16 
to that of thyroid.® Since most writers have found either no iodine 
in the thymus or only traces (in which case it was usually attributed 
to admixture with thyroid b ) the conclusion has been drawn that 
thymus free of iodine has a physiological effect similar to that of 
thyroid. In reply to this it may be stated that later writers seem 
to be agreed that thymus has very little activity in goiter. Even 
granting that thymus does possess a certain degree of activity of a 
character similar to that of the thyroid, this would not prove that 
iodine is not a very inqmrtant constituent of the thyroid. One of 
the present writers 0 recently showed that there is present in several 
organs of the body a substance or substances having a physiological 
action similar, at least in some respects, to that of thyroid, but that 
the latter, apparently on account of its iodine content, is far more 
active. 
d. Inefficiency of iodothyrine in tetany. — Another argument against 
the view that the iodine-containing substance (iodothyrine) obtained 
from the thyroid by Baumann is the active constituent of the thyroid 
was that it did not prevent tetany in thyroidectomized animals .' d 
These experiments were performed before the importance of the 
parathyroids was 'recognized and the investigators were endeavoring 
to control symptoms with which the thyroid had little or nothing 
to do. 
e. Efficiency of iodine compounds other than iodothyrine in goiter . — 
Baumann argued that iodothyrine was the active principle of the 
thyroid from the fact that its administration produced the same 
effects upon certain forms of goiter as did that of the thyroid itself. 
But attention was called to the fact * * * 6 that a great variety of iodine 
compounds, both inorganic and organic, had a similar effect in these ! 
conditions. Evidently, however, such arguments do not bear directly 
upon the question whether the iodine is of importance to the thyroid. 
Recent work indicates that these different forms of iodine are effi- 
cient simply because the iodine has a special affinity for the thyroid. 
The effect of iodine in the treatment of goiter is in reality an argu- 
ment in favor of the view of the importance of iodine in the thyroid. 
A very little consideration suffices to show that none of the above 
arguments have any very direct bearing upon the problem with which 
a J. Mikulicz, Berl. klin. Wchnschr., 1895, 32, p. 342; G. Reinbach, Mitt. a. d. 
Grenzgeb. d. Med. u. Chir., 1898, 3, p. 309; R. H. Cunningham, J. Exper. Med., N. 
Y., 1896, 3, p. 227. 
& E. Baumann, Miinchen. med. Wchnschr., 1896, 43, p. 311; R. H. Cunningham, 
1. c.; H. G. Wells, J. Am. M. Ass., Chicago, 1897, 29, p. 1009; L. B. Mendel, Am. J. 
Physiol., Boston, 1900, 3, p. 285. 
c R. Hunt, J. Am. M. Ass., Chicago, 1907, 49, p. 1325. 
d cf. G. von Bunge, Lehrbuch der Physiologie des Menschen, 2 ed., 1905, 2, p. 632; 
E. Roos, Ztschr. f. physiol. Chem., Strassb., 1899, 28, p. 41; 1899, 27, p. 37. 
e cf. Yon Bunge, 1. c. " I 
