FLAG ELLA STAINING 63 



and heat as before, allowing to steam for from one to two minutes. Wash well 

 in distilled water, dry and examine. A pair of Comet's special forceps for 

 slides will be found convenient in the above manipulations. 



Fig. 10. — Cornet's forceps for glass slides. 



(2) Van Ermengem's method. 



Three solutions are required in this method : — 



A. Fixing solution. 



Osmic acid, 2 per cent, solution . . . .1 part. 



Tannin, 20 per cent, solution . . . .2 parts. 



To each 100 c.c. of this mixture add four to five drops of glacial acetic acid. 



B. Sensitising Solution. 



Nitrate of silver .... 0-5 aqueous solution. 



This solution should be kept in the dark and filtered before use. 



C. Reducing Solution. 



Gallic acid ...... 5 grammes. 



Tannin . . . . . . • Z ■>■, 



Fused acetate of soda (or potassium) . . . 10 „ 



Distilled water ...... 350 „ 



{a) Cover the film with solution "A" and allow to act for five minutes at 

 37"" C, or one hour at room temperature. Or heat gently imtil steam rises, and 

 allow the staining fluid to act for fifteen minutes. 



{b) Wash well with distilled water, then in absolute alcohol, and then again 

 in distilled water. 



{c) Treat with solution " B " and allow it to act for thirty seconds, keeping 

 the fluid in movement on the slide. 



{d) Allow the fluid to run off the slide, and without washing treat with " C " 

 for thirty seconds in the same manner. 



{e) Allow fluid to run off and again treat with sensitising solution till the 

 preparation begins to turn black. 



(/) Wash in distilled water, mount in water, and examine under the 

 microscope. 



(3) M^Crorie's method. 



A combined mordant stain is made by dissolving i gramme of tannic acid, 

 and I gramme of potash alum in 40 c.c. of distilled water, and adding to this, 

 0-5 gramme of " night-blue " dissolved in 20 c.c. of absolute alcohol. Filter the 

 stain at least twice before use. Stain with the solution for about ten minutes, 

 changing the stain two or three times during the operation. Then wash gently 



