18 
was produced by the administration of the thyroid containing the 
larger percentage of iodine. In the third experiment, in which the 
dried thyroids of dogs were administered, 5 grams of a preparation 
containing no iodine had no effect, whereas 5 grams of a preparation 
which contained 0.35 per cent iodine was followed by a distinct in- 
crease in the nitrogen excretion and a slight loss of weight. 
Roos’s experiments were very few in number and the results not 
very striking, and perhaps do not justify the very positive conclusions 
he drew from them.® Still they point very distinctly to the conclu- 
sion that thyroid rich in iodine has a more marked effect upon 
nitrogen metabolism than does thyroid poor in, or free of, iodine. 
Roos also describes the effects of desiccated hog thyroids contain- 
ing different percentages of iodine upon four cases of parenchymatous 
goiter. In all cases thyroid free of iodine had a very slight or doubt- 
ful effect, whereas thyroid containing iodine had a marked action in 
reducing the size of the goiter. In one case the use of doses of 0.5 
gram thyroid containing 0.008 per cent iodine had a distinct effect, 
but the effect of the administration of equal doses of a thyroid con- 
taining 0.08 per cent iodine was more marked. 
Roos himself recognized that only an approximate estimation of the 
quantitative effects of thyroid was possible either in metabolism ex- 
periments or in the treatment of goiter. He also pointed out the 
difficulties of drawing any conclusions from observations upon thy- 
roid-ectomized animals, and stated that he deemed it useless to try 
this method. 
Oswald tested the activity of thyreoglobulin containing little iodine 
upon metabolism, and von Cyon investigated its effects upon the irri- 
tability of the vagi . * 6 In the two experiments upon metabolism 
reported by Oswald the thyreoglobulin poor in iodine produced no 
effect in one case and very slight, if any, in the other ; thyreoglobulin 
rich in iodine produced a marked increase in the nitrogen excretion. 
Von Cyon reported that thyreoglobulin obtained from colloid goiters 
and which contained 0.19 per cent iodine had a distinct effect upon 
the irritability of the vagi, but that this was less than that produced 
by normal thyroid with a higher percentage of iodine. Von Cyon 
and Oswald 0 had already found thyreoglobulin free of iodine ob- 
tained from goitrous calves to be without any effect upon the circula- 
tion. Oswald further states that thyreoglobulin from hog thyroid con- 
taining 0.5 per cent iodine seemed more active than that of the human 
thyroid with 0.3 per cent iodine.^ 
® cf. F. Blum, Verhandl. d. Kong. f. inn. Med., 1906, 23, p. 196. 
& A. Oswald, Arch. f. path. Anat. [etc.], Berl., 1902, 169 , p. 461; Beitr. z. chem. 
Physiol, u. Path., Brnschwg., 1902, 2, p. 555. 
c E. von Cyon and A. Oswald, Archiv. f. d. ges. Physiol., Bonn, 1901, 83, p. 202. 
^A. Oswald, Beitr. z. chem. Physiol, nr. Path., Brnschwg., 1902, 2, p. 556 (footnote). 
