CHAPTEE XXII. 



THE DUCTLESS GLANDS. 



THE THYROID GLAND. 



OF the function of the thyroid gland very little is known. Its 

 removal leads sooner or later to the death of the animal. This 

 is proceeded by various symptoms of nerve irritation, and in man 

 by the development of marked anaemia, impairment of the mental 

 powers, general prostration, and curious trophic disturbances of 

 the skin, which are associated with an increased development of 

 the subcutaneous connective tissue and a coincident increase in 

 the amount of mucin. As a result the skin appears swollen and 

 oedematous, constituting the condition known as myxcedema. Sim- 

 ilar results occur if from any cause the gland atrophies. If, how- 

 ever, the resection of the gland is partial, deleterious results do 

 not necessarily follow. It is thus manifest that the function of the 

 organ is a most important one, and it is interesting to note that the 

 apparent antitoxic properties of the gland persist even after its 

 removal from the body and subsequent desiccation. The various 

 symptoms which have just been described as following extirpation 

 of the organ may thus be prevented by administration of the 

 dried gland, and in cases of atrophy a curative effect may similarly 

 be obtained. It is noteworthy, moreover, that the administration 

 of the substance has a marked effect upon the nitrogenous metabo- 

 lism of the body, which is distinctly increased, and, if continued, 

 emaciation results although an abundant amount of food is ingested, 

 and digestion and resorpiion remain unimpaired. In some instances 

 true diabetes develops. In addition, an increased pulse-rate and 

 heightened blood-pressure are commonly observed, and even sud- 

 den death may occur during the use of the substance. 



That these curious properties of the thyroid gland should also 

 find expression in its chemical composition suggests itself at once. 

 Numerous attempts have accordingly been made to isolate the 

 "active principle" of the organ, and to a certain extent these at- 

 tempts have been successful. Baumann and Roos thus succeeded 

 in isolating from the gland a substance which has manifestly the 

 same properties as the entire organ in preventing the deleterious 

 results which follow its extirpation or atrophy, and which also has 

 the same effect upon the circulation and the nitrogenous metabolism. 

 This substance Baumann termed thyroiodine, from the fact that it 

 contains iodine in organic combination. It is obtained by boiling the 



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