STUDIES ON H.EMOLYSINS. 



95 



This variable ratio indicates that the solvent action on the two 

 species of blood-cells is not the simple function of one and the same 

 immune body, but that two fractions of immune bodies are pres- 

 ent in the serum, of which one acts exclusively on ox blood-cells, 

 while the other fraction acts both on ox blood and on goat blood- 

 cells. 



These relations can be studied directly by means of elective ab- 

 sorption. If the immune body is treated with a sufficient amount of 

 ox blood cells and the fluid is then separated by centrifuge, it will 

 be found that the serum has lost its solvent action for both species 



FIG. 1. 



' >C 



Ox 



Goat 



Blood-cell of an ox and of a goat, showing specific and common receptors 



of blood; for by means of the ox blood-cells, which as the original 

 excitants of the immunity are carriers of all the receptors in question, 

 both fractions of immune body have been bound. When the same 

 experiment is performed with goat blood-cells, it can be shown that 

 the fluid Aas lost its solvent power for goat blood, while that for ox blood 

 remains. In favorable cases 'the solvent power for ox blood may 

 remain almost unchanged. The conditions present can be readily 

 understood by reference to Fig. 1. 



Let this represent schematically three portions of the combin- 

 ing groups of the blood-cells, of which the first, a, is present only in 



