474 ABSOKPTION. 



From the beginning of the present century, up to 1826, 

 several isolated observations were made on the passage of 

 liquids through membranes. In 1802, Parrot noted the 

 passage of water through the membranes of an egg which 

 had no calcareous covering ; 1 in 1816, Porrett noted that the 

 galvanic current was capable of causing water to pass through 

 an animal membrane ; 3 and finally, in 1822, Fischer, pro- 

 fessor at Breslau, actually constructed an endosmometer, and 

 noted the elevation of the liquid in the tube above the level 

 of the liquid in which the apparatus was placed. The experi- 

 ments of Fischer were more complete, and illustrated the 

 laws of endosmosis more fully, than is generally supposed. 

 Not only did he construct an endosmometer, closing the 

 lower portion of his apparatus with an animal membrane, 

 and noting the passage of pure water through the membrane 

 to a saline solution, but he described the exosmosis of 

 the saline solution, and observed that the currents continued 

 until both liquids became of equal density. He also noted 

 that the currents were active in proportion to the thinness 

 of the animal membrane used. 3 



To return to the observations of Dutrochet, it is univer- 

 sally acknowledged that he was the first to describe fully 

 and definitely the passage of liquids through animal mem- 

 branes, out of the body ; to show the influence of different 

 liquids used ; to measure the force of the different currents ; 

 and, finally, to give to these actions the names of endosmosis 

 and exosmosis. 4 He constructed an instrument known as 



1 PARROT, Phenomene frappant d^Endosmose dans P Organization animate. 

 Bulletin ScientifiquG de V Academic de St. Petersbourg, 1840, tome vii., p. 346. 



2 PORRETT, Curious Galvanic Experiments. Annals of Philosophy, London, 

 1816, vol. viii.,p. 74. 



3 FISCHER, Ueber die Wiederherstellung eines Metalls durch ein anderes und 

 iiber die Eigenschaft der thierisclien JBlase Flussigkeiten durch sicli hindurch zu 

 lassen, und sie in einigen Fallen aw27i&m. GILBERT'S Annalcn der Physik, 

 Leipzig, 1822, Bd. kxii., S. 301. 



4 DUTROCHET, De I* Endosmose. Memoires pour servir d VHistoire Anato- 

 mique et Physiologique des Animaux, Paris, 1837, tome i., p. 1 et seq. 



Dutrochet was first led to study the phenomena of endosmosis by observing 



