Abstract
1. The prolongation of the shortest stain-time for the peroxidase reaction of blood leucocytes was very frequently found among mothers secreting milk negative to Arakawa's reaction and among infants nursed with the same, while it was not found among mothers secreting milk strongly positive to the Arakawa reaction.
2. The administration of vitamin B was able very soon to restore the prolongation in question to normal.
3. The prolongation in question was not found in those cases that had been taking vitamin B for some time already, whatever the diseases might have been.
4. The prolongation in question was mostly associated with the diseases or conditions which had something to do with avitaminosis B.
5. The prolongation in question was not a sign of agonal condition or of a severe moribund state.
