Resorption of the formed elements 91 



different species, there exist two distinct substances which only dis- 

 solve the red blood corpuscles when they are combined. Here the 

 duality of the haeraolytic agent cannot be doubted, as it may in 

 certain examples of normal serums. Each time that we deprive the 

 serum of a treated animal of its solvent action by heating at 55 

 56 C., this property can be restored to it with certainty by the addi- 

 tion of a little normal serum which, by itself, is incapable of bringing 

 about haemolysis. The heated serum of these injected animals loses 

 the power of dissolving the corresponding red corpuscles, but it re- 

 tains its other acquired property the agglutination of the corpuscles. 

 The red corpuscles, aggregated into voluminous masses quite visible 

 to the naked eye, remain intact indefinitely, if left in the prepared 

 and heated serum. But as soon as we add to them a trace of normal 

 blood (taken from one of a number of species of Vertebrates), the 

 solution of the red corpuscles is not long in taking place. Under 

 these conditions an action of two substances is set up ; one of these 

 substances is found in the heated serum of the injected animal, and 

 the other in unheated normal serum. The first of these substances 

 which not only resists a temperature of 55 56 C., but stands, with- 

 out alteration, heating to 60 65 C., corresponds to the intermediary 

 substance of Ehiiich. By Bordet it has been termed "substance 

 sensibilisatrice 1 ." The second substance, a common one, found in 

 normal serums and destroyed at 55 56 C., is the alexine of Buchner 

 and of Bordet, or the complement of Ehrlich. 



The ease with which one can demonstrate the co-operation of two 

 substances in the haemolysis by the serums of animals treated with 

 the blood of a different species, is due to the fact, that during the 

 course of this treatment the animal organism produces a quantity 

 of an intermediary or sensibilising substance. In fresh animals 

 which have not been treated, it is often very difficult to demonstrate 

 the presence of this substance. Bordet has established the fact that [98] 

 the serum of animals which have been injected several times with the 

 blood of a different species, contains almost the same amount of 

 alexine as does untreated serum. On the other hand, the sensibilising 

 substance makes its appearance in large quantity as the result of 

 these injections. Von Dungern 2 has confirmed this result and con- 



1 Among the synonyms of this substance, resistant to the action of heat, we may 

 mention the following : haemolytic antibody, preventive substance, immunising body 

 (Tmmnnkorper of Ehrlich), amboceptor (Ehrlich), philocytase (Metchnikoff ), desmon 

 (London), copula (P. Miiller). 



2 Miinchen. med. Wchnschr., 1900, S. 677. 



