DIGESTION OF A MEAL. 349 



From such a meal we may first separate the elastin, cel- 

 lulose, and calcium sulphate, as indigestible and passed out 

 of the Body in the same state and in the same quantity as 

 they entered it. Then come the salines which need no 

 special digestion, and, either taken in solution or dis- 

 solved in the saliva or gastric juice, are absorbed from the 

 mouth, stomach and intestines without further change. 

 Cane and grape sugars experience the same fate, except 

 that any cane sugar reaching the intestines before absorp- 

 tion is liable to be changed into grape sugar by the succus 

 entericus. Calcium phosphate will be dissolved by the 

 free acid in the stomach, yielding calcium chloride, which 

 will be absorbed there or in the intestine. Starch will be 

 partially converted into various sugars during mastication 

 and deglutition, and the sugars will be absorbed from the 

 stomach. A great part of the starch will, however, be passed 

 on into the intestine unchanged, since the action of the 

 saliva is suspended in the stomach; .and its conversion will 

 be completed by the pancreatic secretion, and by the ptyaKii 

 of the saliva, which will recommence its activity when the 

 chyle becomes alkaline. | The various proteids will be par- 

 tially dissolved in the stomach and converted into peptones, 

 which will in part be absorbed there; the residue, with the 

 undigested proteids, will be passed on to the intestines. 

 There the bile will precipitate the peptones and parapep- 

 tones and, with the pancreatic secretion, render the chyme 

 alkaline, and so stop the activity of the gastric pepsin. The 

 pancreatic secretion will, however, redissolve the precipi- 

 tated peptone, and the unchanged proteids and parapeptone> 

 and turn the latter two into peptones; these will be absorbed 

 as they pass along the small intestine; a small quantity per- 

 haps passing into the large intestine, to be taken up there. 

 The fats will remain unchanged until they enter the small 

 intestine, except that the proteiJ. cell- walls of the fats of- 

 the beefsteak will be dissolved away. In the small intes- 

 tine these bodies will be partially saponified, but most will 

 be emulsified and taken up into the lacteals in that condi- 

 tion. Gelatin, from the white fibrous tissue of the beef- 



