68 Veterinary Elements. 



Immediately below the larynx is the windpipe (tra 

 chea), a flexible tube made up of rings of cartilage, liga- 

 ments, etc. ; lying just above it is the gullet (esophagus). 

 The thyroids, little reddish round bodies on the sides of 

 the windpipe just below the jaws, are of interest, owing 

 to the scientific curiosity as to their functions, which up 

 to the present time are not known. Enlargement of 

 these glands occur in animals, the condition being known 

 as Goitre, very often a serious trouble in breeding ewes, 

 serious because the progeny of such ewes die at or soon 

 after birth. The thymus gland or sweetbread while well 

 developed in the young animal tends to disappear, shrivel 

 up, as the animal grows older. It is interesting to note 

 the demand for this gland, seventy cents a pound, whole- 

 sale, being obtained for it in Chicago that is, for calves 

 sweetbreads; two- year-old sweetbreads are not as valu- 

 able, they eventually turning into fat. 



The trachea or windpipe is located in the region of the 

 neck, and at its lower end enters -the chest cavity, where 

 it divides into smaller tubes (the bronchi), which again 

 divide into still smaller tubes (the bronchioles), these 

 end in little pockets or sacs (the air cells of the lung). 

 The mucus membrane of the trachea has numbers of 

 cells possessed of wavy tails, known as cilia. These cilia 

 have a continual motion from within outwards, so that if 

 mucous or some foreign particles get into the windpipe, by 

 the motion of these cilia, this material is thrown out. 



The blind pockets or air vesicles of the lungs are 

 formed of a very fine membrane surrounded by very 

 delicate blood vessels. These air cells, the small bron- 

 chioles, blood vessels and nerves go to make up the 



