450 STUDIES IX IMMUNITY. 



much larger quantity of alexinized guinea-pig corpuscles than they 

 in order to exhaust the bovine serum. And we find that bovine 

 serum treated in this manner becomes, if not absolutely inactive, 

 much less active than before treatment. 



In interpreting such experiments it is well to note that heated 

 bovine serum acts in a very small dose. A trace of serum, for ex- 

 ample, 0.01 of a cubic centimeter, on addition to a mixture of 0.5 

 of a cubic centimeter of salt solution, 0.3 of a cubic centimeter of 

 fresh horse serum and 0.05 of a cubic centimeter of guinea-pig corpus- 

 cles, produces distinct conglutination followed by a certain amount 

 of hemolysis. When we consider that bovine serum works in such 

 small doses it is easy to conceive how difficult it is to deprive it 

 entirely of its active substance, the conglutinin. To obtain such 

 distinct results one should use much more blood than do Sachs and 

 Bauer. It is also necessary, particularly in the experiments with 

 bovine corpuscles, that the blood should be sensitized and alexin- 

 ized sufficiently.* 



The details of such an experiment with guinea-pig corpuscles 

 follows : 



In each of two tubes, A and B, is placed 1 c.c. of washed guinea- 

 pig blood. To tube A is added 20 c.c. of salt solution and 6 c.c. of 

 horse serum. An hour later the corpuscles are washed, twice cen- 

 trifugalizcd and the supernatant fluids decanted; 2 c.c. of salt 

 solution plus 0.3 of a cubic centimeter of heated bovine serum is 

 added to each sediment. An hour later the mixtures are centri- 

 fugalized and the supernatant fluids A and B decanted. Another 

 mixture (C) is prepared containing 2 c.c. of salt solution plus 0.3 

 of a cubic centimeter of bovine serum, 56 degrees. 



In three tubes, "a," "b," "c," are placed 1 c.c. of each fluid, A^ 

 B, and C respectively. To each tube there is then added 0.3 of a 

 cubic centimeter of fresh horse serum and 0.05 of a cubic centi- 

 meter of washed guinea-pig blood, and the tubes are placed in the 

 incubator. The result is, that in 8 or 10 minutes "c" and "b" 

 show strong agglutination; there is scarcely visible agglutination in 

 "a' ' in 20 minutes. In a half hour, agglutination, very slight, and 

 hemolysis, scarcely visible in "a," strong agglutination and hemoly- 



* This is proved by the fact that such corpuscles show no agglutination and 

 hemolysis in the mixture of heated bovine serum and horse alexin unless they are 

 strongly sensitized. 



