Staining Animal Seotions 149 



tine ; 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, fqr 

 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 no air-bubbles may be enclosed, 

 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. 



Staining in Bulk. — Place small pieces of the tissue in 

 Grenacher's alcoholic carmine for from one to three days, 

 then transfer to a ^ per cent, solution of hydrochloric acid 

 in methylated spirit for from one to twelve hours, according 

 to the size of the tissue. Wash well in spirit, and soak for 

 a day in 90 per cent, spirit. 



The specimen may then be infiltrated and embedded in 

 paraffin, celloidin or gelatine, but be careful to follow the 

 instructions previously given with each method. 



Flemming's Method for Staining Karyokinetic 

 Nuclei. — Fix the tissue in the following Flemming's 

 solution : 



Osmic acid, 1 per cent, solution ... 80 c.c. 



Chromic acid, 10 per cent, solution ... 15 c.c. 



Glacial acetic acid ... ... ... 10 c.c. 



Distilled water 95 c.c. 



The fixing process is usually complete in twelve hours ; 

 then wash the tissue thoroughly in water and harden in 

 alcohol of gradually increasing strength. Now place small 

 shreds or thin sections in a saturated alcoholic solution of 



