Rather more than a year since, Warfield1 claimed the discovery of a new enzyme in human saliva, ``a substance which has the power to split glycyltryptophan'' (a dipeptid). This hydrolyzing property of saliva was stated as being lost when saliva is acid or when heated to 100 C. Warfield's report bases his conclusions on the action on glycyltryptophan of twenty-eight specimens of saliva. Of this number, saliva was alkaline (where stated) in all the positive reactions and acid in all negative glycyltryptophan tests. The use of tobacco, observed in seven instances, did not materially alter the result so long as the salivas remained alkaline.
About six months after Warfield's communication, Weinstein,2 in writing of the ``tryptophan'' test for carcinoma ventriculi, confirmed Warfield's findings. Weinstein's observations are indefinitely stated. The few experiments actually quoted admit of dubious conclusions (vide 1 to 3, and A-B). In a footnote Weinstein states that his
SMITHIES F. THE GLYCYLTRYPTOPHAN (PEPTID) SPLITTING AGENT IN HUMAN SALIVA. Arch Intern Med (Chic). 1912;X(6):521-533. doi:10.1001/archinte.1912.00060240003001