ALIMENTARY TRACT AS AN ABSORPTIVE SYSTEM. 263 



tube T. If this cell is filled with a sugar solution, and the 

 whole is dipped into a second vessel, B, filled with water, the 

 sugar endeavors to pass out into the water (diffusion). This 

 movement is prevented, however, by the semipermeable 



V 



u 



Sugar 

 Solution 



Water 



FIG. 28. 



membrane and water is in consequence drawn into the 

 osmotic cell, which evidences itself by a rise of the meniscus 

 in the tube T. The water continues to enter the cell until 

 the hydrostatic pressure in the tube is equal to the osmotic 

 pressure in the cell. 



The reason why the water enters the cell, or, in general, 



