1. Attention is directed to the diversity of opinion among investigators regarding the site and manner of hemoglobin formation in the body and its relation to bile pigment metabolism.
2. It is probable that in forming new hypotheses on this subject the earlier work of A. B. Macallum on the relation of chromatin to hemoglobin formation has not received sufficient consideration.
3. It has been shown by means of microchemical iron stains of the bone marrow cells, that the iron content of the hematoblast is increased during rapid hemoglobin production in simple anemia.
4. This fact is compatible with the work of Macallum who believed that hemoglobin is derived from the chromatin of the hematoblast. It does not support a theory that hemoglobin is formed as a part of a circulating pigment.
5. It is suggested that bilirubin is derived from the chromatin of body cells through the intermediary stages of the respiratory pigments, hemoglobin and cytochrome, from erythrocytes and other cells, respectively.