152 HAEMOLYSIS COMPLEMENT 



studies on the alexins, assumed that the serum of each animal 

 contained one alexin, though the alexins of different animal 

 species were different. This view was also held by Bordet and 

 others, and constitutes the " Unitarian " view of alexin or com- 

 plement. Metchnikoff holds that there are two alexins, or, as he 

 calls them, cytases macrocytase, which acts specially on red 

 blood-corpuscles, cells, etc., and is joined by the large mononuclear 

 cells ; and microcytase, which acts on bacteria, and is formed by the 

 polynuclear leucocytes. 



As against these views, Ehrlich advances the theory of the 

 multiplicity of the complements, the proof of which appears entirely 

 satisfactory. According to him there are numerous complements 

 in the serum of every animal, and these differ from one another in 

 their haptophore groups, so that one can reactivate one ambo- 



* # 



FIG. 33. SHOWING SOME OF THE CONSTITUENTS WHICH CAN BE DEMON- 

 STRATED IN THE SERUM OF A GOAT WHICH HAS BEEN INJECTED WITH 

 SHEEP'S CORPUSCLES. 



ci, b, and c are the different complements, a' , b' , and c' the amboceptors which 

 unite them to the corpuscles of the sheep (A), rabbit (B), and guinea pig (C). 



ceptor, another another. They differ in some cases in other 

 respects. The first example which he was able to adduce in 

 which there were at least two complements in a sample of serum 

 was that of a goat which had been injected with sheep's corpuscles, 

 and which dissolved those of the sheep, guinea-pig, and rabbit. 

 But when this serum was heated to 56 C. for three-quarters of an 

 hour, it was found to have no action on the corpuscles of the latter 

 animals, whilst that of the former was unchanged. Evidently 

 then, the complement which activated the amboceptor combining 

 with the sheep's corpuscles was thermostable ; that acting on the 

 others, thermolabile. This was the first known example of a 

 thermostable complement. In a later experiment he was able to 

 prove that the complements taking part in the haemolysis of 

 rabbit's corpuscles and that taking part in the solution of guinea- 

 pigs were different : the latter passes through a Pukall's filter, 

 the former does not. 



