MOVEMENT 17 



the drying of the latter should be carried out as rapidly as 

 possible. 



(4) Place the cover-glass in Cornet forceps, and cover the 

 surface of the film with a few drops of the following mordant, 

 which must be filtered : 



A 20 per cent, solution of tannin . . . 10 cc. 



Saturated solution of ferrous sulphate . . 6 



Saturated alcoholic solution of fuchsin . . i 

 Warm the cover-glass, and allow the mordant to act for four 

 to six minutes; then wash with water from the tap, and before 

 the glass dries cover the surface with the following stain : 



Fuchsin saturated alcoholic solution . . 6 cc. 



Aniline water (see Ex. 9) . . . . 20 

 Warm, and allow the stain to act for three minutes. 



(5) Now wash the cover-glass with water; dry it in an 

 incubator at 37 C. ; mount it in a drop of xylol, and examine 

 with a ^ in. objective. 



Van Ermengem's Method. 



(1) Prepare the cover-glass films as in (i), (2), and (3) 

 above. 



(2) Place the cover-glass films in the following solution, which 

 must be three or four days old : 



Osmic acid 2 per cent, solution . . . 10 cc. 

 20 per cent, tannin solution ... . 20 ,, 

 Glacial acetic acid . . . . . i drop 



Allow the solution to act for one hour at room temperature, or 



five minutes at 50 to 60 C. 



(3) W T ash first in distilled water, then in absolute alcohol, and 

 finally in distilled water again. 



(4) Dip the cover-glass for thirty seconds in a .5 per cent, 

 solution of silver nitrate ; move it about gently in the liquid. 



(5) Drain off the superfluous liquid, and then dip the cover- 

 glass for thirty seconds in the following solution : 



