IMMUNIZING EXPERIMENTS WITH ERYTHROCYTES. 161 



plement present in the serum, causing serious symptoms or, with larger 

 amounts of blood, fatal results. This accords with the phenomena 

 observed by Rehns 1 when he injected rabbits which had been immu- 

 nized with ox blood, intravenously with normal ox blood. Only two of 

 the animals I employed, namely those injected with 7-8 cc. blood, re- 

 mained alive sufficiently long. In one of these only traces of immune 

 body were found in the serum, whereas the serum of the other animal 

 effected complete solution in doses of 0.05 cc. In the serum of a 

 control animal the limit of complete solution was 0.01 cc. These 

 few experiments confirm the results obtained with intraperitoneal 

 injections, that blood-cells saturated with immune body have not by any 

 means always lost the power to excite a certain degree of immunity reaction 

 in the organism. 



Our results, therefore, show that in half of the animals, in con- 

 formity with the results obtained by von Dungern, the power of the 

 blood to cause an immunity reaction is lost, owing to the blocking of 

 that particular group in the blood-cell which unites with the immune 

 body. In the remaining cases, however, the specific immune body 

 was produced, though always in decidedly less amount, since only 

 a fifth to a tenth part of the amount appeared that was produced by 

 the control animals. This apparently unfavorable portion of the ex- 

 periment shows at least that saturation with immune body exerts a marked 

 restricting influence. These results agree with those obtained by 

 Neisser and Lubowski with injections of agglutinated typhoid bacilli. 



Furthermore, like Neisser and Lubowski, in an animal which had 

 not reacted to the injection of saturated blood, we found after injec- 

 tion of the same amount of normal blood that an immune body of 

 considerable power had developed in the serum. The complete 

 solvent dose for 1 cc. 5% ox blood amounted to 0.005 cc. serum These 

 last experiments, which have been done on a much larger scale by 

 Neisser and Lubowski on typhoid bacilli, indicate that the failure of 

 antibodies to form is not due to possible individual differences in the 

 reacting capacity of the organism. Considering the uniform appear- 

 ance of immune body in rabbits treated with ox blood such an assump- 

 tion would have lacked all probability. 



That portion of the experiments in which the injection of saturated 

 blood-cells was borne by the animals without producing any reaction, 

 can be regarded, as has been done by von Dungern, as a complete demon- 



1 Rehns, Comp. rend de la Soc. biol., 1891, No. 12. 



