Staining Animal Sections 147 



(3) Wash in distilled water, then in ordinary tap water ; 

 the latter will fix the dye and cause the colour to become 

 blue. 



When a section has been overstained with hematoxylin, 

 the excess of colour may be removed by soaking it for a few 

 minutes in a | per cent, solution of glacial acetic acid in 

 distilled water, then wash again in tap water. 



(4) Dehydrate in methylated spirit. 



(.5) Clear in clove oil, and mount in Canada balsam. 

 Double Staining with Haematoxylin and Eosin. — Stain 

 the section in haematoxylin, as directed above, then place it 

 in an alcoholic solution of eosin — about 1 grain of eosin to 

 an ounce of methylated spirit is strong enough — and let it 

 soak for about five minutes ; wash well in methylated spirit, 

 clear in clove-oil, and mount in Canada balsam. 



Aniline Blue-Black. — Dissolve 30 grains of nigrosine in 

 3|- ounces of distilled water, then add 1 ounce of rectified 

 alcohol and filter. This stain is only used for sections of 

 brain and spinal cord. Immerse the sections for from thirty 

 to sixty minutes, wash in water, dehydrate in methylated 

 spirit, clear in clove-oil, and mount in Canada balsam. 



Aniline Blue. — Make a 1 per cent, solution of soluble 

 aniline blue in distilled water and filter. Stain the section 

 for five to ten minutes, wash in water, and place in methy- 

 lated spirit, in which it must soak until the excess of 

 colour is removed. Clear in clove-oil and mount in Canada 

 balsam. 



This stain is useful for cardiac glands of the stomach, 

 brain and spinal cord. 



Golgi's Nitrate of Silver Methods. — These are chiefly 

 employed for investigating the relations of cells and fibres 

 in the central nervous system. Two methods are mostly 

 used, as follows : 



(a) Very small pieces of the tissue, which have been 

 hardened for some weeks in bichromate solution or Miiller's 

 fluid, are placed for half an hour in the dark in 0'75 per 

 cent, nitrate of silver solution, and are then transferred for 



10—2 



