90 INTRODUCTION. 



All nutrimont of every kind being' extracted, and the residue 

 havin<r reached the last intestine, the rccluni, it is liurried on to be 

 txpclled. 



Several diseases to ^hich the intestines of cattle are exposed 

 havintr re^vrence to, or being seated in, dilTerent coats or niembranea 

 ol these vessels, it will be necessary to «^peak briefly of them. In 

 the first place, they are all wrapped up in a very thin membrane or 

 bag, yet one that possesses considerable strength, called the perito- 

 fieum. It secretes a serous fluid, and thus prevents friction in the 

 raiiiral motion of the bov/els over or among each other; and, encir- 

 cling them all, /* retains each pretty much in its place and restrains 

 too extensive or dangerous motion. The outer coat of the intestines 

 is composed of a reflection or expansion of this membrane, and is 

 liable to a peculiar inflammation. The second coat is musculnr, and 

 is composed of a double layer of fibres, by the action of which the 

 food is conveyed or pressed along the canal, and which is called the 

 perislaHic motion. The inner coat is the mucous one, so called from 

 the jelly-like substance by which it is covered ; called also the villous 

 coat, from its velvet-like construction. It is thickly set with innu- 

 merable glands pouring out this mucus, and it is the seat of inflam 

 mation in over-purging. 



The Mesentery, or that membrane by which the intestines are en- 

 folded from begiiming to end, and through the folds of which the 

 blood-vessels and nerves that supply the intestines, and the veins, 

 and the lacteals pass, is only a duplicature of the peritoneum. In 

 diflferent parts of the mesentery, various glandular bodies are seen: 

 they are tlie mesenteric glands, the precise use of which is not known, 

 except that they are connected with the passage of the chyle. The 

 enlargement or obstruction of them is sometimes attended with very 

 serious disease, and even with death. The nmenium, or caiil. is also 

 a portion of the peritoneum. The use of it has never been satisfacto 

 rily explained. 



The Liver is a large gland, of a dark-red colour, situated in the 

 belly on the right side, and secreting a bitter fluid named hile, oi gall. 

 It receives the blood that returns from all the contents of the belly, 

 and which is probably so loaded with carbon that it could not all be 

 discharged by the lungs; the quantity of atmospheric air thot can be 

 introduced into the lungs in the act of breathing not containing suffi- 

 cient oxygen for the purpose. The blood is, therefore, sent into ths 

 liver, where it undergoes a process of puriiication to a certain extent. 

 This inflammable matter, the carbon, is separated in the form of bile; 

 and when that is convej'^ed into the bowels, in order that it may be 

 expelled, it is rendered exceedingly useful there, either by separating 

 Ihe chyle, or quickening the passage of the food, or both. The yellows 

 in cattle is caused either by too great an increase of bile, or by oh' 

 struction of its passage into the intestines. In the first case the sur- 

 plus quantity is taken up by the absorbents, and enters in o the 

 t^irculation and tinges the blood yellow; and in the other case., accu* 



