Fred C. Koch 



109 



Table II gives a summary of the results above. The relative 

 physiological activity is expressed (on the basis of feeding the same 

 amount of iodine in each case) as follows : representing in each case, 

 by 100, the largest dose of acetonitrile from which the thyroid- 

 tissue fed mice recovered, then the other figures represent the 

 proportions the limiting doses of the otherwise fed mice bear thereto. 



TABLE II. 



These results show that both the thyroid activity and iodine 

 may be concentrated from thyroid tissue in the thyreoglobulin 

 as well as in the metaprotein and iodothyrin from the latter. Per 

 unit of iodine, however, we have full activity retained in the thyreo- 

 globulin and metaprotein only. In the primary albumose frac- 

 tion we have a lowering in the percentage concentration of iodine 

 and also a slight lowering in the physiological activity per unit 

 of iodine. In the secondary albumose this is still more marked. 

 In the amino-acid fractions the activity is extremely low if present. 

 In view of the researches of Hunt and Seidell with various iodine 

 compounds and in view of the results obtained here, we cannot 

 attribute the protective action in any of these cases to iodine itself, 

 but to a specific iodine-containing complex in the thyreoglobulin. 

 It is significant to note that the highest physiological activity per 

 unit of iodine is found in the original protein and in the more com- 

 plex products of hydrolysis. Since the lowest products of hydroly- 

 sis are still less active per unit of iodine than the secondary albu- 



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