STUDIES ON H^MOLYSINS. 69 



inactivated the immune serum and determined the minimal amount 

 of the inactive serum which would cause complete solution in the 

 presence of (1) normal rabbit serum, or (2) of guinea-pig serum. 

 We found that it required 0.25 cc. of the inactive immune serum to 

 effect complete solution of the given amount of rabbit blood when 

 rabbit complement was employed, whereas only 0.025 cc. of the immune 

 serum was required when guinea-pig complement was employed. 



This result, however, cannot be harmonized with Bordet 's theory of 

 sensitization. According to his view one would expect that a blood- 

 cell which is sensitized by the presence of the immune body is subject 

 equally to the action of various alexins. In both cases the same 

 amount of immune body should then suffice to make the blood-cells 

 sensitive to the alexins (complements). As a matter of fact, how- 

 ever, it requires ten times as much in the one case as in the other. 

 If one desired to hold to Bordet 's theory one might possibly say that it 

 requires ten times as strong a sensitization with the same immune body 

 in order to make the cells sensitive to the alexin of rabbit serum. 



If this highly complicated assumption w r ere correct, the relation 

 as above determined, 1 : 10, should represent a constant ratio. Owing 

 to a lack of animal material we were unable to study this question 

 of constant ratio on the example selected by Bordet. However, 

 in an analogous series of cases for which we had abundant material, 

 we were able to pursue this question further. 



We made use of a goat which had been treated with sheep blood 

 and whose serum therefore dissolved sheep blood-cells. The inac- 

 tivated serum of this goat could be reactivated by two complements, 

 that of normal goat serum and that of horse serum. The anticom- 

 plement obtained by treating a goat with horse serum inhibited, 

 even in small amounts, the action of the horse complement; whereas 

 its action on the goat complement was so slight as to be practically 

 negligible. The conditions here, therefore, are exactly the same 

 as in the case described by Bordet. 



In the beginning of the observations it was found that 1 cc. of 

 a 5% mixture of sheep-blood, mixed with normal horse serum to 

 serve as complement, was completely dissolved on the addition of 

 0.35 cc. immune body (inactivated immune serum); whereas when 

 normal goat serum was used as complement only 0.025 cc. of the 

 immune body was required. This corresponds to a ratio of 14 : 1. 

 On repeating the test a week later with serum freshly drawn from 

 the immunized goat we found that the constituents which were 



