Abstract
Young rats placed on a milk diet (12% solution of Klim in distilled water) at about 21 days of age, grow about as well as rats do on the stock, Sherman B, diet and exhibit no evidences of avitaminosis. In 3 to 6 weeks the Hb falls to 4 or 5 gm. per cent, and the red cells to 4 or 5 million in contrast to the usual values at this age of 13 gm. per cent and 8 million. Control experiments indicate that a more severe anemia can be produced by fresh dairy milk. These anemic rats will not breed. Litters have been procured by transferring females to the stock diet and mating them with males that have always been on this diet. When the young are about 21 days old they are similarly put on the milk diet. The Hb per cent and the number of red cells decrease more rapidly than they did in the first generation. When the low levels are reached some of the animals die, but the majority show a tendency to a slow spontaneous recovery. Hb values of less than 4 gm. per cent are fatal in the majority of cases.
The red cells in this type of anemia vary considerably in size and shape and many of them show polychromatophilia. The average corpuscular volume is 35 cu. microns as compared with 51 cu. microns for the normal red cell, and the saturation is low, 30% as compared to 40% in the normal cell. During the spontaneous recovery the stroma increases more rapidly than the Hb so that in the later stages the saturation is further diminished. An increased resistance of the red cells to hypotonic solutions is a striking and constant feature of this anemia.
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