THE LYMPHATIC SYSTEM. 309 



allowed to remain and soak in the fluids, after the column has risen 

 to a certain height in the upright tube, it begins to descend again 

 as soon as putrefaction commences, and the two liquids finally sink 

 to the same level. 



The next condition is the extent of contact between the membrane 

 and the two liquids. The greater the extent of this contact, the 

 more rapid and forcible is the current of endosmosis. An endos- 

 mometer with a wide mouth will produce more effect than with a 

 narrow one, though the volume of the liquid contained in it may 

 be the same in both instances. The action takes place at the 

 surface of the membrane, and is proportionate to its extent. 



Another very important circumstance is the constitution of the two 

 liquids, and their relation to each other. As a general thing, if we 

 use water and a saline solution in our experiments, endosmosis is 

 more active, the more concentrated is the solution in the endosmo- 

 meter. A larger quantity of water will pass inward toward a dense 

 solution than toward one which is already dilute. But the force of 

 endosmosis varies with different liquids, even when they are of the 

 same density. Dutrochet measured the force with which water 

 passed through the mucous membrane of an ox-bladder into differ- 

 ent solutions of the same density. He found that the force varies 

 with different substances, as follows i 1 



Endosmosis of water, with a solution of albumen . . 12 



sugar ... 11 



" " " gum ... 5 



" " " gelatine . . 3 



The position of the membrane also makes a difference. With some 

 fluids, endosmosis is more rapid when the membrane has its mucous 

 surface in contact with the dense solution, and its dissected surface 

 in contact with the water. With other substances the more favor- 

 able position is the reverse. Matteucci found that, in using the 

 mucous membrane of the ox-bladder with water ard a solution of 

 sugar, if the mucous surface of the membrane were in contact with 

 the saccharine solution, the liquid rose in the endosmometer between 

 four and five inches. But if the same surface were turned outward 

 toward the water, the column of fluid was less than three inches in 

 height. Different membranes also act with different degrees of force. 

 The effect produced is not the same with the integument of different 

 animals, nor with mucous membranes taken from different parts of 

 the body. 



1 In Matteucci 's Lectures on the Physical Phenomena of Living Beings. Philada., 

 1848, p. 48. 



