Morphologic variations of the erythrocyte include, among others, modifications in cell size, shape, staining characteristics, nuclear morphology and the occurrence of cellular inclusions. These modifications are typically recognized in D. L. Romanowsky type dye-stained dry film smears of blood obtained from birds sustaining diverse physiologic and pathologic conditions. A dietary deficiency of folic acid in chickens results in an anemia that is morphologically characterized by the development of erythroblasts with a specific, well recognized maldevelopment. These erythroblasts are termed megaloblasts. The effects of ingested dimethyl disulphide on the hematologic profile of adult domestic fowl have been investigated by D. S. Maxwell. Of the twenty-seven-weeks-old female, laying, white leghorn Forsgate chickens that were placed on diets containing either one or two parts per million of aflatoxin for a period of 42 days, those that were maintained on the 2 ppm aflatoxin diet developed a significant drop in the hematocrit.