336 



THE DUCTLESS GLANDS 



[en. xxm. 



or cubical cells. These vesicles are filled with transparent colloid 

 nucleo-albuminous material. The colloid substance increases with 

 age, and the cavities appear to coalesce. In the interstitial connec- 

 tive-tissue is a round meshed capillary plexus, and a large number of 

 lymphatics. The nerves adhere closely to the vessels. 



In the vesicles there are, in addition to the yellowish glassy colloid 

 material, epithelium cells, colourless blood-corpuscles, and also coloured 

 corpuscles undergoing disintegration. 



It is difficult to state definitely the function of the thyroid body ; 



-FiG. 314. Part of a section of the human thyroid, a, fibrous capsule; b, thyroid vesicles filled with, 

 e, colloid substance ; c, supporting fibrous tissue ; d, short columnar cells lining vesicles ; J, 

 arteries; g, veins filled with blood; h, lymphatic vessels filled with colloid substance. (S. K. 

 Alcock.) 



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 men- 

 tioned contributes, as it is found in the lymphatic vessels of the 

 organ. 



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 



