorb 

 or attach itself to all the available complement, leaving none 

 to join the amboceptor; or anti-complements maybe present 

 to monopolize all this complement and leave none free to unite 

 with amboceptor. This deviation prevents lysis. 



Fixation of Complement. By adding a definite standardized 

 complement to a mixture of antigen and amboceptor of a 

 similar kind the complement is bound or fixed, and none is 

 left free. If the amboceptor is not like the antigen, the com- 

 plement will not unite the two, will not be bound, and is free 

 to unite with any other amboceptor that may be introduced. 

 If this be a hemolytic amboceptor, and red corpuscles are 

 added as an indicator, the cells will lose their hemoglobin, 

 because hemolysis will occur from the completing of the re- 

 action. The complement will unite to hemolytic ambocep- 

 tor, since it is not fixed or bound by the other amboceptor, 

 and the other amboceptor is not of the same nature as the 

 antigen. This is the principle of the Wassermann serum re- 

 action or test. 



Anaphylaxis or Allergy. Under certain circumstances 

 the second injection of a proteid as antigen instead of render- 

 ing immune, produces hyper sensitiveness. Behring, in 1892, 

 noticed this with injections of antitoxin, and called it "hyper- 

 susceptibility." 



Richet, in 1904, called a similar condition anaphylaxis, or 

 the reverse of prophylaxis, and von Pirquet introduced the 

 term "allergy" "altered reactivity" to express the same thing. 

 Guinea-pigs may be rendered so sensitive by o.ooi c.c. of 

 horse-serum that a second dose within a week or a few days 

 produces fatal shock. 



