STUDIES ON AXTIAMBOCEPTORS. 



655 



with the antiserum, the rabbit amboceptor being added to the mixture only 

 after the antiamboceptor has been removed. The result of this experiment 

 is shown in the following table (Column A of Table I may be regarded as the 



control) : 



TABLE II. 



It will be seen that with this modification, too, the antiserum,. 

 except in very large amounts, does not influence haemolysis. There 

 can be be no doubt, therefore, that the inhibiting factor of the anti- 

 serum under these conditions is practically only the antiamboceptor. 

 While these experiments positively demonstrate the existence of 

 antiamboceptors in the antiserum, they leave untouched the question 

 as to whether the antiserum may not at the same time contain 

 antibodies for albuminous substances. Considering the manner in 

 which the antiserum is produced, it is natural to assume that such 

 antibodies are formed along with the antiamboceptors. All that we 

 are interested in at the present time, however, is the possibility of 

 these antibodies counterfeiting the existence of antiamboceptors. 

 After the experiments just described, this seems out of the question. 



It might be doubted whether the albumin content of the normal 

 rabbit serum corresponds to that of the rabbit serum specific for 

 ox blood. The immune serum might be much richer in albuminous 

 substances. Although there seems little basis for such an assumption, 

 we have thought it advisable to investigate the matter. In a further 

 experiment, therefore, we used varying quantities of the normal 

 rabbit serum with constant amounts of the antiserum. The ex- 

 periments were carried out as follows: 



Two series of tests are made: 



(A) Each tube contains 0.15 cc. antiserum, plus 0.0015 cc. rabbit ambo- 

 ceptor, plus decreasing amounts inactive normal rabbit serum. After standing 



