With transparent specimens (Spalteholz's method) injected with dyes and tissue sections, the author studied the developmental course of medullary vessels in tne scapula of 60 human embryos for the periods covering the first embryonal stage to the terminal stage, and obtained the following results. 1) The primary bone marrow in scapula starts its formation in the latter part of the third embryonal month (twelfth gravid week) with the primary medullary primordium which penetrates into three sites in the neck of scapula. 2) Nutrition arteries and veins (A. and V. nutricia) start to develop along with the enlargement of the primary medullary spaces and are distributed beginning at the neck of scapula radially and extensively, and veins, with no distinction of trunk and capillary, possess the vascular diameter far larger than that of arteries, presenting a picture of intra-tissue spaces. 3) By the fouth embryonal month, enchondral ossification starts, and along with the progress of bone formation the central part of scapula is almost completely occupied by bony substance. In the latter part of the fourth embryonal month, the blood vessel system is divided into two parts having the base of spina scapulae as the center, at the same time auxiliary nutrition vessels begin to penetrate into spongy substance of residual Margo vertebralis, thus offering an aid to the blood circulation. 4) No marked changes with the progress of gravid month can be observed in the mode of distribution of medullary vessels later than the fifth embryonal month. The nutrition artery enters into scapula from the base of spina scapulae and divides itself into two branches. One of the branches runs along the lower edge of the base of spinsa capulae towards Margo vertebralis while the other descends along Margo axillaris and on its way anastomoses with nutrition arteries coming from one or two other nutrition canals, and finally sends out minute capillaries, elongating extensively cross-wise along Margo vertebralis; and these capillaries surround the central part of bony substance. Now the trunk and peripheral vessels can be distinguished in nutrition veins. 5) The minimum of two, the maximum of ten and usually 4-6 of nutrition canals have been recognized, and a slight tendency of an increase in number of these canals is observable along with the progress of growth. The largest and most commonly found nutrition canal is located at the base of spina scapulae. and when other canals do exist, they are generally located at a fixed location. 6) In the beginning of the fourth embryonal month, cartilaginous canals appear near the root of coracoidal process in the cartilarginous part of Fossa articularis, and assuming a peculiar mode of development, many of these canals are seen penetrating into the vicinity of the cartilaginous part of Fossa articularis and into the coracoidal process; and in the seventh embryonal month one of these canals is communicated with the medullary vessel of Fossa articularis.