958 



THE INTERNAL SECRETIONS 



and certain types of rachitis fetalis from which it must, therefore, be differentiated. 

 This cUnical picture may be cleared up in the course of a month or two by the feeding 

 of thyroid substance or of an extract of thyroid. Growth begins again, the myxe- 

 dematous symptoms disappear more or less completely, and the infant brightens 

 up perceptibly from week to week. In our own country myxedematous cretinism 

 is rather rare, but there are several regions in which it is endemic; for example, 

 in Italy which reported 13,000 cases in 1883, and in Austria, Savoy, the Pyrenees, 

 the Himalayas and the Cordilleras. Since these districts are mountainous and 

 are formed by marine deposit of the Paleozoic, Triassic and Tertiary periods, 

 cretinism has been etiologically referred to peculiarities of the soil and to the 

 drinking water derived from these geological strata. That there is some truth in 



Fig. 505.- 



-Cbetin before (A) and after (B) Treatment with 

 (Nicholson, in Arch. ofPed., June, 1900.) 



's Thyroid. 



this explanation is shown by the fact that the introduction of fresh water from 

 other sources has eradicated this disease in at least some of these districts. More- 

 over, it is a matter of common experience among these people that the drinking 

 of water from so-called ''goiter-springs" gives rise to myxedematous symptoms 

 within a short time, while filtered or boiled water does not.^ 



(b) Myxedema. — The extirpation or atrophy of the thyroid gland in adults is 

 soon followed by symptoms such as have just been described. The skin becomes 

 thickened, swollen and dry and yields mucin when extracted with alkali. The hair 

 becomes coarse and scanty. There is also present a general fatigue, a mental 

 apathy, and a tendency to an abnormal deposition of fat. The nitrogen metab- 

 olism is reduced. 



1 Bircher, Zeitschr. fiir exp. Path, und Ther., ix, 1911. 



