THE BLOOD. 217 



lumps, and are broken up into granules. This is known as the phe- 

 nomenon of Pfeiffer. This property of the serum of a vaccinated 

 animal is clue to the presence of a substance, a bacteriolysin, or lysin, 

 or cytolysin; the complement arid the intermediary body make up 

 the cytolysin. 



It has been demonstrated that the bacteriolytic cholera-serum 

 contains two distinct substances, acting one after the other in the 

 bacteriolysis, one substance destroyed below 60 C. and existing in 

 normal serum as well as in cholera-serum, and another substance 

 resisting a temperature of 60 C. and not existing except in the 

 cholera-serum. The specific substance has been called a thermostable 

 substance, because it resists a temperature of 60 C. ; and a sen- 

 sitizing substance, because it renders the microbe sensitive to the 

 action of normal serum; also an immunizing substance or mediator, 

 sensitizer, amboceptor, intermediary body, because it exists in the 

 serum of animals immunized against the microbe. The common 

 substance contained in the normal serum has been called a ther- 

 molabile substance, because it is destroyed at 60 C. ; and because 

 it completes the action of immunizing, it is known as a comple- 

 mentary substance, complement, or alexine, or cytase. 



We have seen, in injecting an animal a of species A, that the 

 red blood-corpuscles coming from the animal of another species, 5, 

 will cause a specific agglutinin to appear in the serum of the animal 

 injected, a. But there appears at the same time also a haBmolysin. 

 After having agglutinated the red corpuscles of an animal of the 

 species B, the serum of the animal a dissolves them, or, to speak 

 more exactly, breaks the union of their stroma with their haemo- 

 globin, and the latter passes in solution into the surrounding fluid. 

 It has been shown that ha3molysin is specific and does not act except 

 on the red corpuscles of the species .#, which has served for the 

 preparatory injections. It has been found that haBmolysis, like 

 bacteriolysis, is accomplished in two periods of time; that the 

 haemolysins, like tke bacteriolysins, are formed of two substances, an 

 intermediary body or amboceptor, and a complement or alexin. The 

 specific substance is amboceptor, the alexin is the same common 

 complement or alexin which acts upon the various sensitized bacteria. 

 Take an illustration in which the characters are reversed. We may 

 regard the pepsin in artificial digestion as the amboceptor, and the 

 acid as the complement. The pepsin or amboceptor occurs only in 

 immune serum, while the acid, which may be hydrochloric or phos- 

 phoric, corresponds to the complement found in a variety of serums. 



