Having performed various experiments about rabbits of experimental anemia, in order to clarify causes of anemia, by injection of anemia-producing substance, obtained results as follows: 1) As to spleen-extirpated rabbit, it has incurred anemia by injection of serum. 2) The same would take place in case of liver-disturbed rabbit, due to serum injection. 3) No anemia was observed with the same injection, when the reticuloendothelial system was blocked with Indian ink. 4) Injecting the serum at a, nutricia femoris, and investigating the blood picture at v, nutricia femoris discovered a marked decrease both in the number of erythrocytes as well as leucocytes 2 hours later. 5) The serum iron value has proved a rise at the maximum anemic stage, in the successive injection. 6) The myelogram of the rabbit in case of successive injection, indicated a picture of maturation-arrest. 7) By all these facts stated above, it might be said, as for the factor to renderrabbit anemic, blood cell-arrest within bone marrow could be considered on one side, while the disturbance in the parenchym of the bone marrow might be imagined on the other.