PASSAGE OF LIQUIDS THROUGH MEMBRANES. 473 



minutes. This experiment was repeated upon other animals 

 and upon the carotid artery, with similar results. 1 These 

 observations are referred to in recent French works on phys- 

 iology, as the first experiments illustrating the operation of 

 imbibition in the process of absorption ; 2 but we cannot dis- 

 cover why they do not fully illustrate the passage of liquids 

 through the membranes which form the walls of the blood- 



o 



vessels. If they had been made after the experiments of 

 Dutrochet, instead of before, they would certainly have been 

 quoted as illustrations of endosmosis. 



As regards experiments on the passage of liquids through 

 membranes, out of the body, those made by the Abbe 

 Nollet, in 1748 (probably the first on record), are most strik- 

 ing, when brought in comparison with the illustrative experi- 

 ments made on endosmosis at the present day. 



In the course of a series of observations on the causes Of 

 the ebullition of liquids, ISTollet filled a vial about five inches 

 long with alcohol, covered it tightly with a moistened blad- 

 der, and immersed it in pure water. In five or six hours, he 

 found that the water had passed through the membrane to 

 the alcohol, and the bladder had become convex. It first 

 occurred to him that this might be due to a difference in the 

 temperature of the two liquids ; but the same phenomenon 

 was presented when the temperature of the liquids was the 

 same. On filling the vial with water and immersing it in 

 alcohol, the action was reversed, and the membrane became 

 concave. By a series of ingeniously contrived experiments, 

 he also ascertained that water could readily be forced through 

 a membrane, while alcohol passed through in small quantity 

 and only under great pressure. 3 



1 MAGENDIE, Memoire sur le Mecanisme de I 1 Absorption chez les Animaux d 

 Sang rouge ei chaud, lu d VAcademie des Sciences de Paris, octobre, 1820. 

 Journal de Physiologic, Paris, 1821, tomei., p. 1 et seq. 



2 MILNE-EDWARDS, Lecons sur la Physiologic, Paris, 1859, tome v., p. 25; and 

 LONGET, Traite de Physiologic, Paris, 1861, tome i., p. 381. 



3 NOLLET, Recherches sur les Causes du Bouillonnement des Liquides. 

 Memoir es de VAcademie Royale, Paris, 1748, p. 101 et seq. 



