CH. XXIII.] 



THE THYROID. 



331 



colloid material, epithelium cells, colourless blood-corpuscles, and 

 also coloured corpuscles undergoing disintegration. 



Function. It is difficult to state definitely the function of the 

 thyroid body ; it is one of those organs of great importance in 

 the metabolic round ; and its removal or disease is followed by 

 general disturbances. It no doubt forms an internal secretion ; 

 to this the colloid material mentioned contributes, as it is found in 

 the lymphatic vessels of the organ. 



a 



Fig. .105. Part of a section of the human thyroid, a, fibre"* capsule ; 6, thyroid veniclea 

 filled with, . colloid substance ; c, supporting fibrous tissue ; /, short columnar cells 

 lining vesicles ; /, arteries ; g, veins filled with blood ; h, lymphatic vessel filled with 

 colloid substance. (8. K. Alcock.) 



When the gland is diseased in children and its function 

 obliterated a species of idiocy is produced called cretinism. 



The same condition in adults is called myxcedema ; the most 

 marked symptoms of this condition are slowness, both of body and 

 mind, usually associated with tremors and twitchings. There is 

 also a peculiar condition of the skin leading to the overgrowth 

 of the subcutaneous tissues, which in time is replaced by fat; 

 the hair falls off, the hands become spade-like; the whole body is 

 unwieldy and clumsy like the mind. 



A similar condition occurs after the thyroid is completely re- 

 moved surgically ; this is called cachexia strumipriva ; this operation, 



