356 CYTOLYSINS 



may result in more harm than good. As has been pointed out by Neisser 

 and Wechsberg, more amboceptors may be introduced than can be taken 

 up by the bacteria causing the infection, and those that remain free are 

 capable of combining with some of the complement that is present, and 

 thus prevent a portion of the complement from acting with the ambo- 

 ceptors attached to the bacteria i. e., the complement has been de- 

 viated or deflected from its natural course. This would really mean a 

 decrease in bacteriolysis, but while deviation of complement has been 

 demonstrated as a fact, its importance in serum therapy is probably 

 overrated and has certainly not been definitely proved. 



QUANTITATIVE TITRATION OF 



Titration of Hemolytic Complement. The quantity of a hemolytic 

 complement present in a fresh serum for certain corpuscles may be 

 measured in the same manner as hemolytic amboceptors are measured, 

 namely, by adding to a series of test-tubes increasing amounts of the 

 fresh serum with a constant dose of an emulsion of corpuscles and a 

 constant and sufficient dose of the corresponding hemolytic amboceptor 

 for these corpuscles. After a suitable period of incubation, that tube 

 that shows complete hemolysis contains just sufficient complement, or 

 one unit. Since we know how much complement serum was placed in 

 this tube, we now know that this quantity contains one unit of hemolytic 

 complement. Of course, the amount of corpuscles and amboceptor must 

 be constant in all tubes; if the quantity or quality of one or both of these 

 is altered, the unit of complement will vary. 



Titration of a Bacteriolytic Complement. The quantity of bacterio- 

 lytic complement in a given amount of fresh serum may be determined 

 in a similar manner, although far less accurately, for instead of viewing 

 the results of lysis in the test-tube as we can do in hemolysis, the degree 

 of lysis must be determined by plating out the mixtures to determine the 

 relative numbers of living and dead bacteria. The degree of bacterio- 

 lysis may, however, be viewed after a manner with the aid of the micro- 

 scope. 



Gay and Ayer employ a direct method, which consists in adding 

 varying amounts of the serum to be tested to a definite volume (0.5 c.c.) 

 of a suspension of cholera vibrios, prepared by emulsifying a twenty- 

 four-hour agar culture in 10 c.c. of normal salt solution and adding a 

 constant and sufficient dose of serum from a rabbit immunized against 

 cholera. The mixtures are placed in small test-tubes and incubated for 

 one and one-half hours at 37 C. Films are then prepared, stained, and 



