606 CHEMICAL PATHOLOGY OF THE DUCTLESS GLANDS 



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 combination 

 with iodin.*'" Possibly this explains the greater iodin content observed 

 in colloid goiters in the United States as compared with colloid goiters 

 observed in goitrous districts. In general, Oswald" 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 proportion 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 parenchymatous 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 thyreoglobuKn. The fluid contents of 

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

 iodin will be found, and Rositzky*''^ found 0.193 mg. of iodin in 20 c.c. 

 of the jelly-hke 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 drinking-water, or in 

 the air of the goitrous district. This is supported by the relative in- 

 frequency 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. Also administration of minute 

 amounts of iodin, even in the air, seems to reduce existing goiter and to 

 prevent its occurrence in inhabitants of goitrous districts.''"' However, 

 there are many exceptions, and it cannot be said that this hypothesis 

 of the etiology of all goiter rests on satisfactory evidence, particularly 

 in view of the abundant iodin content of colloid goiters. Epidemics 

 of goiter presumably are the results of an infection with some unknown 

 organism, and possibly the endemic form has a similar cause. "^ - There 

 is much evidence, in any event, that whatever the cause of goiter may 

 be, it often is related to the drinking water,"" but numerous well-con- 

 trolled experiments fail to support this hypothesis."" Verj^ probably 



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



" Virchow's Arch., 1902 (169), 444. 



" See Oswald, Arch. ges. Physiol., 1916 (164), 506. 



" Wein. klin. Woch., 1897 (10), 823. 



«•• See Hunzikcr, Corr. Bl. Schw. Aerzte, 1918 (48), 220. 



" See McCarrison, "The Thyroid Gland," New York, 1917. 



"8 See de (^uervain, Mitt. a. d" Grenzgeb. Med. u. Chir., 1905 (15), 297; Birchcr, 

 Zeit. exp. Path. u. Ther., 1911 (9), 1. 



" See Munch, med. Woch., 1913 (60), 393 and 1813; Sitzber. Wien. Akad., 1914 

 (123), 35. 



