AMBOCEPTOR AND COMPLEMENT 175 



being suggested as the reason. Attempts have been made to supple- 

 ment the complement present by injecting fresh normal serum with 

 the anti-serum, but without success, and some anti-micro bic sera, 

 e.g. anthrax serum, are not bacteriolytic ; this explanation is, there- 

 fore, unsatisfactory. Deflection of complement (p. 178) may occur 

 in some instances, or the complement may not be of the right kind. 

 In other cases, the organism in certain situations may be inaccessible 

 to the blood-stream and to the anti -serum, 

 e.g. the vibrios, in the bowel in cholera. 



Another reason advanced is the extreme 

 specificity of anti-serum and the variability 

 of bacteria so that many races or strains 

 of an organism may exist, e.g. of B. coli, 

 streptococci, pneumococci, etc. Hence the 

 anti-serum prepared with one race may not 

 neutralise another race. Attempts have 

 been made to overcome this factor by pre- 

 paring the anti-serum by the injection of 

 many races and so obtaining a " polyvalent 

 serum." 



FIG. 33. Diagram to 



The amboceptor or immune body show the union be- 

 seems to link the complement to the * ee " complement 



(black) and proto- 



bactermm (Fig. 33) ; complement re- p i as m of cell by 



mains free if the appropriate ambo- means of the ambo- 



u j ceptor (white). (After 



ceptor or immune body is not present, Ehrlich ) 



and bacteriolysis does not ensue (see 

 also p. 174). Complement is thermolabik, i.e. it is destroyed 

 by heating to 56 C. for thirty minutes ; while the ambo- 

 ceptor is thermostable, i.e. it is not destroyed by this 

 treatment. 



According to Ehrlich, fresh serum contains numerous 

 complements which are more or less specific for different 

 amboceptors (see also note, p. 182). When the comple- 

 ment is destroyed by heating it is converted into " comple- 

 mentoid " (analogous to toxoid). Both complement and 

 complementoid on injection give rise to anti- complement. 

 The amount of complement in different sera varies con- 

 siderably ; horse serum contains very little, guinea-pig 

 seruni much. Complement itself probably consists of two 



