352 OCCURRENCE OF IODINE IN THE 



Baumann,* in which the thyroids of a small dog ingesting 26 

 pounds of thymus in sixteen days were found to contain 1.4 

 mgr. of iodine, loses the significance attributed to it, in view 

 of the later experiments of Roos.f The latter investigator 

 found that dogs frequently retain a considerable store of 

 iodine in their thyroids even after six weeks' feeding with 

 meat, a diet free from iodine. The results of a single brief 

 feeding experiment with thymus can therefore no longer be 

 regarded as a confirmation of the existence of iodine in the 

 gland fed. 



The favorable results which have been reported for the 

 thymus method of treatment in both true and exophthalmic 

 goitre have been confirmed more recently through the further 

 observations by Reinbach J in Mikulicz's clinic. The success 

 of thymus therapy indicates, as Reinbach points out, that the 

 peculiar action of thyroid preparations in reducing goitre is 

 nothing specific for the thyroid. Furthermore Cunningham 

 has demonstrated that thymus tissue yields substances equally 

 as capable as thyroid extractives of palliating the acute 

 cachexia in thyroidectomized dogs. That these substances do 

 not contain iodine is pointed out by Cunningham and is par- 

 ticularly emphasized by my own experiments. 



What light do these experiments throw upon the signi- 

 ficance of the iodine content of the thyroid ? It seems to the 

 writer that a variety of evidence leads to the conclusion early 

 announced by Hutchison, || that the physiological activity of 

 thyroid preparations is due to substances associated with the 

 iodine, rather than to that element itself. This, at least, 

 applies to the ordinary action of thyroid feeding in goitre. 

 Two reasons for this conclusion may briefly be stated. First, 

 the thymus, which shows marked similarity to the thyroid in 



* Baumann, Zeitschrift fur physiol. Cheinie, 1896, xxii, pp. 14-16. 



t Roos, Zeitschrift fur physiol. Chemie, 1899, xxviii, pp. 43-44. 



$ Reinbach, Abstract in Centralblatt fur die medicinischen Wissenschaf ten, 

 1899, p. 276. 



Cunningham, Journal of Experimental Medicine, 1898, iii, p. 225. 



|| Hutchison, Journal of Physiology, 1896, xx, p. 494 ; cf . also Reinbach, 

 loc. cit. 



