ABSORPTION BY THE SMALL INTESTINE. 255 



place to no inconsiderable extent in the stomach ; although it also 

 is carried on more energetically in the small intestine. All varie- 

 ties of sugar dextrose, lactose, saccharose, and maltose are 

 absorbed in the stomach, and this is also true of dextrin. Some 

 of the saccharose is inverted to dextrose and levulose in the 

 stomach, and doubtless absorbed in this form to some extent, 

 while the rest of it undergoes the same change in the small intes- 

 tine. It is essential, however, that the solution should be concen- 

 trated ; at least this is true of dextrose, of which very little is 

 absorbed until the concentration equals 5 per cent., and the rate 

 of absorption increases up to a concentration of 20 per cent. 

 Alcohol causes increased absorption of sugar, as it does of sodium 

 iodid, and doubtless for the same reason. Taken as a whole, the 

 amount of the sugars absorbed from the stomach is probably not 

 great. 



Peptones. These are also absorbed from the stomach, though, 

 as in the case of dextrose, only when the concentration reaches 5 

 per cent., so that the absorption of peptones from the stomach is 

 relatively small. 



Fats and Oils. With the exception of the physical change, 

 due to the temperature of the stomach, by which the fats and oils 

 are rendered more fluid, and their probable splitting up into fatty 

 acids (p. 199), no change takes place in them, nor are they absorbed 

 to any extent whatever. 



Alcohol. The fact that alcohol is readily absorbed from the 

 stomach has been sufficiently dwelt upon (p. 161). 



From the above considerations it will be seen that gastric ab- 

 sorption is not a process of much importance ; indeed, the cases 

 of the entire removal of this organ, to which we have referred, 

 demonstrate that the exercise of what little absorptive power it 

 possesses, is unnecessary. We desire to direct special attention 

 to the fact that sodium iodid, dextrose, and peptones are more 

 readily absorbed when alcohol is also present. This empha- 

 sizes the view now held as to absorption, that it is not a mere 

 matter of osmosis, but is due to an actual selective power of 

 the epithelial cells, and that this is more actively exercised under 

 the stimulating action of alcohol or other substances having like 

 power. 



Absorption by the Small Intestine. It is from the 

 cavity of the small intestine that the greater part of absorption 

 takes place, the products of digestion passing into the villi, a part 

 entering the capillary blood-vessels and reaching the liver through 

 the portal vein ; while another part enters the lacteals, and passes 

 on into the thoracic duct, from which it is discharged into the 

 blood-vascular circulation. While osmosis is doubtless one of the 

 factors in this process, still the selective power of living cells 

 is much more potent. 



