614 COLLECTED STUDIES IN IMMUNITY. 



entirely to that of Gay's immune serruin. The complete solvent 

 dose of normal rabbit serum fluctuates in most instances between 

 0.25 and 0.1 cc. The solvent dose of Gay's immune serum was 

 0.2 cc. The quantity employed by Gay, 0.4 cc., probably suffices 

 with any rabbit serum to completely dissolve Ice. 5% sheep blood 

 on the addition of 0.1 cc. guinea-pig serum. Hence it is not at all 

 impossible that Gay employed a serum which contained no immune 

 amboceptors whatever, and represented merely an albumin anti- 

 serum. If amboceptors were artificially produced, they were 

 certainly present in so small concentration as to be unable to in- 

 crease the action of the normal amboceptors to any appreciable 

 degree. In my paper, however, I distinctly stated that the inhibit- 

 ing sera obtained by treatment with blood-cells acted only against 

 haeomlysis produced by immune amboceptors, and that this anti- 

 lytic action was prevented by the action of the normal amboceptors. 

 Just this constituted my explanation for the absence of the inhibit- 

 ing function in native serum, for I assumed that the inhibiting 

 antibodies were already present in native rabbit serum and were 

 merely hidden by the simultaneous action of the specific normal 

 amboceptors. 



Gay's experiments thus constitute an involuntary complete con- 

 fimation of my views, and it is to be regretted that Gay has allowed 

 himself to be so misled in the interpretation of my experiments. The 

 incorrectness of his views should have struck him from a number 

 of statements in my first paper. If his idea was correct it follows 

 that the inhibiting action should appear in every rabbit serum 

 treated with insufficiently washed sheep or ox blood. I distinctly 

 stated, however, that I could only then demonstrate an inhibiting 

 effect through absorption with blood-cells when the serum under 

 examination from the outset contained amboceptors for the species 

 of blood in question. I said particularly that normal rabbit serum, 

 which contains no amboceptors for ox blood, is in no wise changed 

 by absorption with ox blood, i.e., it neither before nor after treatment 

 with ox blood does it inhibit haemolysis of sheep blood by immune 

 serum, while on the haemolysis of ox blood it exerts the same inhibit- 

 ing power before and after treatment. Finally I called attention 

 to a number of rabbit sera in which, quite exceptionally, the ambo- 

 ceptors for sheep blood were absent. These sera from the outset 

 were antilytic for the haemolysis of sheep blood, and they remained 

 so in unaltered degree after digestion with sheep blood. After 



