The change of femur bone marrow picture was examined after the lumbal sympathectomy of rabbits and dogs, and the results obtained were as follows: 1) No changes by macroscopic finding. 2) No changes of nucreated cell count. 3) Relatively increasing of erythroblasts, and decreasing of pseudoeosinphils (rabbits) or neutrophils (dogs), but those mitosis count both increased. 4) Erythroblasts, pseudoeosinophils (rabbits) and neutrophils (dogs) all indicated marrowright-shift, in other words, the promotion of the maturity. 5) Staff and lobed pseudoeosinophils (rabbits) or neutrophils (dogs) indicated decrease, in other words, the promotion of cell outswim or cell outflow. The above concludes that the intercreption of sympathic nerves of rabbits and dogs promotes mainly medullary cell outflow and maturiy.