The normal variation in the antitryptic index is very marked in any particular rabbit, and is even greater in different animals.
An unmistakable rise in the antitryptic index has been produced in at least two of the six rabbits immunized against trypsin.
The progress of immune body production against trypsin is very peculiar, in that at first there is a marked fall in the antitrypsin, followed soon, however, by rather a sudden rise which is at best only 300 per cent above the normal variation. At this level the antibody content remains approximately stationary for a comparatively brief period and is then supervened by a rapid return to the normal, in spite of continued periodical injections of trypsin.
Immunity to pancreas trypsin appears to cause no change in the protein quotient. This fact may serve as additional evidence in favor of the recently emphasized view that immunity is non-dependent on the concentration of the serum proteins.