612 COLLECTED STUDIES IN IMMUNITY. 



serum simply does not contain the antibodies (precipitings) acting 

 on the sheep serum, and this is why there is no inhibition. In 

 one experiment, however, I called attention to the fact that the 

 haemolysis of blood cells sensitized only with immune serum is 

 prevented by the inhibiting serum, whereas blood-cells sensitized 

 with immune serum and then also with normal serum are dissolved 

 under these conditions. In both cases after the amboceptors had 

 been anchored I separated the serum fluid by centrifuging, It 

 so happened that I expressed myself somewhat differently in the 

 second case, and this has led to a misconception. In the second 

 case I said "the blood-cells were digested with serum and then 

 freed from serum fluid by centrifuging " ; in the first case I merely 

 said "the reagent used was sheep blood sensitized with immune 

 serum." By "sensitized blood," of course, I mean blood-cells 

 which, after treatment with amboceptors, are separated by centrifuge. 

 In fact, in another experiment contained in this study I expressly 

 state "sheep blood +immune serum." However, I am willing to 

 admit that my mode of expression might give rise to doubts. Gay, 

 however, seems to know my experimental technique better than 

 even I myself. He declares simply that I had centrifuged in the 

 second case, i.e., had removed the precipitating portion of the 

 immune serum, and had not done so in the first case. My experi- 

 ments therefore contained " a grave experimental error." Through 

 his own experiments, Gay believes to have furnished "a complete 

 refutation of Sach's hypothesis." 



Gay has made a regrettable mistake. Moreover, in repeating 

 my experiments he has allowed a grave error to creep into his own 

 technique. It really is immaterial, in my experiments, whether the 

 immune serum is centrifuged from the blood-cells or not, since the 

 immune serum I employ has so high an amboceptor content that the 

 quantity used for sensitizing (0.002 cc.) is only about 1-200 of that 

 employed by Gay. According to my experience, this quantity is 

 too small to effect a precipitation or sensitization of the albuminous 

 bodies of the serum. Nevertheless I have made a number of exper- 

 iments with my immune serum according to the procedure outlined 

 by Gay. I treated rabbit serum with sheep blood washed once, 

 and also with sheep blood washed five times. Both lots of serum 

 so treated proved equally antihaemolytic, whereas native rabbit 

 serum possessed no inhibiting action whatever. This is illustrated 

 by the following protocol. 



