THE HORSE. 



137 



muscular fibres, the contents of the stomach are thus 

 J kept m a state of constant agitation, wWch is considered 

 pfavorable to their chemical solution. 



Q. Does absor2)tion of nutritious matter take place 

 in the stomach ? — A. Yes. A portion of the nutri- 

 tious matter dissolved by the gastric fluid is at once 

 absorbed into the blood-vessels of the stomach, and 

 never passes into the intestinal tube, nor into the special 

 lacteal system of vessels. 



Q. What term is appHed to the food after its reduc- 

 tion, in the stomach, to a puljjy mass ? — A. Chyme. 



Q. Gas is frequently evolved in the stomach and 

 intestines during digestion : how do you accomit for 

 this ? — A. It is owing to a disturbed or morbid condi- 

 tion of that process, and by no means a necessary at- 

 tendant upon healthy digestion. 



Q. Does violent exercise immediately after a foed 

 tend to retard the formation of chyme ? — A. It does. 

 The circumstances most favorable to perfect digestion 

 are, a short period of rest, followed by gentle exercise. 



Q. Does any portion of the food ever pass unchanged 

 through the pylorus along with the chyme P — A. Yes. 

 Whole oats are frequently found in the horse's excre- 

 ment. 



INTESTINES. 



Q. The aUment now bemg converted into chyme, 

 and havmg passed the pylorus, what becomes of it ? 

 — A. It enters the duodenum. 



Q. Having entered the duodenum, with what does 

 the chyme mingle ? — A. The biliary and jjancreatic 

 secretions. 



Q. What effect do they have on the gastric secretion 

 and the chyme ? — A. The biliary and pancreatic secre- 

 tions are supposed to contain an excess of alkaH ; this 

 neutrahzes the acid of the gastric juice, so that there is 

 no forther solution of albuminous compounds, but the 

 conversion of starch into sugar, which was interrupted 

 in the stomach, now recommences. 



Q. What are the uses of the bile ? — A. The chief, 

 uses of the bile appear to be those of a chemical agent 

 promoting the decomposition of the chyme, and also 

 stimulating the secretion of mucus, and the peristaltic 

 action of the intestines. * 



Q. AVhat effect has the pancreatic juice on chjme or 

 the elements of digestion ? — A. It forms an emulsion 

 with oil and fat. 



Q. The chyme, havuig been acted on by the preced- 

 ing secretions, what name is then given to it ? — A. 

 Chyle. 



Q. Describe the properties of chyle ? — J.. If chyle 

 be taken from the thoracic duct of an animal a few 

 hours after it has taken food, it has very much the 

 appearance of cream, being a thick fluid of an opaque 

 white color, without smell, and ha^ing a shghtly acid 

 taste, accompanied by a perceptible sweetness. It 

 restores the blue color of Htmus, previously reddened 

 by acetic acid, and appears, therefore, to contain a pre- 

 ponderance of alkah. When subjected to microscoijic 



examination, chyle is found to contain a multitude of 

 18 



globules, of smaller diameter than those of the blood, 

 and corresponding in size and appearance to those of 

 milk. In about ten minutes after it is removed from 

 the thoracic duct, it coagulates mto a stiff jelly, wliich 

 in the course of twenty-fom- hours separates into two 

 parts, prouding a firm and contracted coagulum, sur- 

 romided by a transparent colorless fluid. 



Q. What are the principal ingredients of chyle? — 

 A. A large proportion of albumen, a smaller one of 

 fibrin ; a fatty substance or emvdsion, which gives to 

 chyle the appearance of milk ; and several salts, such 

 as carbonate of potassa, mm-iate of potassa, and pro- 

 phospate of iron. 



Q. What change does the chyle undergo in its pas- 

 sage along the various vessels ? — A. Its resemblance 

 to blood increases in each of the successive stages of its 

 progress towards the heart and Imigs. 



Q. How are the chemical changes, and the contents 

 of the intestines propelled through the tract of the 

 ahmentary canal ? — A. By»the peristaltic action of the 

 muscular coat of the same. 



Q. What becomes of the chyle after it has been pre- 

 pared in the duodenum and fu'st intestines ? — A. It 

 is received by absorption into the lacteals, and by them 

 conveyed to the thoracic duct, which transmits it to 

 large veins in the vicinity of the heart. (See distribu- 

 tion of lymphatics.) 



Q. What do you understand by the " absorbent sys- 

 tem?" — A. The absorbent system of vessels consists 

 of two princijDal divisions, wliich may be compared to 

 two sets of roots jjroceeding from a common trunk ; 

 one of these commences upon the walls of the intes- 

 tines, and is termed the " lacteal " system ; whilst 

 the other takes its origin in various joarts of the sub- 

 stance of the organism at large, esj^ecially in the skin 

 and subcutaneous textures, and is known as the " lym- 

 phatic " system. 



Q. Where do the lacteals most numerously abound ? 



— ^. In the small mtestines, below the pomt at which 

 the Hver and pancreas chscharge their secretions. 



Q. Where do the lacteals commence ? — A. Near 

 the fi'ee extremities of the villi of the intestines. 



Q. In what way do they commence ? — A. It was 

 formerly supposed that they commenced by orifices 

 upon the internal surface of the intestine ; but Carpen- 

 ter, and other physiologists, contend that the lacteal 

 vessels form loops by anastomosis Mith each other, so 

 that they have no free extremity. 



Q. What are the functions of the large intestines ? 



— A. They are engaged m the conveyance and expul- 

 sion of feculent matter, and there are certain changes 

 which take place in their contents, in aid of the object 

 of nutrition, the exact nature of which has never been 

 clearly determined. Accorduig to the best authority, it 

 appears that some important changes are effected in 

 that enlarged portion of the canal, termed coecum, and 

 wliich has, by some, been regarded as a kind of sup- 

 plementary stomach, in which fresh chjTne is formed, 

 and fresh nutriment extracted from the materials that 

 have passed tlu'ough the small intestines. The large 



