236 PRACTICAL HISTOLOGY. 



and placing the piece thus distended in a beaker 

 containing some of the same mixture. After twenty- 

 four hours the tube is slit open, and transferred to 

 spirit for two or three days. The sections are to be 

 made across the length of the tube, and stained and 

 mounted in the ordinary manner. 



Preparation 14, Epithelium of ureter. To 

 study the separated epithelial cells a piece as fresh 

 as possible is cut open, pinned out on a cork with 

 the inner surface uppermost, and immersed in J per 

 cent, bichromate of potash solution for from twenty- 

 four to forty-eight hours. Some of the epithelium 

 is then scraped off with a spear-shaped needle or the 

 end of a scalpel, and is broken up in a drop of water. 

 After the addition of a piece of hair to the fluid 

 the cover-glass may be applied, and the preparation 

 examined with a high power. If it prove successful, 

 with many of the epithelial cells fully separated, it 

 may be permanently preserved. With this object 

 the cells should first be stained, by allowing weak 

 logwood solution to run under the edge' of the cover- 

 glass. The logwood is to be followed by a drop of 

 glycerine applied at the same edge; and, when the 

 glycerine has become diffused underneath, all that 

 is necessary is to cement the cover-glass. 



THE BLADDER. 



The urinary bladder, both for sections and teased- 

 out preparations, is prepared by exactly the same 

 methods as the ureters. To distend it a glass canula, 

 connected by an India-rubber tube with a bottle 

 containing the chromic fluid, is tied into the urethra. 

 The organ must not be over-distended, but only 

 moderately filled. Any urine which it may contain 

 should first be allowed to run out through the 

 canula. 



