24 PROPERTIES OF H^MOLYTIC SERA 



have been kept for some time in the dry condition. 

 Furthermore, if washed red corpuscles be heated for twenty- 

 four hours at 55 C. and then their absorptive properties 

 for complement be tested, it is found that quite an appre- 

 ciable amount of the latter enters into combination. The 

 following facts may be stated regarding this direct union of 

 complement. 



1. The combination is a firm one and I have been unable 

 to recover the complement after it has been taken up. The 

 test is made by washing in normal salt solution the cells, 

 &c., which have taken up complement, to rid them of free 

 complement, and then bringing them into intimate contact 

 with red corpuscles treated with immune-body, the mixture 

 being exposed for the usual time at 37 C. No haemolysis 

 occurs. 



2. When the cells, &c., which have taken up complement 

 are exposed to a temperature sufficient to destroy free 

 complement i. e. 55 C. or rather sufficient to deprive 

 complement of its characteristic property, the affinity for 

 complement is not restored. This may be interpreted in 

 accordance with Ehrlich's views on the constitution of com- 

 plement, according to which it possesses a labile zymotoxic 

 group and a more stable haptophorous group. The action 

 of heat destroys the zymophorous group though apparently 

 not the haptophorous (vide section on complementoids). 

 The result which has been stated as to the effect of heating 

 on the combined complement shows that the latter, when 

 presumably it is altered by heat, is not displaced by normal 

 complement. 



3. The direct union of complement with cells, &c,, takes 

 place most rapidly about 37 C., whereas at C. practically 

 no combination occurs. This can be readily tested by 

 the usual methods. In this respect the direct union of 

 complement corresponds with the union through the inter- 

 vention of immune-body. 



