dilute sulphuric acid. The final filtrate is free from iodiue. Thyrojodin is then present in the thyroid glaud in small amounts in a free state; by far the larger part is united to an albumin (" tbyrojodalbu-min") and a smaller part is joined to a globulin (" thyrojodglobulin"). The existence of these com-pounds presumably explains the variable quality of the aqueous aud glycerine extracts. The thyrojodin seems to be active as a substance and not merely by virtue of its content of iodine. Given three or four times in doses of 0.001 gm. it has a positive aud distinct action on goitrous thyroids—an effect which the actual amount of iodine (that is, 0.0001 gm.!) is not known to produce. The action of thyrojodin is apparently even more rapid than that of the fresh gland. This is explicable if we suppose the thyrojodin to be set free but slowly by the diges-tive processes and that putrefactive processes in the intestines (resembling the action of sodium amalgam) may render some of the thyrojodin inert. If thyrojodin itself be given we may suppose the absorption to be more rapid and that putrefactive changes will be avoided.