86 PKOPERTIES OF H^MOLYTIC SERA 



generally, would go to show that even if some substance 

 should appear which acted as an immune-body, there is a 

 further provision whereby the complement of an animal 

 should produce comparatively little harmful effect. 



ON THE ACTION OF COMPLEMENT AS 

 AGGLUTININ 



In the course of our experiments on haemolytic sera we 

 have met with the following phenomenon which appears of 

 some interest. It consists in the agglutination of the 

 corpuscles of an animal by its own complement through 

 the medium of the corresponding immune-body derived 

 from another animal, and was observed first in the case of 

 ox's corpuscles, the immune-body used being obtained 

 from the rabbit. The fundamental fact is that if a certain 

 amount of immune-body and ox's complement be added 

 to ox's corpuscles, scarcely any lysis of the corpuscles occurs, 

 but they become agglutinated into large masses which cannot 

 be dissociated by shaking. The immune-serum from the 

 rabbit contains some agglutinin, but the degree of agglutina- 

 tion produced by this is quite trifling compared with that 

 seen when complement also is added. There is thus no doubt 

 that the agglutination phenomenon depends on the co-opera- 

 tion of two substances in a manner comparable to what 

 obtains in lysis. The following are the chief facts regarding 

 the conditions of occurrence of the agglutination and the 

 nature of the agglutinating substance in the ox's serum. 



Firstly as regards dosage, a certain amount both of com- 

 plement and immune-body is necessary. Taking as the 

 standard (one haemolytic dose) the amount of immune-body 

 sufficient to produce complete lysis of 1 c.c. of 5 per cent, 

 suspension of ox's corpuscles in 0-8 per cent, sodium chloride 

 solution along with guinea-pig's complement, we find that 

 the maximum agglutination is obtained by 3-4 doses of 



