270 IMMUNOLOGICAL METHODS OF DIAGNOSIS 



with a single cholera agar culture that has been killed by exposure 

 for one hour to a temperature of 56 C. Two weeks later the animals 

 are bled to death, the sera mixed, evaporated in a vacuum, and the 

 dry residue is put up in portions of 0.1 or 0.2 gram, in glass beads, 

 which are then sealed. The titer of this preparation must be ascer- 

 tained before use; it usually corresponds to about 0.0005 milligram 

 as calculated for the liquid serum. 



In lieu of the bacteriolytic test in vivo, as outlined above, Stern 

 and Korte have proposed a corresponding method of examination 

 in vitro, for a consideration of which the reader is referred to 

 special works. 



DIAGNOSTIC REACTIONS DEPENDING UPON COMPLEMENT 



FIXATION 



When reaction products of amboceptor character are brought 

 together with their corresponding antigens in the presence of com- 

 plement, an interaction takes place between the two first mentioned 

 bodies, in consequence of which complement is bound. This can be 

 demonstrated by the subsequent addition of washed red corpuscles, 



FIG. 16 



10 < < 10 



Complement 



Antigen Syphilitic 



Amboceptor 



Red blood Hemolytic 



Corpuscles .Amboceptor 



Schema illustrating the principle of the Wassermann reaction. 



and a corresponding hemolytic amboceptor, when hemolysis will either 

 not occur at all, or does so only to a limited extent, according to the 

 degree to which the available quantity of complement has been bound. 

 The exact outcome of the reaction will, of course, depend upon 

 quantitative conditions. If we suppose that the interaction between 



