After the removal of various centers of the motor cortex in dogs, investigations were made; i.e. The problem of exchange or migration of the motor centers proved by electric stimulation, the function of compensation, implicated arrangement of the nerve cells of the different centers and the compensation between both hemisphere. 1) In the remaining motor cortex a phenomenon of exchange of the motor centers was observed. The migration of the area for the hind limb (H.A.) into the area for the fore limb (F.A.) in case of the removal of H.A. and the mixed area (M.A), was more frequently observed than that of F.A. into H.A. in case of the removal of F.A and M.A. But no migration was observed when all of these F.A., M.A. and H.A. were unilaterally or bilaterally removed. 2) Recovery from paralysis of the fore limb in case of removal of F.A. and M.A. came later than that of the hind limb in case of removal of H.A. and M.A. And in case of the removal of all of these F.A., M.A. and H.A. the recovery of the hind limb came a little earlier than that of the fore limb. 3) When F.A. and M.A. were removed, a slight paralysis of the hind limb was mostly observed in addition to the paralysis of the fore limb. When the H.A. and M.A. were removed, however, the paralysis of the fore limb could hardly observed. This fact was also observed in cases of bilateral removal. 4) After unilateral removal of the motor cortex, when the paralysis of the according limbs had recovered, and then the motor cortex of the contralateral side was removed, there was seen paralysis of the according limbs as well as a slight paresis in the other side. 5) From the facts as above-stated, the implicated arrangement of the nerve cells in F.A. and H.A. could not be considered to be equal and the cells for the hind limb extended more frequently into F.A. than those for the fore limb into H.A.