The gross blood supply of the thyroid gland is a matter of common knowledge, but the finer details of the circulation are not well described. There are certain facts about the vascularity of this organ that make for difficulty in demonstration and description. The thyroid is said to have the richest blood supply of any organ in the human body. This high degree of vascularity is well illustrated in the figures given by Burton-Opitz.1 In his chart for the volume of blood per minute per hundred grams of organ, the thyroid heads the list. It receives 560 cc. of blood per minute per hundred grams. This is from two to ten times the quantity given for other organs. Such a great volume per minute can be possible only in the presence of a rich capillary bed. This highly vascular character provides such a complex network of vessels as seen