Three mechanisms may be concerned in the production of anemia: (1) hemorrhage, (2) diminished production of blood or impaired delivery of erythrocytes from the hematopoietic tissue into the circulation and (3) destruction of blood. One might add hydremia, as, judged by the ordinary methods of clinical investigation, it would appear to be anemia.
In order to decide which of the aforementioned factors is active in the production of the common forms of secondary anemia, we attempted to determine whether in those conditions there is an abnormality in the formation or destruction of red blood cells. In this investigation we relied on the fact that the reticulated cell count furnishes the most accurate index of bone-marrow function available, and that the icteric index is a simple and reliable measure of breakdown of hemoglobin, except in patients with hepatic lesions or obstructed biliary passages.
Much work has been done recently both with