Columnar Epithelium. 63 



Shed skin of newt. This makes the best preparation 

 of surface epithelium. Place a newt in a glass jar of 

 water, and in three or four days it will he found that 

 it has shed the entire outer layer of epithelium as a con- 

 tinuous skin ; unroll it carefully, and cut into small 

 pieces, stain with logwood and mount in glycerine. 

 The staining will be facilitated by first placing it for 

 a short time in slightly acidulated water. Seal with 

 Hollis' glue, and examine with a low power. The 

 outlines of the cells and their nuclei will be very well 

 shown. 



Make a vertical section of skin prepared in chromic 

 acid mixture (wherever this mixture is mentioned, solu- 

 tion No. 1, p. 11 is meant). Stain in logwood and 

 mount in Canada balsam. 



Observe the different layers of cells, and with a high 

 power seek for the prickle cells of the Eete Malpighi. 

 These are, however, better seen in some epithelial 

 Cancers. 



COLUMNAE EPITHELIUM. 



Take the stomach of a newt or salamander prepared 

 in solution of chromate of ammonia (page 13), and wash 

 well until no colour comes away, place the whole in a 

 dilute solution of picro- carmine, about 15 drops to a 

 watch glass of distilled water, and let it remain until it 

 has taken on a deep red colour, then remove and wash 

 off the excess of colouring matter ; scrape off a little of 

 the surface material from the inside of the stomach, 

 and tease out gently on a slide in a drop of glycerin, 

 cover and examine. 



