DISTRIBUTION OF BLOOD GROUP PROPERTIES AND BLOOD GROUP PROPERTY DESTROYING FACTORS IN THE INTESTINAL TRACT OF MAN.

1. The blood group specific substance A is present in the contents of the jejunum and upper ileum of persons belonging to Group A. 2. A marked decrease in the amount of A substance occurs in the lower ileum and cecum, while colon and rectum contents of adults are more or less free of group substance A. 3. The blood group destroying agent first appears in the lower ileum or cecum and its effectiveness increases in the lower parts of the large intestine. 4. In two cases with intestinal obstruction the blood group destroying agent could be demonstrated in the contents of the jejunum and ileum.