Section IV., 1914. |7] Trans. R.S.C. 



The Distribution of Iodine in Plant and Animal Tissues. 



By A. T. Cameron. 



From the Department of Physiology and Physiological Chemistry, 

 University of Manitoba, Winnipeg. 



(Presented by Professor Swale Vincent, F.R.S.C.) 

 (Read May 26, 1914.) 



From a biological standpoint the two facts of paramount impor- 

 tance in the history of iodine are the discovery of the element itself 

 in sea-weed in 1811 by Courtois, and the discovery of its presence in 

 the thyroid gland by Baumann in 1885. Subsequent to this date 

 investigations have been directed chiefly with the aim of discovering 

 the function, if any, of iodine in the thyroid. A very large number of 

 papers have appeared, whose chief result seems to be to throw into 

 doubt all the earlier conclusions derived from the work of Baumann 

 and his followers (as for example that the iodine of the thyroid is 

 present organically combined in a relatively simple compound "iodo- 

 thyrin," to which is due the activity of the gland as a secretory organ), 

 without presenting a more defensible theory. 1 



Various conflicting statements have been put forward as to the 

 presence or absence of iodine in other mammalian tissues, especially 

 those of the glands of internal secretion. More definite data are 

 available for certain invertebrates. Thus the presence of iodine in 

 Sponges was discovered by Fyfe in 1819, and confirmed by numerous 

 investigators, 2 while Drechsel first pointed out its presence in corals. 3 

 Numerous investigations have shown that it is present in almost 

 all Sea-weeds. 



The fact that when a diet rich in iodine is administered to an 

 animal such as the dog, the iodine content of the thyroid is markedly 

 and rapidly increased, was pointed out by Baumann himself, 4 and 

 has been repeatedly confirmed. The known variations of iodine 



1 See in this connection, Swale Vincent "Internal Secretion and the Ductless 

 Glands," Arnold, London, 1912, p. 311, and Biedl, "Innere Sekretion" 2te Aufg., Bd. 

 1,S. 211. 



2 Cp. Harnach, Munch, med. Wochenschr., 43, 196. 



3 Z. Biol., 33, 85, 1896. 



4 Baumann and Goldmann, Munch, med. Wochenschr, 43, 1153, 1896. 



