26 COLLECTED STUDIES IN IMMUNITY. 



mination will be of the highest interest. To be sure the study of 

 this question offers considerable difficulties, difficulties through 

 which previous experiments in this direction have been brought 

 to naught. (Belfanti and Carbone, Bordet.) 



We have from the beginning maintained that it is possible to 

 gain an insight into these processes, only when any changes occurring 

 in the serum are determined by means of frequent and progressive 

 examinations. Small laboratory animals, because of the amount 

 of blood required for these continuous examinations, are therefore 

 unavailable, and hence we selected goats as being best adapted for 

 these experiments. 



After it had been determined that a single injection of a large 

 amount of blood sufficed to produce the specific hasmolytic sub- 

 stances in the serum, we usually injected our animals once with a 

 large amount of goat-blood. (800-900 cc. for a goat of 35-40 kg.) 

 In order to overwhelm the body as rapidly as possible with the con- 

 stituents of the blood-cells, we made use of intraperitoneal injections. 

 For .the same reason we thought it best not to inject intact blood- 

 corpuscles, but to inject blood which had been made laky by the 

 addition of water. We argued that blood-cells of the same species 

 as the animal injected would be destroyed very slowly in the peri- 

 toneal cavity of this animal, and that consequently the absorption 

 would be so gradual as to prevent the occurrence of what may be 

 termed an " ictus immunisatorius." From the second or third 

 day on, we withdrew samples of serum from the animals so treated, 

 and tested the solvent action on the blood of numerous other goats. 

 Our method generally was first to determine whether any indica- 

 tions of hsemolytic action were present. For this purpose a drop 

 of normal goat blood was allowed to fall into undiluted serum of 

 the treated goats, and the occurrence of any red coloration looked 

 for. If this test was positive, we proceeded to test the hsemolysin 

 in the usual manner by adding decreasing amounts of this serum 

 to tubes containing 1 cc. of a 5% mixture of goat-blood in 0.85% 

 salt solution. 



. With these preliminary remarks we proceed to our first posi- 

 tive test (February 16, 1900). The subject of this was a strong 

 male goat, buck A, weighing 33.5 kg., into whom there were injected 

 intraperitoneally 920 cc. goat-blood (mixed from the blood of goats 

 1, 2, and 3) made laky by the addition of 750 cc. water. From the 

 second day on, small amounts of blood were withdrawn daily for 



