THE THYROID AND PARATHYROID. 341 



identical with that contained in the vesicles, has been found in 

 the lymphatics. 



The arteries which supply the thyroid body are the superior 

 and inferior thyroid, and sometimes the thyroidea media or ima, 

 an occasional branch of the innominate or aorta. 



The nerves are from the middle and inferior cervical ganglia 

 of the sympathetic. 



Functions. In recent years the physiology of the thyroid 

 body has received a great deal of attention, and important addi- 

 tions have been made to the knowledge of its function by a study 

 of (1) the effects of its disease and (2) of its removal. 



Cretinism. In some parts of Switzerland and elsewhere on the 

 Continent there exists a disease characterized by a swelling of the 

 thyroid, termed goiter, together with "stunted growth, swelled 

 abdomen, wrinkled skin, wan complexion, vacant and stupid 

 countenance, misshapen cranium, idiocy, and comparative insensi- 

 bility." This disease is cretinism, and those suffering from it are 

 cretins. This condition is accompanied by disease of the thyroid, 

 as manifested by the goiter. 



Myxedema. A similar condition is sometimes seen in which 

 the striking characteristic is the appearance of the skin, which 

 resembles edema ; and the material which is deposited in the con- 

 nective tissue was thought to be mucin, hence the name myxedema. 

 Although there is more mucin than in ordinary connective tissue, 

 still the material here is not altogether mucin, nor is it true edema 

 /. <?., a dropsical effusion into the cellular tissue but a hyper- 

 plastic and modified connective tissue. In addition to this condi- 

 tion of the skin there is also a slowness of gait, an apathy of mind, 

 and sometimes tremors and twitchings of muscles. 



Operative Myxedema. When the thyroid gland becomes 

 enlarged, this may be due to a hypertrophy of the vesicles, paren- 

 chymatous goiter, or of the connective tissue, fibroid goiter ; or the 

 vesicles may form cysts, cystic goiter, or the blood-vessels may be 

 dilated, pulsating goiter, or the vessels may be enlarged, and with 

 this a prominence of the eyes, palpitation of the heart, and a quick 

 pulse, exophthalmic goiter or G raves' s disease. For goiter, one of 

 the methods of treatment is the removal of the gland ; when this 

 is practised, a condition of myxedema results, operative myxedema. 

 The removal of the thyroid, thyroidectomy , has been performed 

 upon dogs with a fatal result in all cases, occurring so soon after 

 the operation within fourteen days that the changes in the skin 

 have no time to take place, but tremors, spasms, and convulsions 

 occur. One remarkable fact was discovered by Schiff, who per- 

 formed as many as sixty thyroidectomies on dogs namely, that if 

 a portion of a thyroid was, before the operation, grafted under the 

 skin or into the peritoneal cavity, the symptoms described did not 

 occur, and the animals did not die. Horsley removed the thyroid 

 from monkeys, with the result of producing myxedema. 



