Experimental evidence and clinical experience have fully established the calorifacient action of thyroid substance in thyroidectomized animals and in man with hypothyroidism. Published studies of normal animals1 and of men and women without hypothyroidism2 are not as conclusive, but in general they tend to show that the drug induces a similar but less constant response in these subjects. To our knowledge, the literature contains few references to similar metabolic studies in infants and children without hypothyroidism.3 Such investigations should be of physiologic interest and of clinical assistance in appraising the rôle of thyroid therapy in these subjects in other than hypothyroid states.
Another phase of the thyroid problem that merits further study relates to the relative potency of the different commercial preparations in common use. At the present time, the drug is officially standardized according to its iodine content. This method of standardization was adopted chiefly as