184 THE SHEPHERD'S MAHTJAL. 



another from which flows the secretion of the pancreas of 

 sweet-bread. This fluid is slightly alkaline and very similar to 

 the saliva. Its office is supposed to be to change the undissolved 

 starch in the chyme into sugar, and to form an emulsion with the 

 oil or fat of the food, and prepare it for absorption directly into 

 the blood or into the lacteals. The office of the gall is to neutral- 

 ize the acidity of the chyme derived from the gastric juice, which 

 is an acid fluid, to assist in the transformation of starch into su- 

 gar, and the absorption of oil or fat. It is the chief agent in 

 changing the chyme of the stomach into the chyle, which is the 

 perfected source of nutrition of the blood. The perfect action of 

 the liver is therefore absolutely necessary to the sustenance and 

 the life of the animal. The quantity of gall secreted by the liver 

 of the sheep every twenty-four hours is from 3 to 5 pounds. The 

 whole of this, however, is not destroyed in the performance of its 

 office, but a large portion is taken into the system in the circula- 

 tion, the surplus being regained from the blood by the secreting 

 cells of the liver and again returned for duty to the intestines. 

 Another office of the liver is to prepare crude albuminous matter 

 of the blood for final absorption into it. It is also able to form 

 sugar from other carbonaceous matters conveyed to it in the chyle 

 absorbed by the lacteal vessels. Thus the liver acts as a filter, in 

 separating detrimental matters from the blood, besides supplying 

 a necessary agent in digestion, as well as for respiration. Its im- 

 portance in the animal functions cannot be over-estimated. 



The lacteals are a series of small absorbent vessels which form a 

 net-work in connection with the coats of the intestines, and pro- 

 ceed to the thoracic duct, where they terminate. They exist much 

 more numerously in connection with the small intestines than 

 with the lower ones. Their chief seat is the mesentery, which is 

 the thin membrane which supports the small intestines. The lac- 

 teals enter the numerous glands of the mesentery, and pass 

 through them, uniting to form larger vessels and becoming fewer 

 and fewer in number, being finally reduced to two or three ducts 

 which end in the thoracic duct. The lacteals absorb the chyle, 

 which is presented to them in the intestines, convey it to the glands 

 in which it is enriched and perfected, and thence convey it to 

 the vessels which terminate in the duct from which the new nutri- 

 tive matter is poured into the large vein near its junction with the 

 heart, to enter into the circulation. 



The chyle is very similar in its composition to the blood, differ- 

 ing from it chiefly in the absence of coloring matter, or the red 

 globules which give the color to the blood. It coagulates ou 



