106 ENDOSMOSIS AND EXOSMOSIS. 



ous mathematical and physical proof. The views I am here presenting 

 enable us to include the pressures between solids and liquids, the rise or 

 depression of liquids in capillary tubes, and the phenomena of chemical 

 affinity in the same general expression. And such a co-ordination is the 

 more valuable, since there has been a disposition among physiologists to 

 regard the introduction of material through the pores of organized textures 

 as dependent on some ill-defined or mysterious principle. 



The phenomena of endosmosis, first brought to general notice in the 

 Endosmosis case of liquid substances by M. Dutrochet, may be explain- 

 and exosmosis. e( j as follows : If some alcohol be placed in a bladder, the 

 neck of which is tightly tied, and the bladder be sunk in a vessel of 

 water, a percolation ensues, so that the bladder distends to its utmost 

 capacity, and might even be burst. Or, which is a better method of 

 showing the result, if, instead of tying the mouth of the bladder, a glass 

 tube, open at both ends, and a foot or two long, be fastened into it with- 

 out leakage, as the water introduces itself through the pores of the blad- 

 der to mingle with the alcohol, the liquid rises in the glass tube, sup- 

 posed to be left in a vertical position, and, when it has reached the top of 



it, overflows. To express this inward pas- 

 sage of the water the term endosmosis was 

 introduced, and since a little of the alcohol 

 simultaneously passes outward to mix with 

 the water, it is said to exhibit exosmosis. 



In Fig. 40 is represented the endosmome- 

 ter of Dutrochet. It consists of a small blad- 

 der, #, tightly tied to a tube, d, which is open 

 at both ends, and bent, as seen in the figure 

 at c ; the bladder being completely filled with 

 alcohol, and the tube to some such point as 

 d, the arrangement is to be placed in a ves- 

 sel of water, e e; almost immediately the level 

 of ^ jig^ w {\\ fa seen to be rising, the 

 bend of the tube is reached, and one drop after another falls from the open 

 end into the glass, b. And this continues until the liquids inside and 

 outside of the bladder are uniformly commingled. 



It is to be regretted that the terms endosmosis and exosmosis have 

 These move- "been accepted by physiological writers, for in these results 

 ments are de- fa QrQ ^ nothing more than what we* should expect from the 



pendent on ca- . , ^ .,, . mi e 



piliary attrac- known principles of capillary attraction. The pores 01 a 

 tlon - bladder, or of any other such organic texture, are nothing but 



short capillary tubes into which water readily finds its way, because it 

 can wet the substance surrounding the pore. If the bladder be distended 

 with air, and sunk under water, although the water will fill the pores, it 



