1. Periosteal bone is supplied by periosteal vessels and endochondral bone by the nutrient artery.

2. In the earliest stages of development the metaphysis is supplied by vessels derived only from the nutrient artery. Later, metaphysial arteries derived from the periosteum take over the supply of its peripheral part, the extent of their area of supply progressively increasing.

3. In injected specimens the blood vessels approaching the epiphysial cartilaginous plate end in saccular dilations. Histological sections show these dilations to be blood-filled cartilage lacunae, with no endothelial lining and into which open the blood vessels approaching the epiphysial plate.