264 



COLLECTED STUDIES IN IMMUNITY. 



of serum and then determining the amount of anticomplement 

 required in each case. In one of the experiments we made a parallel 

 test with a large excess of amboceptors. The results showed that 

 under these circumstances, for each of the cases and with a certain 

 amount of amboceptor, the anticomplement required is proportionate 

 to the amount of complement. This is shown in Table IX. 



TABLE IX. 



1 cc. 5% SHEEP BLOOD + AMBOCEPTOR OF GOATS IMMUNIZED WITH SHEEP 



BLOOD + GTTINEA-PIG SERUM AS COMPLEMENT. 

 The serum of a goat treated with rabbit serum, as anticomplement. 



Amount of 

 Amboceptor. 



Amount of 

 Complement. 



Amount of 

 Anticomplement 

 Necessary for Com- 

 plete Neutralization. 



Little Amboceptor ( = 1 Amboceptor Unit). 



0.005 

 0.005 



0.1 

 0.2 



0.22 

 0.4 



B. Much A mboceptor ( = 25 .4 mboceptor Units) . 



0.125 

 0.125 

 0.125 



0.006 

 0.012 

 0.024 



0.24 

 0.42 

 0.8 



1 cc. 5% Ox BLOOD + AMBOCEPTOR OF A GOAT IMMUNIZED WITH Ox BLOOD + 



RABBIT SERUM AS COMPLEMENT. 

 The serum of a goat treated with rabbit serum as anticomplement. 



* = about 2 amboceptor units. 



Here, then, we are dealing with the same phenomenon which in 

 the domain of antitoxin immunity w r e know as the multiplication of 

 the I/o dose. From our standpoint this is easily explained, for if 

 at any point in the saturation of the blood-cells' amboceptors a 

 certain amount of the complement dominant in this case is neutral- 

 ized by a certain quantity of anticomplement, the other conditions 

 will in no way be altered by a doubling, quadrupling, etc., of the 



