84 



in the various clumps will appear cells on end showing the tops or 

 bases, and other clumps will show the cells in profile. 



Tap the cover gently with a needle-holder or other light object 

 in order to separate the cells from each other more completely. 

 Many fully isolated cells as well as cells in groups will be seen. 

 Examine carefully. 



§ 6. Staining. Scrape gently the epithelial surface in a fresh 

 spot and place the scrapings on the slide in a drop of eosin (§ 94) or 

 a mixture of eosin and methylgreen (§ 92). Mix well so that the 

 stain can penetrate. If for temporary examination, cover immedi- 

 ately and examine as before. 



§ 7. Permanent preparations. If a permanent mount is de- 

 sired, (a) allow the above mixture to stand for 5-10 minutes ; drain 

 off the stain, collecting the fragments carefully at one side ; add a 

 small drop of glycerin or glycerin-jelly (§§ 104, 105) ; cover and 

 examine, tapping the cover gently as before, if necessary, in order 

 to separate the cells more thoroughly. Unstained preparations may 

 be mounted in the same manner. 



(^) The following method will also give satisfactory stained 

 preparations. Place a small mass of cells in a drop of alum carmine 

 and eosin glycerin (§ 156) ; cover and isolate the cells by tapping 

 gently on the cover-glass as before. Clean and seal the preparation 

 (§ no). 



If it is desired to make a permanent mount of a preparation 

 already covered and examined, place a drop of glycerin at the edge 

 of the cover, apply to the opposite side of the cover a piece of blot- 

 ting paper or filter paper, and by absorbing the fluid— dissociator or 

 stain — under the cover, cause the glycerin to flow under to take its 

 place. 



Seal the preparation (§ no) ; it is usually better, however, to 

 allow a glycerin or glycerin-jelly mount to stand for a day, being 

 careful that it is not touched, and then seal. 



§ 8. Formaldehyde Dissociator. Formula : 40% formal- 

 dehyde (formalin), 2 c. c. ; normal salt solution, 1,000 c. c. (i. e., 

 .08% sol. of formaldehyde in normal salt solution). This is a good 

 general dissociator and as such maybe employed instead of Miiller's 

 fluid dissociator. It is especially serviceable in the isolation of the 

 nerve cells of the brain and spinal cord. 



