The researches have had in view the anatomical localization of the anti-anæmic factor (Castle's “intrinsic factor”) in the stomach.As the pig's stomach is peculiarly constructed, having a so-called cardiac-gland region, a fundus-gland region and a pyloric gland region continued in the glands of Brunner in the duodenum, preparations have been made from each of these regions, and tests of the effectiveness of each of these separate portions have been made in cases of pernicious anæmia. It has previously been pointed out (Meulengracht and Schiødt) that the production of hydrochloric acid, pepsin and rennin was confined to the glands of the fundus region (peptic glands) with their oxyntic cells and chief cells.The experiments showed that the extract of the fundus-gland portion was inactive in cases of pernicious anæmia, that of the so-called cardiac-gland portion was mildly active, that of the pyloric-gland portion was strongly active, and that of the duodenal portion was also strongly active. The feebler activity of the cardiac portion might be shown to be a result of the smaller number of glands to the unit area in that region.The conclusion drawn from the experiments is that the so-called cardiac glands, the pyloric glands and the Brunner glands in the duodenum, which anatomically may be said to be very nearly identical, may also be taken to be functionally identical, at any rate with regard to the production of the anti-anæmic factor.This collective gland region, which it is proposed to call the pyloric-gland region, is the site of the production of the anti-anæmic factor. There is thus attributed to these glands a definite, well-defined and vitally important function.It is further concluded from the experiments that pernicious anæmia in human beings is due to atrophy and inactivity of that part of the stomach which comprises the pyloric-gland region. The experiments may thus be said to have anatomically localized pernicious anæmia in human beings.Experimental pernicious anæmia will presumably be producible by the deliberate removal of the pyloric-gland region.Stomach preparations for the treatment of pernicious anæmia will with advantage be producible from the pyloric-gland region alone.