Investigating the bone-marrow pictures and the O(2)-consumption as well as the glycolysis in the bone marrow both of the hook-worm anemics and of the hook-worm dogs, the author, in comparison with those of the bleeding anemia reported in Part II, arrived at the following conclusions: 1. On puncturing the sternum of hook-worm anemics, a picture of maturity arrest was revealed in their bone-marrow picture. On the other hand, in the bone marrow of hook-worm dogs (oral infection with 500 larvae), a bleeding-anemia picture had been revealed at the early stage of anemia, but along with the aggravation of the disease, a picture of maturity arrest was recognized. 2. The slight increase of the O(2)-consumption and an increase of the anaerobic glycolysis were observed in the punctuate of the hook-worm anemics. 3. In the bone marrow of dogs orally infected with 1, 000 larvae, the rate of the O(2)-consumption had increased at the early stage while it decreased along with the aggravation of anemia. 4. In the bone marrow of the dogs receiving 500 oral larvae, the rate of the O(2)-consumption also increases at the early stage, and though lowering gradually along with the aggravation of the disease, it never goes below the normal rate. Whereas the rate of anaerobic glycolysis has been seen to rise by degrees in proportion to the degree of anemia. 5. On comparative observations, the effects on the O(2)-consumption of the normal-rabbit bone marrow injected with the serum of the hook-worm anemics differ not in any great extent from those of the normal-rabbit bone marrow injected with the serum of normal person. 6. The oxygen consumption and glycolysis of the bone marrow of the hook-worm anemia differ from those of the hemorrhagic anemia; and of the causative factors of this disease, not only the hemorrhagic factor but also the toxic factor seem to play very important roles.