276 PHYSIOLOGY OF ALIMENTATION. 



ordinarily given is as follows: While the inorganic constitu- 

 ents of the blood may diffuse out into the lumen of the intes- 

 tine, the organic constituents (the albumin, globulin, etc.), 

 because of their colloidal nature, are practically unable to 

 do this. While colloids exert no great osmotic pressure they 

 nevertheless exert some, and so, even after all other osmotic 

 differences on both sides of the diffusing membrane have been 

 equalized, an excess of osmotic pressure must remain on the 

 side of the blood. This would then lead to the abstraction of 

 a small amount of water from the solution in the intestine 

 which would in consequence be rendered hypertonic. Salts 

 would then diffuse into the blood, then more water, until, 

 little by little, the whole would be absorbed. 1 



For a large number of salts the rate of absorption is propor- 

 tional to the velocity of their diffusion (HOBER 2 ). In the 

 following table are arranged a number of salts in the order of 

 their diffusion velocities. When arranged in the order of the 

 velocity with which these salts are absorbed from isotonic 

 solutions when equal amounts are introduced into closed 

 loops of intestine the grouping remains the same. 



Sodium chloride 



Sodium nitrate 

 Sodium lactate 



Sodium sulphate 



Sodium malonate 



Sodium succinate 



Sodium tartrate 



Sodium malate 



Magnesium chloride 

 Calcium chloride 



1 More detailed discussion of these still unsatisfactory theories of 

 absorption cannot be entered into here. See HOBER: Physikalische 

 Chemie d. Zelle u. d. Gewebe, Leipzig, 1902, p. 184; PFLUGER'S Archiv, 

 1898, LXX, p. 624. STARLING: Journal of Physiology, 1896, XIX, p. 

 313. KOVESI: Centralbl. f. Physiol., 1897, XI, p. 553. 



2 HOBER: PFLUGER'S Archiv, 1899, LXXIV, p. 246. Zelle und 

 Gewebe, Leipzig, 1902, p. 190. 



