THE LYMPHATIC SYSTEM. 313 



absorb water more abundantly than a saline solution ; and if a partially 

 dried membrane be placed in a saturated solution of sodium chloride, 

 owing to its rapid absorption of the water, a part of the salt will be 

 left behind and deposited in a crystalline form on its surface. 



The position of the membrane exerts a similar influence, owing to 

 a difference of absorbing power in its two surfaces. Matteucci found 

 that, in using the mucous membrane of the ox-bladder with water and 

 a solution of sugar, if the mucous surface of the membrane were in 

 contact with the saccharine solution, the liquid rose in the endosmome- 

 ter between 80 and 113 millimetres in two hours. But if the same 

 surface were turned toward the water, the rise of the column of fluid 

 was only between 63 and 72 millimetres in the same time. 



Another important condition is the constitution of the two liquids 

 and their relation to each other. Dutrochet measured the force with 

 which water passes through the mucous membrane of the ox-bladder, 

 into different solutions of similar density, with the following result : * 



EXDOSMOSIS OF WATER TOWARD DIFFERENT LIQUIDS. 



With solution of Intensity of endosmosis. 



Gelatine ..... ... 3 



Gum . . 5 



Sugar 11 



Albumen .... .12 



As a general rule, when the liquids employed are water and a saline 

 solution, the more concentrated the solution, the more active is endos- 

 mosis ; a larger quantity of water passing toward a denser liquid than 

 toward one which is more dilute. But the above table shows that 

 endosmosis will vary in activity with solutions of different substances, 

 even though they may be of the same density ; and when the two 

 liquids used are alcohol and water, endosmosis takes place from the 

 water to the alcohol, that is, from the denser liquid to the lighter. 



When two different liquids, therefore, are placed in contact with the 

 membrane, there is usjially a comparatively rapid endosmosis in one 

 direction and a comparatively slow exosmosis in the other, according 

 to the rates at which the two liquids traverse the membrane. But in 

 some cases there may be endosmosis without exosmosis. Thus when 

 water and albumen are employed as the two liquids, while the water 

 readily passes inward through the membrane, the albumen does not 

 pass out. If an opening be made in the large end of a fowl's egg, so 

 as to expose the shell-membrane, and the whole immersed in water, 

 endosmosis will take place freely from the water to the albumen, so as 

 to distend the membrane and make it protrude, like a hernia, from the 

 opening in the shell. But the albumen does not pass outward, and 

 the water remains pure. After a time the pressure from within, due 

 to the accumulation of fluid, becomes sufficient to burst the shell- 

 membrane, after which the two liquids mingle with each other. 



* In Matteucci, Physical Phenomena of Living Beings. Pereira's Translation. 

 Philadelphia, 1848, p. 48. 



