708 MICROBIOLOGY OF DISEASES OF MAN AND DOMESTIC ANIMALS 



Occasionally there is noted in sera normally substances which 

 may combine with the complement and prevent this body from com- 

 bining with the amboceptor. Such substances are called anticomple- 

 ments and may be produced artificially by the immunization of animals 

 with complement. Occasionally complement is absorbed by tissue 

 cells and prevented from combining with amboceptor. In case there is 

 an excess of amboceptors in a serum and only a small amount of com- 

 plement, it may be deviated. In this case the cells will have taken up 

 all the possible amboceptor and there will be an abundance of ambo- 

 ceptor free in the serum. It has been demonstrated that complement 

 will combine with free amboceptor before it will combine with the 

 amboceptor which has been bound to the cells. * In this case all the avail- 

 able complement will be taken up by the amboceptor which is free and 

 consequently there will be no lysis. This fact is of importance in certain 

 infections where the development of bacteriolytic substances are of 

 importance and necessary in effecting a recovery. The_infectious 

 microorganisms may not be destroyed for the above reason. 



The Deflection of the Complement as a Test for Antibodies. A very in- 

 genious procedure has been devised for the testing of sera for unknown 

 antibodies similar to bactericidal substances and lysins. The method 

 of demonstrating the fixation of the complement was first worked out 

 by Bordet and Gengou. The reaction is made use of in the test for 

 syphilis which is briefly stated as follows: when the syphilitic antigen 

 is combined with the supposed amboceptor in the blood serum of the 

 suspected case of syphilis and a foreign complement, which has been 

 accurately standardized, is added, this complement is bound and is, 

 therefore, prevented from combining with red blood corpuscles, and 

 a hemolytic amboceptor which may be added later. Hemolysis is, 

 therefore, prevented. The general technic of the test is as follows: 

 the syphilitic antigen is prepared by making an aqueous or alcoholic 

 extract of the liver of syphilitic fetus or in several other ways. This 

 antigen is supposed to contain protein and other chemical substances 

 produced by the Treponema pallidum, the etiological microorganism 

 of syphilis or similar substances to those produced by this micro- 

 organism. The blood serum of the suspected case of syphilis is heated 

 to 56 for thirty minutes in order that the normal or immune serum 

 complement may be destroyed. The new complement is supplied 

 from normal guinea-pig serum. Before beginning the test it is neces- 



