STUDIES ON H/EMOLYSINS. 101 



spasmin or for sausage poison. Within the animal organism, in like 

 manner, certain receptors are evidently widely distributed in the 

 most varied organs, as is shown, for example, by the experiments 

 with tetanus poison. Looked at from this standpoint, the apparent 

 deviations in specificity are comprehensible. We are convinced 

 that in this field the near future will furnish us with extensive ma- 

 terial of immense value in the analysis and study of the distribution 

 of receptors. We are led to conclude, therefore, that in the produc- 

 tion of immune bodies by immunizing with cells w r e can speak of 

 specificity only in the sense that there is always a specific relation 

 between the separate types of immune bodies and the receptors. 



The foregoing experiments constitute conclusive proof of the 

 plurality of the immune bodies produced by injections of ox 

 blood and goat blood. We next endeavored to extend these results 

 by effecting a differentiation of various groups of immune bodies 

 by means of the anti-immune bodies. 1 The highest concentration of 

 immune bodies at our disposal was the serum of a rabbit which had 

 been immunized with ox blood. For various reasons we chose goats 

 for these immunizing experiments, for we knew that their blood- 

 cells already contained receptors capable of binding a portion of the 

 mixed immune bodies. In treating these goats we used the inactive 

 serum of a rabbit immunized with ox blood. This serum, which 

 was of the highest possible strength, was injected subcutaneously. 

 During the course of two months we had thus injected 120 cc. of 

 an immune body serum, of w r hich 0.005 cc. sufficed, when reactivated 

 with guinea-pig serum, to completely dissolve 1 cc. of a 5% mixture 

 of ox blood-cells. At the end of that time we were able to demon- 

 strate the existence of an anti-immune body of considerable pro- 

 tective power. That this was really an anti-immune body which 

 inhibited the anchoring of the immune body to the red blood-cells, 

 is seen by the following combining experiment. 



0.5 cc. of the anti-immune body (inactive serum of a goat treated 

 as just described) are mixed with varying amounts of the immune 

 body (inactive serum) of a rabbit treated with ox blood. Thereupon 

 1 cc. of a 5% mixture of blood-cells is added to each specimen. These 

 are then kept at 40 C C. for one hour and centrifuged. The various 

 sediments are then mixed with salt solution and 0.15 cc. normal 

 guinea-pig serum. A parallel experiment (control test) is made in 

 1 See Ehrlich's recent study, page 573. 



