158 ANTIGENS AND THE TECH NIC OF SERUM REACTIONS 
combining with the non-specific complement. According to this 
theory the union of complement to specific cell takes place through 
the amboceptor. Bordet maintains that neither the specific cell (anti- 
gen) of itself nor the substance sensibilitrice (amboceptor) of itself 
unites with alexin (complement) ; when both are simultaneously 
present, however, alexin is absorbed. In other words, amboceptors 
as such do not exist, according to this view, and consequently com- 
plement cannot be bound to the specific cell by a complementophile 
(haptophore) group. ^ 
Multiplicity of Amboceptors and Complement.— The researches of 
Xuttall and Buchner and of Moxter- have shown that fresh normal 
serum possesses definite but limited bactericidal powers, apparently 
not specific (for a variety of bacteria may be destroyed) which are 
destroyed by an exposure of thirty minutes to 55° C. Furthermore, 
the "inactivated" serum appears to regain its original bactericidal 
value for various organisms when it is mixed with a relatively small 
amount of normal serum. In other words, normal serum and specific 
immune serum (unheated) alike appear to depend upon thermostab- 
ile amboceptor and thermolabile complement for their bacteriolytic 
and hemolytic activities. They differ in the highly specific potency of 
the immune serum for its homologous cell. Ehrlich and Morgenroth^ 
believe that the normal or natural cytolytic activities of sera depend 
upon a multiplicity of specific amboceptors, each specific for its red 
blood cell or other cell, and Pfeiffer^ has made similar observations 
for the normal bactericidal powers of blood. Bordet and Gay^ deny the 
multiplicity of complement. 
Fixation of Complement.— Bordet and Gengou,^ in a series of experi- 
ments, brought forth experimental evidence of the unity of com- 
plement and, incidentally, developed a method of investigation now 
extensively utilized to demonstrate the presence of various specific 
immune antibodies. If a specific immune body (as for example, 
the serum of an animal immunized to typhoid bacilli) is heated to 
55° C. for one-half hour, then added to a suspension of typhoid bacilli 
together with normal unheated serum, a union between the bacilli, 
the specific antibody of the serum (amboceptor, substance sensibili- 
trice) and the complement (alexin) will take place. If the propor- 
tions of the three reactive bodies are correct, all the complement or 
alexin will be bound, proA'ided the mixture is incubated a few hours 
at 37° C. If, now, red blood cells and inactivated immune serum 
specific for the red blood cells are added to the mixture of bacteria 
immune body and complement, no hemolysis should be noticed, 
because the complement is ciuantitatively anchored to the bacteria- 
1 Besredka: Bull. Inst. Pasteur, 1903, 1, 547, 579. 
^ Loc. cit. 3 Loc. cit. 
* Harben Lecture: Jour. Roy. Inst. Public Health, 1909, 17, 385. 
=> Collected Studies in Immunity by Bordet and his associates (translated by Gay, 
1909). 
« Ann. Inst. Pasteur, 1901, 15, 289. 
