490 CHEMICAL PATHOLOGY OF THE DUCTLESS GLANDS 



Oswald obtained different results through analyses of the 

 colloid of colloid goiters, finding that colloid goiters contain a 

 thyreoglobulin that is relatively very poor in iodin ; in goitrous 

 calves the thyreoglobulin contained no iodin ; in human goiters 

 it contained but 0.07 to 0.19 per cent, of iodin, as against a 

 normal proportion of 0.34 per cent. Administration of iodides 

 to a goitrous patient caused a rise in the proportion of iodin in 

 the colloid to 0.51 per cent., showing that in colloid goiters in 

 goitrous districts the thyreoglobulin is probably poor in iodin 

 because of a lack of iodin for it to unite with, and not because 

 it is of an abnormal nature that prevents its chemical combina- 

 tion with iodin. 1 Possibly this explains the greater iodin con- 

 tent observed in colloid goiters in the United States as compared 

 with colloid goiters observed in goitrous districts. In general, 

 Oswald 2 found the amount of iodin to vary with the amount 

 of colloid in the goiters, although occasionally goiters with 

 exceptionally large amounts of iodin were found, and the pro- 

 portion of iodin is not usually so great when the amount of 

 colloid is very large. Simple hyperplastic goiters he found 

 poor in iodin, or free from it if they contained no colloid ; 

 however, they were found to contain a thyreoglobulin typical 

 in all respects except an absence of iodin. Presumably in such 

 goiters the little thyroiodin present is contained in the paren- 

 chymatous cells. The physiological activity of thyreoglobulin 

 obtained from goiters was found to be the same as that from 

 normal glands, except that it was weaker in direct proportion 

 to the amount of iodin it contained, and, therefore, when iodin- 

 free it was without effect. In colloid goiters the greater part 

 of the weight of the gland, three-fourths or more, is made up 

 of this colloid-poor thyreoglobulin. The fluid contents of 

 cystic goiters may be free from iodin, but if they contain much 

 colloid, iodin will be found, and Rositzky 3 found 193 mg. of 

 iodin in 20 c.c. of the jelly-like contents of a thyroid cyst. 



It has been frequently suggested that the cause of endemic 

 goiter is a deficiency in the iodin in the food, or in the drink- 

 ing-water, or in the air of the goitrous district. This is sup- 

 ported by the relative infrequency of endemic goiter in districts 

 on the sea-coasts, where the iodin-containing sea-water is sprayed 

 through the air, and where the inhabitants eat largely of sea- 

 foods. However, there are many exceptions, and it cannot be 

 said that this hypothesis of the etiology of goiter rests on 



1 See Kocher, Mitt. a. d. Grenzgeb. Med. u. Chir., 1905, vol. 14. 

 'VirchoVs Arch., 1902 (169), 444. 

 8 Wien. klin. Woch., 1897 (10), 823. 



