176 STUDIES IN IMMUNITY. 



red blood cells. As a matter of fact, Camus and Gley and Kossel 

 have shown that in the serum of animals immunized against eel 

 serum there are substances that protect their corpuscles against the 

 dissolving effect of this toxic serum. 



In order to make such results evident the " toxin" employed 

 should be powerful. Animals of species A should be injected with 

 serum or defibrinated blood of species B, and the serum of species B 

 should be able to agglutinate and dissolve the red blood corpuscles 

 of species A energetically. The rabbit and the hen fulfill these 

 conditions: the agglutinating and dissolving effect of normal hen 

 serum on rabbit corpuscles being very energetic. The antihematic 

 property of rabbit serum for guinea-pig corpuscles, on the contrary, 

 is only slight; and therefore the serum of a guinea-pig vaccinated 

 against rabbit blood is not suited to the study of this antitoxic or 

 antihemotoxic property. 



Normal hen serum agglutinates an equal amount of defibrinated 

 rabbit blood energetically. Two or three parts of this serum will 

 dissolve one part of rabbit blood corpuscles. Rabbits that have 

 received intraperitoneally three injections of 10 c.c. each of hen 

 blood have an antitoxic property in their serum, although it is not 

 very intense. It may be demonstrated in a mixture containing 

 normal rabbit blood, hen serum (fresh) and active rabbit serum; 

 and, as a control, normal rabbit blood, fresh hen serum and normal 

 rabbit serum. The exact proportions in these tubes are as follows: 



Tube A, one part of normal rabbit blood; three parts of hen 

 serum ; ten parts of active rabbit serum. 



Tube B, one part of normal rabbit blood; three parts of hen 

 serum; ten parts of normal rabbit serum. In the second of these 

 tubes the rabbit blood corpuscles rapidly collect into thick compact 

 masses that after two or three hours hemolyze. In tube "A" the 

 corpuscles remain indefinitely intact and only a slight agglutination 

 in very small clumps is evident. In addition to a property of pre- 

 venting the dissolution of corpuscles the active serum has a distinct 

 anti-agglutinating property. 



The control mixture "B" shows that normal rabbit serum has no 

 antitoxic properties. 



If the amount of active serum is diminished to any extent or the 

 amount of dissolving hen serum is increased, the antitoxic effect 



