Excretion. 69 



lungs, which are spongy organs of a rosy flesh color, some- 

 what marbled in appearance ; the right lung is some- 

 what larger than the left, the latter being encroached 

 upon by the heart. A healthy lung will float in water. 

 The lung substance in the natural state is very elastic 

 and requires plenty of room for expansion ; pressure on 

 the lung tissue, due to a lack of room, the result of such 

 causes as overfeeding, feeding bulky innutritions feed, 

 sometimes ends in rupture of some of the air cells; this 

 condition prevents the performance of the natural lung 

 work and as a disease is termed Heaves. 



In connection with the lungs the pleura, one of the 

 serous membranes, commands attention. The pleura has 

 two layers, one covering the lungs, the other lining the 

 inside of the ribs; between the two layers is a small space. 

 The two layers of the pleura, in health, glide over one 

 another without friction, being oiled by the secretions, as 

 a result of inflammation, the layers become dry and pain 

 is the result; later on an excessive discharge of fluid may 

 take place, constituting water in the chest (hydrothorax). 



