340 BACTERIOLYSINS 



peratures below 80 C. They cannot apparently be increased by im- 

 munization, the quantity present in each leukocyte being probably at 

 all times just sufficient for the digestion of a limited number of bacteria, 

 which can be ingested at one time by the individual leukocyte. It 

 is probable that the excess of bactericidal substance is thrown off into 

 the blood-stream, representing the serum bacteriolysins, and at least 

 indicating that the leukocytes are one source for the production of bac- 

 teriolytic amboceptors. 



Mechanism of Bacteriolysis. According to the side-chain theory 

 of Ehrlich a bacteriolysin is an antibody of the third order, or an ambo- 

 ceptor furnished with two haptophore or grasping arms for uniting the 

 bacterium on one side with a suitable complement on the other. The 

 antibody, therefore, acts simply as an interbody or connecting link; 

 it is specific for the bacterium causing its production, but is unable itself 

 directly to injure the bacterium, lysis being brought about by an at- 



tached complement. Bacteriolysis is, 

 therefore, an interaction of ambocep- 

 tor and complement upon the bacterial 



FIG. 95. THEORETIC STRUCTURE 



OF A BACTERIOLYTIC AMBOCEP- While bactenolytic amboceptors 



T . OR '. will unite with their antigens under 



A, Amboceptor; C, comple- 

 ment; r, receptor of bacillus; h, practically all conditions, nevertheless 



a suitable Complement may not be 



of the amboceptor. present, and hence a bacteriolytic 



serum may not be active in all animals. 



The influence of bacteriolysins upon endotoxins is a question of con- 

 siderable interest and importance. As the result of convincing experi- 

 ments performed, especially by Pfeiffer, it is evident that a bacteriolytic 

 serum does not neutralize the endotoxin at the time the bacterium under- 

 goes disintegration. Highly immune serums appear to be unable to pro- 

 tect an animal against the endotoxins, and, indeed, may even increase the 

 intoxication and, by liberating an excess of endotoxin, kill the animal. 



The bactericidal substances derived from leukocytes are, however, 

 apparently capable of neutralizing endotoxins, to some extent at least, 

 as Hiss and Zinsser were unable to ascribe the beneficial effects of leu- 

 kocytic extracts to the bacteriolytic action alone. 



As mentioned elsewhere, both Metchnikoff and Bordet maintain 

 that the bacteriolysin is in the nature of a "sensitizer," preparing the 

 bacterium for the action of the alexin or cytase, just as a mordant aids 

 in the penetration of a dye-stuff. 



