74 



THE HORSK. 



PHARYNX— the back part of the mouth and above the first rings of 

 the gullet. It is common to the functions of respiration and digestion; 



I,ARYNX— the complicated structure situated at the top of the wind- 

 pipe, and just back of the root of the tongue. It may be considered a 

 box which opens into and is continuous with the wind-pipe: 



WIND-PIPE OR TRACHEA— the air tube consisting of rings of 

 cartilage which extends downward from the larynx to opposite the 

 fourth or fifth dorsal vertebra; 



BRONCHI — the two parts into which the wind pipe divides. The 

 one going to the right lung is called the right bronchus, the one to the 

 left lung is the left bronchus; 



BRONCHIAI, TUBES— the division of the bronchi which penetrate 

 and carry air to all parts of the lungs; 



AIR-CEEI/S — the small recesses at the end of the bronchial tubes. 

 These are separated from each other by a delicate membrane, between 

 the layers of which lies the plexus formed by the pulmonary artery. 

 The blood is thus exposed to the air on two surfaces; 



IvXJNGS. — the bronchial tubes, the air-cells and plexus together make 

 up what is commonly called the lungs. There are two divisions, one 

 on the right and the other on the left; 



PEEURA — the thin double membrane that surrounds the lungs. 

 One layer of this membrane is attached to the lungs, the other to the 

 chest wall. This membrane secretes a fluid to lubricate their • surfaces 

 as they move one upon another; 



DIAPHRAGM. — the muscular division which separates the heart, 

 lungs, and large blood vessels from the stomach, liver, and intestines. 

 It is the muscle of inspiration. 



Causes of Diseases of Respiratory Organs. These organs 

 are more liable to disease than the organs connected with any other 

 functions of the body, and as nearly all are the results of carelessness it 

 is well to know and study causes. In the spring and fall when animals 

 are changing coats, there is a tendency to contract disease, and care 

 should be taken at these periods to prevent other exciting causes. 



Avoid badly ventilated stables. 



Avoid taking horse from pasture and putting in too warm a stable. 



Avoid cold, close, damp stables as well as hot, close, and foul 

 ones. 



Avoid changing from a hot to a cold stable. 



