602 COLLECTED STUDIES IN IMMUNITY. 



the second of these two alternatives would at once explain the 

 specific action of the antilysins. On the other hand, it is difficult 

 to reconcile it with the findings of Pfeiffer and Friedberger, namely, 

 "that it is possible, out of a mixture of inhibiting serum and immune 

 serum, to extract the amboceptor by the subsequent addition 

 of bacteria." While thus compelled to leave open the interpreta- 

 tion of the results reported by Pfeiffer and Friedberger, we should 

 like to report on analogous findings which we encountered with 

 haBinolytic sera in the course of experiments made to check up 

 Pfeiffer and Friedberger's results. Owing to greater ease with 

 which test-tube experiments can be controlled, these experiments 

 proved more susceptible to analysis. The bloods employed were 

 from sheep and pig, and these were haemolyzed by the correspond- 

 ing immune sera l with guinea pig serum as complement. 



Neither combination is inhibited by inactive normal rabbit 

 serum, and yet, as soon as this serum is digested with sheep blood 

 or with pig blood, it is found to have acquired antilytic properties. 

 This inhibition of hamolysis, moreover, is specific, so that when 

 sheep blood-cells have been used for treating the serum, the inhibi- 

 tion extends only to the haemolysis of sheep blood, but not to that 

 of pig blood, and when pig bloocl is used, the inhibition applies 

 only to pig bloocl hamolysis. 



This is illustrated by the following experiment: To 10 cc. inactive 

 rabbit serum were added the sedimented c^lls from 10 cc. sheep 

 (or pig) blood; the mixture was kept at 37 C. for one hour, and 

 then centrigufed to separate the serum from the blood-cells. The 

 supernatant fluids thus obtained were added in decreasing amounts 

 to constant quantities (0.1) of active guinea-pig serum, and digested 

 for half an hour; then 1 cc. of a 5% suspension of blood and a suitable 

 amount (1^ amboceptor units) of amboceptor was added. Native 

 rabbit serum was treated in exactly the same manner as the super- 

 natant fluids. 



The following table shows the degree of solution noted in the 

 different combinations. The tubes in Column A contained sheep 

 blood plus 0.01 cc. of the corresponding immune serum; the tubes 



1 The immune serum for the pig blood was obtained by immunizing a rabbit 

 with pig blood; that for sheep blood was obtained by immunizing a rabbit 

 with ox blood, as this was found by Ehrlich and Morgenroth (Berlin, klin. 

 Wochen., 1901, Nos. 21 and 22) to be haemolytic also for sheep blood. 



