326 CYTOLYSINS 



obtain an approximate estimate of the content in bacteriolytic ambo- 

 ceptors after the same manner. 



The technic of these tests is given in the chapter on Bacteriolysins. 



COMPLEMENTS 



Historic. As early as 1876 Landois described the hemolytic action 

 of fresh blood-serum upon the blood-corpuscles of animals of certain 

 species. Traube and others observed that animals could withstand the 

 injections of relatively large amounts of septic material, but it was not 

 until 1886-90 that Fodor, Nuttall, Buchner, and others fully established 

 the bactericidal properties of fresh blood-serum. Buchner demon- 

 strated the fact that the active principle causing bacteriolysis or hem- 

 olysis is very labile, and can be inactivated by a temperature of 55 C., 

 by dialysis, or by dilution with distilled water. He designated the 

 active principle "alexin." 



Subsequently, in 1899, Bordet found that the alexin of Buchner was 

 composed of two distinct substances one a sensitizing substance, which 

 is thermostabile, and a second, the thermolabile substance. Somewhat 

 later (1899) Ehrlich and Morgenroth confirmed these observations, but 

 applied the name "amboceptor" to the sensitizing substance and 

 "complement" to the alexin. These terms are most widely employed 

 at the present time. Bordet adheres to the term alexin, meaning thereby 

 the thermolabile principle, and does not use it in the original sense of 

 Buchner, which included both the sensitizing substance and the alexin. 

 MetchnikofFs cytases are practically the same as Ehrlich's complement 

 and Bordet's alexin. 



Definition. Complement [Lat., complementum, that which completes] 

 is the substance, present alike in normal and in immune serum, which is 

 destroyed by heating to 55 C., and which acts with an amboceptor to produce 

 lysis. 



As mentioned in the discussion on amboceptors, the complement is 

 the active lytic substance concerned in the phenomenon of cytolysis, 

 but is powerless until united with the cell, corpuscle, or bacterium by 

 means of the interbody or amboceptor. 



Structure and General Properties of Complement. Complement is 

 ordinarily not attached to the body-cells and is free in the blood-serum. 

 According to Ehrlich, complement is simple in structure, and is composed 

 of a haptophore portion for union with the complementophile hapto- 

 phore of an amboceptor, and a second toxic or lytic portion, called the 



