604 IODINE AND THE THYROID. Ill 



inorganic iodine? It would seem that if iodine is merely an activator 

 of the thyroxin of the thyroid gland, then every cell in the organism 

 elaborates thyroxin or else a thyroidless tadpole could not meta- 

 morphose under the stimulus of inorganic iodine. , A view that appeals 

 to the writer is to assume that iodine when taken into the body acts 

 upon all the cells of the organism by stimulating intracellular oxida- 

 tions in each cell and tissue. It is unnecessary to assume that 

 iodine is used per se for any purpose, and from this viewpoint there 

 is nothing against the idea that iodine acts as an organic catalyst.^" 



It has been shown that patients with complete atrophy of the thy- 

 roid have basal metabolic rates 40 per cent below normal. The 

 question arises as to what maintains energy output from 100 per cent 

 below normal, which would mean death, up to 40 per cent below nor- 

 mal, the point to which basal metabolism sinks in the absence of 

 the thyroid. Kendall attempts an answer to this question which he 

 himself raises, by assuming that there are other chemical substances 

 in the body possessing the same grouping that occurs in his thyroxin. 

 Such substances according to Kendall are amino-acids and proteins, 

 creatine and creatinine. A more probable assumption, in the light 

 of the iodine experiment on thyroidless tadpoles, is that the basal 

 metabolism of patients suffering from athyreosis is prevented from 

 sinking below 40 per cent by the iodine which is taken into the body 

 in their food and drink, and which is absorbed and used by the cells 

 and tissues of the organism without the necessity of its undergoing 

 transformation in the thyroid gland tissue. This is exactly what 

 occurs when iodine is fed thyroidless tadpoles. Moreover, the 

 basal metaboHsm of thyroidless frog larvae is low. Apparently, 

 what keeps it sufficiently high for the continuance of the life proc- 

 esses is the minute quantities of iodine taken into the body in the 

 food and water. 



However iodine may act physiologically, the writer feels certain of 

 his ground in asserting that bromine cannot be substituted for it. 



1° The writer suggested in a recent paper^ that the thyroid gland probably did 

 not elaborate an internal secretion. This meant that the gland did no more 

 than the other cells and tissues of the organism could do, if they were given 

 the appropriate conditions. Certainly the evidence obtained from the meta- 

 morphosis of thyroidless tadpoles under the stiaiulus of iodine feeding strongly 

 indicates this. 



