562 MICROBIOLOGY OF THE DISEASES OF MAN AND ANIMALS. 



body cells takes place. On the other hand should the animal, such as a 

 rabbit or man, possess the necessary complement, as they do, lysis will 

 take place. 



Substances are sometimes present normally in sera which have the 

 power of combining with the amboceptors which may be present, and in 

 turn prevent the latter from combining with the cells so that when the 

 complement is added there will be no lysis. Such substances must be 

 designated as antiamboceptors. These antiamboceptors may be developed 

 in an animal by immunization with amboceptors of definite kinds (antianti- 

 bodies). There are other substances which may also engage the ambo- 

 ceptors which cannot be called amboceptors in the true sense, but they 

 accomplish the same purpose and are therefore classed with these bodies. 



The Deviation of the Complement. The complement may be deviated 

 in several ways and as a result lysis of the cells in question may be 

 prevented. 



Occasionally there is noted in sera normally substances which may 

 combine with the complement and prevent this body from combining with 

 the amboceptor. Such substances are anticomplements and may be pro- 

 duced 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 complement it may be deviated. In 

 this case the cells will have taken up all the possible amboceptor and there 

 will be an abundance of amboceptor free in the serum. It has been dem- 

 onstrated that complement will combine with free amboceptor before it 

 will combine with bound amboceptor. In this case all the available 

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

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

 fections where the development of bacteriolytic substances is of importance 

 and necessary in effecting a recovery. The infectious microorganisms 

 may not be destroyed for the above reason. 



The Fixation 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 recently 

 devised test for syphilis which is briefly stated as follows: when the 

 ysphilitic antigen is combined with the supposed amboceptor in the blood 



