310 STUDIES IN IMMUNITY. 



sitized corpuscles to antiserum removes from it the power of pro- 

 tecting additional sensitized corpuscles either of the same or of a 

 different variety. The normal sensitizers in serum B also neu- 

 tralize the antiserum. 



V. The antiserum cures sensitized corpuscles by uniting with 

 the sensitizer that is fixed on them. Corpuscles protected in this 

 way resist alexic activity even when the excess of protective serum 

 has been washed away. 



VI. It would seem as if the complex antisensitizer-sensitizer- 

 red blood cell were broken up on adding normal sensitizers of 

 serum B (i.e., normal serum or immune serum deprived of specific 

 sensitizers by contact with blood cells), because these sensitizers 

 take away at least a part of the antisensitizer that has already been 

 combined with the specific sensitizer. 



VII. The power in normal serum B of inhibiting the curative 

 effect of the antiserum for sensitized corpuscles resists heating 

 to 70 degrees, but not to 100 C. It is not present in aqueous 

 humor from species B. It has previously been ascertained that 

 the aqueous humor of vaccinated animals contains no specific sen- 

 sitizer. 



VIII. When antiserum affects the sensitizer attached to red 

 blood cells it removes from the complex the property of fixing alexin. 



IX. The identity of the antibodies of normal and of immune 

 serum affecting the same cell, as assumed by certain writers, must 

 be considered as not proved. 



X. Ehrlich's theory, which supposes that specific antibodies 

 are identical with the cell receptors that combine with those sub- 

 stances against which the animal becomes immunized, is erroneous. 

 The arguments to support this theory obtained from the study of 

 antisensitizers are not sound. The thesis that a given hemolytic 

 immune serum contains several separate specific sensitizers has no 

 experimental justification. The conception of complement devia- 

 tion due to an excess of sensitizer is purely hypothetical. 



XL The short duration of the passive immunity afforded by 

 injecting an immune serum from an alien species would seem to be 

 due to the fact that the recipient generally elaborates an antago- 

 nistic substance. The effect of this substance is not directed 

 especially against the antibody that gives immunity, but in a 



