15 
albumin and nucleo- albumin prepared from the spleen to be inactive. 
Blum® had also found iodized albumin almost without effect upon 
metabolism. Hutchinson also increased artificially the percentage of 
iodine in colloid derived from the thyroid. Although such a product 
contained nearly ten times as much iodine as the original material, 
it had no greater physiological activity. Hutchinson drew the fol- 
lowing conclusions from these results: 
One would conclude from the whole evidence that the iodine in the thyroid gland, 
if it plays an essential part in the activity of the latter at all, does so simply in virtue 
of the special form of combination in which it is present. * 5 
Hutchinson had apparently concluded from earlier work that not 
much importance w T as to be attached to iodine as a factor in deter- 
mining the activity of the thyroid. Thus in 1896 he wrote as follows : c 
It must not * * * be supposed * * * that the iodine is necessarily the 
essential factor in the activity of the thyroid gland. One has only to realize the 
small proportion in which it is normally present — only a few milligrams in a whole 
gland — to be convinced of that. * * * Baumann has himself failed to find any 
iodine at all in the thyroid of some children. Yet I suppose such a gland is none 
the less active. 
Blum d and Boos 6 had also early pointed out that thyroid proteins 
or iodothyrine to wdiich iodine had been added in vitro w 7 * 9 ere physio- 
logically inactive or less active than the natural products containing 
much less iodine. Blum used this observation as an argument against 
the view that the iodine is a factor in the physiological activity (or 
11 toxicity,” as Blum denies that the thyroid produces an internal 
secretion) of the proteins of the thyroid; he applied this view also to 
the iodine wdiich has been taken up by the living gland, maintaining 
that the iodization in vivo is strictly analogous to that in vitro. Boos f 
endeavored to disprove Blum’s theory by feeding iodine to dogs until 
the iodine content of the thyroid had been considerably increased; 
he stated that such thyroids show r ed increased physiological activity. 
Blum^ points out that Boos’s figures are hardly conclusive in this 
respect. We have recently studied this phase of the subject, using 
new methods for determining the activity of the thyroid, and have 
completely confirmed Boos’s results. (See Part II of this bulletin.) 
c. The value of thymus in goiter. — Further arguments against the 
view- that the iodine is an important constituent of thyroid have been 
based upon the statements that thymus has. an effect in goiter similar 
® F. Blum, Munchen. med. Wchnschr., 1898, 45, p. 270. 
5 Similar views have been expressed by G. Reinbach, Mitt. a. d. Grenzgeb. d. 
Med. u. Chir., 1898, 3, p. 309, and L. B. Mendel, Am. J. Physiol., Bost., 1900, 3, p. 
290. 
c R. Hutchinson, J. Physiol., 1896, 20, p. 494. 
d F. Blum, Munchen. med. Wchnschr., 1898, 45, p. 335 . 
e E. Roos, Ztschr. f. physiol. Chem., Strassb., 1898, 25, p. 242. 
f E. Roos, Ztschr. f. physiol. Chem., Strassb., 1899, 28, p. 40. 
9 F. Blum, Yerhandl. des Kong. f. inn. Med., 1906, 23, p. 196. 
