80 Modern Microscopy. 



flat and the excess of balsam is squeezed out. The slide 

 must now be put aside for a day or two to allow the balsam 

 to harden ; the exuded medium may then be washed away 

 with some benzol and a soft camel's hair brush, then dry 

 the slide carefully with a cloth and apply a ring of cement, 

 The above method answers well for mounting sections 

 quickly, but when time will admit the following is a much 

 better way. Clear the section and place it in turpentine. 

 Clean a cover-glass, and moisten the surface of a slide with 

 your breath ; apply the cover-glass to the slide, and make 

 sure that it adheres. Place a few drops of balsam on the 

 cover, into which put the section. Now put the slide away 

 in a box, or in some place out of reach of dust, for twelve 

 hours, so that the benzol may evaporate from the balsam. 

 Clean a slide, warm it gently over the flame of a spirit- 

 lamp. Apply a drop of balsam to the surface of the 

 hardened balsam on the cover-glass ; take the cover up in 

 a pair of forceps, and bring the drop of fresh balsam in 

 contact with the centre of the warmed slide. Ease the 

 cover down carefully, so that the air-bubbles may escape. 

 Now press on the surface of the cover-glass until the section 

 lies quite flat. Set the slide aside to cool ; the exuded 

 balsam may then be washed away with methylated spirit 

 and a soft rag, and a ring of cement applied. 



LESSON 4. 



STAINING BLOOD AND EPITHELIUM, TEAS- 

 ING OUT TISSUES AND MOUNTING IN 

 AQUEOUS MEDIA. 



Double-staining Nucleated Blood Corpuscles. 



Stain A. Dissolve 5 grains of rosin in J ounce of dis- 

 tilled water, and add J ounce of rectified alcohol. 



Stain B. Dissolve 5 grains of methyl green in an ounce 

 of distilled water. 



Place a drop of frog's blood on a slide, and with the edge 



