THE DIGEbTIVK SYSTEM 



87 



of j!;lan(l-likt' tissue extcndinu; the entire length of the trachea. It 

 atrophies rapidly after liirth, and appears to play a function only 

 during the development of th{^ fetus. As a food it is considered 

 by many a delicacy, and is known as the "sweetbread." In ani- 

 mals castrated early it atrophies much slower than in stallions. 



Fig. 2o. — External surface of spleen: a, Dorsal extremity or base; 6, c, 

 anterior and posterior basal angles; d, anterior border; e, apex; 1, 2, 3, impres- 

 sions of last tliree ribs. (Sisson, Anatomy of Domestic Anmials.) 



The adrenals are paired ductless glands situated in contact 

 with each kidney (see Fig. 29). They are about 3 inches long and 

 U inches wide. Rapid death follows their removal, due to inter- 



