URINARY SYSTEM. 473 



physiological point of view this epithelium is remarkable for 

 its impermeability ; it abso- 

 lutely opposes the transmis- 



* -i 



sion of liquids. A solution 

 of belladonna may be kept 

 in a perfectly healthy bladder 

 for a long, time, without risk 

 of poisoning from atropine ; 

 so, also, may solutions of 

 opium, without danger of 

 opium poisoning. But if the 

 epithelium is diseased, ab- 



sorption immediately occurs ; 128 . _ Epithelium of the bladder .* 

 and, as an example, when 



dilute alcohol is injected into the bladder in which there ex- 

 ists catarrhal inflammation, symptoms of alcoholic intoxica- 

 tion are manifested. The vesical epithelium even for some 

 hours after death preserves its vitality and consequently its 

 impermeability. If ferro-cyanide of potassium be injected 

 through a tube, thus preventing contact with the urethral 

 mucous surface, into the bladder of an animal which has just 

 been killed, then the bladder be exposed and a ferric salt 

 placed upon the outside of its w r alls, no Prussian blue will be 

 seen. This experiment shows that the two salts, which in 

 contact would produce Prussian blue, are separated by an 

 impassable barrier, viz., the epithelium. Yet if by means of 

 a wire the epithelial coat on the inside of the bladder be 

 scratched or destroyed at this point, Prussian blue will be 

 immediately formed. This opposition, then, to the passage 

 of liquids results solely from the presence of the epithelium. 1 

 The muscular fibres of the bladder are smooth, and 



1 For a further verification and elucidation of the above statement 

 the reader is referred to Ch. Robin, " Legons sur les Humeurs." 

 1867, p. 22. Also, see J. J. C. Susini, " De I'lmpermeabilite de 

 1'Epitheliuin Vesical." These de Strasbourg, 18 J7, No. 30. The 

 epithelium of the urethra being much less resisting, and possessing 

 a different character (columnar and pavement cells), permits ab- 

 sorption. (See Ailing, These de Paris, 1871.) 



* <7, Voluminous cell, with the edges notched ; smaller spindle-shaped cells 

 are attached to these edges. 6, Analogous cells ; the most voluminous has two 

 nuclei, c, A still larger cell, irregularly quadrilateral, with four nuclei, d, 

 Analogous cell, as seen in front, with two nuclei, and pitted, the pits correspond- 

 ing to the notches of the edges, above. (Virchow. "Path. Cell.," and "Archiv. 

 fur Pathol. Anat." Vol. ill. .Tab. 1, Fig. 8.) 



