39G ABSORPTION OF SOLUBLE CARBOHYDRATES. 



]f largo quantities of salts, with a high cndosmotic equivalent, are intro- 

 duced into the intestine, e.g., magnesium or sodium sulphate, these salts 

 retain the water necessary for their solution, and thus diarrhoea is 

 caused (Poiseuille, Buchheim). Conversely, when these substances are 

 injected into the blood a large quantity of water passes from the intes- 

 tine into the blood, so that constipation occurs, owing to dryness of the 

 intestinal contents (Aubert). [M. Hay concludes from his experi- 

 ments (p. 320), that salts, when placed in the intestines, do not 

 abstract water from the blood, or are themselves absorbed, in virtue of 

 an endosmotic relation being established between the blood and the 

 saline solution in the intestines. Absorption is probably due to 

 filtration and diffusion, or processes of imbibition other than en- 

 dosmosis, as yet little understood. The result obtained by Aubert, 

 which is not constant, is mostly caused by the great diuresis which 

 the injected salt excites.] 



Numerous inorganic substances, which do not occur in the body, are absorbed by 

 endosmosis from the intestine, e.g., dilute sulphuric acid, potassium iodide, 

 chlorate, and bromide and many other salts. 



(2.) The soluble carbohydrates, such as the sugars of which the 

 chief representative is grape-sugar, with a relatively high endosmotic 

 equivalent. Cane-sugar is changed by a special ferment into invert 

 sugar, which is a mixture of grape-sugar and Isevulose (p. 370). 

 Perhaps a very small proportion of the cellulose is changed into 

 grape-sugar. The absorption appears to take place somewhat slowly, 

 as only very small quantities of grape-sugar are found in the chyle- 

 vessels or the portal vein at any time. According to v. Mering, the 

 sugar passes from the intestine into the rootlets of the portal vein ; 

 dextrin also occurs in the portal vein. When the blood of the portal 

 vein is boiled with dilute sulphuric acid, the amount of sugar is in- 

 creased (Naunyn). The amount of sugar absorbed depends upon 

 the concentration of its solution in the intestine; hence, the amount 

 of sugar in the blood is increased, after a diet containing much 

 of this substance (C. Schmidt and v. Becker), so that it may appear 

 in the urine, in which case, the blood must contain at least 0'6 per 

 cent, of sugar (Lehmann and Uhle). A small amount of cane-sugar 

 has also been found in the blood (Cl. Bernard, Hoppe-Seyler). The 

 sugar is used up in the bodily metabolism ; some of it is perhaps 

 oxidised in the muscles (Zimmer). 



(3.) The peptones have a small endosmotic equivalent (Funke), a 2-9 

 per cent, solution = 7-10. Owing to their great diffusibility, they are 

 readily absorbed, and they are the chief representatives of the proteids 

 which are absorbed. The amount absorbed depends upon the concen~ 



