PULMONARY GLANDS 473 



PULMONARY GLANDS, ETC. 



In connection with the lungs ai*e three bodies, the uses of two of which 

 are not very clearly made out. These are the thyroid body, just below the 

 larynx ; the thymus gland, chiefly developed in the fcetus ; and the bron- 

 chial glands, which are merely lymphatic glands of the usual character, 

 situated around the principal divisions of the bronchi. 



The thyroid body is not very fully developed in the horse, and has little 

 interest connected with it, seldom being enlarged, as in the dog and in the 

 human species. It consists of two oval masses, about the size of an egg, 

 lying on each side of the trachea, just beneath the larynx, and connected 

 by a band or middle lobe. The use of the thyroid body is not 

 ascertained. 



Just within the thorax, and in close contact with the trachea, a some- 

 what similar body to the preceding is met with in the fcetus and young 

 foal ; but it soon wastes away as the young animal grows up. This is the 

 thymus gland (known to cooks as the sweetbread), resembling in shape the 

 thyroid body, but of a paler colour. Like it, the use of this gland is 

 not fully known ; but in structure it is more like the conglomerate 

 glands, and Sir Astley Cooper, who examined it most minutely, supposed 

 that it is intended " to prepare a fluid, well fitted for the fcetal growth 

 and nourishment, from the blood of the mother, before the birth of the 

 foetus." 



The bronchial glands are merely lymphatic glands, similar to those in 

 other parts of the body, and grouped around the large bronchial tubes. 

 They are of a greyish coloui*, stained with black in patches. 



