H. B. van Dyke 13 



quantitative determinations of iodine were made by the method 

 of Kendall (6). 



From the data of Table I it can be seen that large amounts of 

 iodine as KI were taken up by hyperplastic thyroid glands despite 

 big variations in the dose of KI (50 to 150 mg.) and duration of time 

 between injection and removal of gland (90 seconds to 22 hours 

 and 25 minutes). The cooling of the blocks of thyroid tissue dur- 

 ing the process of cutting had little effect. Either little of the 

 injected iodine was held by the cells, or it diffused rapidly from the 

 cells in the process of cutting; for the iodine content of the cells 

 and hence the ratio of the precentage of iodine in cells to the per- 

 centage of iodine in whole gland is considerably less than that 

 found in resting glands. The average ratio value of 0.15 for the 

 dog (4) was approached only in Experiment 11 in which nearly 

 24 hours elapsed between the injection of KI and the removal of 

 the experimental lobe. In this last case there are alternative 

 means of explanation: more iodine may have been bound by the 

 cells by removal from the thyroid's intercellular spaces, or the iodine 

 in the cells was in a less diffusible form than in the other experi- 

 ments of the series. These changes in the distribution of iodine 

 after about 24 hours can be definitely correlated with Marine and 

 Rogoffs (3) discovery that 20 hours after the injection of iodine as 

 KI, markedly hyperplastic glands exhibit more stainable colloid 

 with some increase in the size of the follicular spaces and shrinkage 

 in the height of the columnar epithelium. 



In the experiments the data of which are given in Table II, 

 solutions of colloid iodine from normal dog thyroid glands were 

 injected intravenously to determine to what extent iodine in 

 organic combination is bound by hyperplastic thyroid glands. 



The iodine of thyroid colloid of normal animals is practically 

 not at all taken up by hyperplastic glands after 42 to 86 minutes. 

 A comparable amount of iodine in the form of KI is rapidly 

 taken up. 



Blum and Griitzner (7) found some hours after the injection 

 into the circulatory system of fluid pressed from thyroid glands 

 that the iodine-containing thyroid protein is split largely by 

 hepatic action into simpler products with the formation even 

 of iodides. In Experiments 12 and 13 (42 and 86 minutes after 

 intravenous injection) there is little evidence that much iodide- 



