13 
found no iodine in the thyroids of cattle.® Roos 6 found no iodine 
in the thyroids of three foxes; none in that of a polecat; none in that 
of a wild cat; he found it in but two of six martens; it was absent 
from the thyroids of four domestic cats and present in but traces, 
or in very small amounts, in those of five others; it was absent in 
four of eleven dogs, in two of four horses, and three of seven hogs. 
In many cases the presence or absence of iodine is dependent upon 
the character of the food which the animal has received. 
The thyroids of herbivorous animals, whose food usually contains 
small amounts of iodine, are almost always richer in this element 
than are those of carnivorous animals, whose food is usually poor in 
iodine. c Sheep pastured near the sea may have double the amount 
of iodine in their thyroid as those pastured in inland regions . 1 d The 
amount of iodine in the thyroid of omnivorous animals (hog, dog, 
man) is especially variable. Nagel and Roos e found the percentage 
in the dried glands of hogs to vary from 0 to 0.075, although the 
glands were obtained from the same slaughterhouse/ Baumann 
found the percentage of iodine in the thyroid of horses to vary from 
0.06 to 0.17/ 
As a rule it is not possible to detect any difference between the 
animals which have a large percentage of iodine in their thyroids 
and those which contain none or only traces; removal of the gland 
is fohowed by as severe symptoms in the latter as in the former. 
Thyroid free of iodine seems to meet the needs of the body as well as 
the thyroid that contains iodine/ 
Human thyroids also contain quite variable amounts of iodine, 
as was first pointed out by Baumann. 1 ’ Join/ has recently summar- 
ized the entire literature on the occurrence of iodine in the thyroid 
of man and has reported a very large number of analyses of such 
thyroids obtained in Sweden; he found great variations in the per- 
centage of iodine and was unable to discover any constant relation 
between its presence or amount and conditions of health or disease. 
He asks, “Can not the great variations in the iodine content of not 
only pathologically altered thyroids but also of normal glands, and 
especially the fact that thyroids may be found in adults as well as 
in children which contain no iodine or scarcely traces of it, simply 
depend upon the fact that the iodine is an accidental constituent 
a Topfer, Wien. kiln. Wchnschr., 1896, 9, p. 141. 
fi E. Roos, Ztschr. f. physiol. Chem., Strassb., 1899, 28, p. 55. 
C E. Roos, 1. c. 
d Th. Suiffet, J. de pharm. et chim., Par., 1900, [6] 12, p. 50. 
e W. G. Nagel and E. Roos, Arch. f. (Anat. und) Physiol., Suppl.-Bd., 1902, p. 267. 
/ A specimen of hog thyroid examined by us contained 0.33 per cent iodine. 
0 Baumann, Ztschr. f. physiol. Chemie, Strassb., 1896, 22, p. 17. 
Exceptions to this will be referred to later. 
*'E. Baumann, Ztschr. f. physiol. Chem., Strassb., 1896, 22, p. 1. 
3 S. Jolin, Festschrift, O. Hammarsten, Upsala, 1906. 
