LECT. III. ENDOSMOSE. 45 



make you acquainted \vith another phenomenon, which, 

 although exclusively within the domain of physics, yet 

 nevertheless, by the physiological applications of which it 

 is susceptible, is really connected with the study of or- 

 ganized beings. I refer now to the phenomenon discovered 

 by Dutrochet,* and termed by him endosmose. It is the 

 mutual action of two liquids on each other when separated 

 by a membrane. Although its theory is not yet completely 

 known, the subject is nevertheless of the highest impor- 

 tance. 



I shall commence by explaining to you the fundamental 

 fact in its simplest form. Here is a glass tube whose 

 lower extremity, closed by a piece of bladder, is expanded 

 into the form of a funnel. This instrument is called an 

 endosmometer. 



If we pour into it an aqueous solution of either gum or 

 sugar, and then immerse the closed extremity in pure 

 water, we shall find that, notwithstanding the excess of 



* Dutrochet's first memoir on endosmose and exosmose was read to the 

 Academic Royale des Sciences, on the 23d of July, 1827 (see the Ann. de 

 Chim. et de Phys. torn, xxxvii. p. 393. 1827.) 



Ten years previously, my friend Mr. Porrett, the present treasurer of 

 the Chemical Society of London, had communicated to the editor of the 

 Annals of Philosophy (vol. viii. p. 74, for July, 1816) a paper on two 

 "curious galvanic experiments" oce of which was the production of en- 

 dosemose between two liquids separated by a membrane and subjected 

 to the action of voltaic electricity. He called the phenomenon, electro- 

 Jiltration; and asks, whether jointly with electro-chemical action, it is 

 not " in constant operation in the minute vessels and pores of the animal 

 system." 



M. Parrot, of St. Petersburgh, has' recently presented to the Academic 

 Royule des Sciences, an inaugural dissertation, published in 1803, giving 

 an account of ihe phenomena presented by two liquids of unequal density, 

 separated by a permeable organic diaphragm, and pointing out their ap- 

 plications to physiology and pathology. (Comptes rendus, torn. xix. pp. 

 607. 619. for Sept. 23d. 1844.) J. P. 



