434 



THE TECHNIC OF COMPLEMENT-FIXATION REACTIONS 



Furthermore, serums that are sterile and are kept for some time at 

 room temperature or even in an ice-chest acquire an anticomplementary 

 power that is destroyed by heating at 55 C. for half an hour. Therefore 

 when serums are preserved for a number of days they are heated not so 

 much for the purpose of removing native hemolytic complement, which 

 has probably already deteriorated, but to remove thermolabile anti- 

 complement. Serums that are old or contaminated with bacteria are likely 

 to be highly anticomplementary, and this property cannot be destroyed 



mimmmm ' 



FIG. 109. OUTFIT FOR COLLECTING BLOOD FOR THE WASSERMANN REACTION (NEW 



YORK BOARD OF HEALTH). 



The container is a centrifuge tube which holds about 15 to 18 c.c. of blood to the 

 mark. The needle is furnished in a separate tube, sterilized and ready for use. This 

 outfit is not adapted for mailing. 



< 

 by heating at 55 C. or filtration through a Berkefeld filter. In order to 



conduct a reliable test it is usually necessary to secure fresh serum. 

 This anticomplementary action of serums is so important that in every 

 complement-fixation test there is a serum control tube containing all the 

 ingredients except antigen, the object being to discover any inhibitory action 

 of the serum itself upon the complement. 



Wechselmann's method of converting syphilitic serums showing a 

 negative or weakly positive reaction to those exhibiting a marked positive 



