THE ALIMENTARY CANAL. -27-5 



carried away by rupture of the glandular sac, or by absorption 

 into the neighbouring lymphatics. 



The liver has been termed a reticular gland, because its ducts 

 form a network at their origin. 



DIGESTIVE SYSTEM. 



The digestive organs comprise the alimentary canal and its 

 accessories, by which the alimentary matter is received and sub- 

 jected to specific actions, which adapt it for purposes of nutri- 

 tion. Digestion therefore embraces the collective operations and 

 changes which the food undergoes in the alimentary canal. 



The functional processes of digestion are Prehension, the 

 taking up of food, which is performed in the horse by the lips ; 

 Mastication, chewing, grinding ; and, simultaneously with this, 

 Insalivation, or mixing the ingesta with the fluid secretion of 

 the salivary glands ; Deglutition, or swallowing the prepared food 

 by means of the tongue, pharynx, and oesophagus; Chymincation, 

 or conversion of food in the stomach into a pultaceous chyme, 

 by maceration and the action of the gastric juice ; ChylifiC" 

 or conversion of the chyme into chvle, a change which takes 



tf / 



place in the duodenum, presumably by the agency of the biliary 

 and pancreatic secretions ; Absorption of the nutrient material 

 into the circulation ; and finally, Defecation or excretion, the 

 expulsion of residual inert matter. 



THE ALIMENTARY CANAL. 



The alimentary canal is a musculo-membranous tube extend- 

 ing from the lips to the anus ; its walls are composed of muscular 

 tissue, for the most part of the non-striated kind, and lined 

 throughout by mucous membrane. It consists of a continuous 

 series of tubes and cavities, the chief of Avhich are the Mouth, 

 Pharynx, (Esophagus, Stomach, and the Intestines. It may be 

 divided into three portions the preparatory, or ingestive, em- 

 bracing the mouth, pharynx, and oesophagus, in which the food 

 is prepared ; the essential, or digestive, including the stomach 

 and most of the intestines, where the food passes through various 

 changes, and is deprived of its nutritive portions ; and the 

 egestive, or expulsive portion, by which the residue is expelled 

 from the system. Each division is provided with accessories, the 



