In 1937 Haden and Evans1 described red blood corpuscles shaped in the form of a "Mexican hat" or a "sugar loaf." They claimed that these cells occur only in sickle cell anemia. A year later Barrett,2 in an extensive study, showed the presence of these bodies (which he named "target corpuscles") in such varied conditions as obstructive jaundice, a "hypochromic" group of anemias in which the color index was not more than 0.8, steatorrhea, and following splenectomy. An interesting case of erythroblastic anemia in a young adult with target cells was described by Dameshek.3 In a more recent paper Singer, Miller and Dameshek4 discussed hematologic changes following splenectomy in man with particular reference to target cells and their physicochemical behavior.
THE TARGET CELL
In Wright's stained preparations, these red cells may vary from 7 to 10 microns in diameter. A small central mass of hemoglobin surrounded