33 



The lungs, the essential organs of respiration, are spongy 

 organs of a conical shape, and are situated in the thoracic cavity, 

 being very light and porous. (Healthy lungs float in vs^ater. ) 



The diaphragm or midriflE is the muscular partition which 

 separates the thorax from the abdomen. 



DIGESTIVE ORGANS. 



The digestive organs consist of the alimentary canal and its 

 accessories, by which the alimentary matter (food) is subjected 

 to the special actions which adapt it for the purpose of nutrition. 



Each division is provided vyith accessories; the preparatory 

 with the teeth and salivary glands, and the essential organs vsrith 

 the pancreas, liver, spleen, etc. 



The esophagus, or gullet, is a musculo-membranous, cylin- 

 drical canal passing from the pharynx to the stomach, through 

 which the food reaches the latter. 



The stohiach is a division of the alimentary canal, continuous 

 with the esophagus and small intestines, where the food is con- 

 verted into chyme by maceration and the action of the gastric 

 juice ; it is very small in the horse in proportion to his size. It 

 lies in the abdominal cavity just behind the liver. Its internal, 

 or mucous, coat is divided into right and left portions, the latter 

 is the cutaneous portion and is continuous with the mucous mem- 

 brane of the esophagus, which it resembles in structure and 

 appearance, being of a pale white color. The right portion, the 

 villous, or true digestive coat, is reddish in color, soft, very vas- 

 cular, and velvety looking. 



The capacity of the stomach is from 3 to 33^ gallons. 



The intestines are divided into large and small. The small 

 intestines are continuous with the stomach, rather more than an 

 inch in diameter and aboiit 73 feet in length. The large intes- 

 tines, measuring about 32 feet in length, extend from the termi- 

 nation of the small intestines to the anus, and may be regarded 

 as consisting of four parts, the caecum, great colon, floating 

 colon, and the rectum. 



The anus is the posterior opening of the alimentary canal, 

 being below the root of the tail. It forms a round projection, 

 which becomes less prominent with age. 



The intestines are supported throughout their entire length by 

 strong bands of fibrous tissue extending from the backbone. 



