JOINT ACTION OF SEVERAL AMBOCEPTORS. 627 



a certain point. The portion bound, to be sure, is not inconsider- 

 able. It is to be noted, however, that horse serum treated with 

 guinea-pig blood at loses practically none of its power to effect 

 haemolysis in conjunction with inactive ox serum. According 

 to Bordet and Gay's conception, provided that any considerable 

 quantity of amboceptor had been bound, this should not be the 

 case, for in the opinion of these authors the horse serum plays the 

 role of amboceptor in the haemolysis. A decrease in the quantity 

 of amboceptor should, of course, manifest itself by a reduction 

 in the hsemolytic power. It might be objected that the ambo- 

 ceptor in horse serum exists in excess, and that therefore it was 

 entirely irrelevant whether a portion was present or absent. This 

 objection, however, can be tested experimentally. Suppose, for 

 example, that the horse serum digested at with guinea-pig blood, 

 still contained enough amboceptor to produce, in conjunction 

 with inactive ox serum, the full hsemolytic effect as conceived by 

 Bordet and Gay. It is obvious that when such a serum is subse- 

 quently treated with guinea-pig blood at 37 the impairment in 

 the ability to bring about hsemolytic effects should be as great or 

 even greater than that produced in native horse serum. The 

 experiment, however, shows that just the contrary is the case. The 

 conditions are really reflected in Table 2 of Browning's paper. 

 We shall, however, reproduce the result of an analogous experiment. 



Three series of tubes are prepared, each containing 1 cc. 5% guinea-pig 

 blood and decreasing amounts of horse serum diluted with the same amount 

 of physiological salt solution. The total volume in each tube is 2 cc. 



The tubes of series A are kept at 37 for 1^ hours and then centrifuged. 

 The supernatant fluids thus obtained are then digested with the sediments 

 from 1 cc. 5% guinea-pig blood plus 0.3 cc. inactive ox serum. 



The tubes of series B are centrifuged after having been kept at for two 

 hours. The supernatant fluids are treated as is series A. 



The tubes of series C are centrifuged after having been kept at for two 

 hours. The supernatant fluids are digested for two hours at 37 with the sedi- 

 ments from 1 cc. 5% guinea-pig blood. After again centrifuging, the super- 

 natant fluids are treated with the sediments from 1 cc. 5% guinea-pig blood 

 plus 0.3 cc. inactive ox serum. 



The result is shown in Table VI. 



The horse serum which underwent a preliminary treatment 

 at is thus seen to have lost but little of its power to bring about 

 haemolysis, by the subsequent digestion at 37. Certainly the 

 reduction is considerably less than that produced by the direct 



