THE DUCTLESS GLANDS 



255 



into actual contact with the cells and fibers of a tissue. 

 The veins of the spleen unite to form the splenic vein, 

 which carries the blood into the portal vein and so to the 

 liver. 



367. Functions of the Spleen. Little is yet positively 

 known as to the functions of the spleen. That the organ 

 has some connection with digestion is shown by its enlarge- 

 ment as soon as gastric digestion is completed. It has 

 also some close relation to the liver, and it is understood 

 to be engaged, like the lymphatic glands, in the manufac- 

 ture of white corpuscles. In some animals it forms the colored 

 corpuscles likewise, but we do not know whether that is 

 true of the human spleen. It is thought by some that the 

 spleen is the organ where the red corpuscles which are 

 worn out undergo disintegration, their coloring matter 

 being carried to the liver and there used to form the 

 coloring matter of the bile. 



368. The Thyroid Gland is a body whose two lobes lie on 

 the sides of the trachea (Fig. 117). The disease called 

 goiter is an enlargement 



and alteration of struc- 

 ture of the thyroid, and 

 the effects sometimes ex- 

 tend to the impairment 

 of muscular and nervous 

 activity and to a semi- 

 idiotic condition of mind, 

 resulting in death if the 

 whole gland is affected. 

 The diseased condition Fig. 117. Thyroid and thymus glands 

 may be relieved or cured of an infant - 



by grafting a portion of the thyroid gland from an 

 animal under the skin of the afflicted one, or by adding 



Thyroid Gland 



... Carotid A. 



-- Internal Jugular V. 



Trachea 



~ ~ Suspensory Ligament 

 -\--Innominate V. 



Thymus Gland 



-Lung 



