244 THE ESSENTIALS OF HISTOLOGY 



solution of alum in water, add 4 cubic centimeters of saturated solution of 

 haematoxylin in alcohol. Let the mixture stand 8 days, then decant, and 

 add 25 cubic centimeters of glycerine, and 25 cubic centimeters of methylic 

 alcohol. 



3. Kleinenberg's Ticematoxylin. This serves better for staining in bulk. 

 Saturate 70 per cent, alcohol first with calcium chloride and then with alum, 

 and after filtration add six to eight volumes of 70 per cent, alcohol. 



Take a freshly prepared saturated solution of haematoxylin in absolute 

 alcohol, and add it drop by drop to the above mixture until it is of a distinct 

 purplish colour. 



This solution improves on keeping. It may if necessary be diluted with 

 more of the mixture. 



When haematoxylin solutions become red instead of blue, a trace of 

 ammonia will restore the requisite colour. 



4. Carminate of ammonia. Prepared by dissolving carmine in ammonia 

 and allowing the excess of ammonia to escape by slow evaporation. The 

 salt should be allowed to dry and be dissolved in water as required. 



5. Picro-carminate of ammonia (picro-carmine). To a saturated solution 

 of picric acid add a strong ammoniacal solution of carmine, until a precipitate 

 begins to form. Evaporate on the water-bath to llh ; filter from the sedi- 

 ment and evaporate the filtrate to dryness. Make a 5 per cent, solution ol 

 the residue, diluting further as required. 



6. Borax-carmine. a. Jthssolve 4 grammes borax and 3 grammes 

 carmine in 100 cubic centimeters of warm water. Add 100 cubic centimeters 

 of 70 per cent, alcohol, filter and let stand. This solution improves on keep- 

 ing. It is useful for staining in bulk. 



/3. Boil 0-5 gramme carmine and 1 gramme borax in 100 cubic centi- 

 meters water. Filter and add acetic acid drop by drop until the original 

 violet colour becomes crimson ; then filter once more. This solution is used 

 for staining sections. 



After staining with borax-carmine, the tissue should in all cases be placed 

 in 70 per cent, alcohol containing 5 drops of hydrochloric acid to 100 cubic 

 centimeters. 



7. Magenta. This may be kept in solution in alcohol (0'5 to 1 per cent.) 

 For fresh tissues and for sections to be mounted in glycerine, an excellent 

 staining fluid is obtained by adding one or two drops to a watch-glass of water. 

 For sections to be mounted in Canada balsam a solution in oil of cloves is 

 used. This is best made by adding a drop of the alcoholic solution to a little 

 oil of cloves in a watch-glass : the sections after being stained are washed 

 in spirit of turpentine. 



8. Gentian violet. Mix 20 cubic centimeters water with 10 cubic centi- 

 meters alcohol and 10 cubic centimeters glycerine, and add to the mixture 

 10 drops of a 1 per cent, solution of gentian violet in alcohol and 10 drops 

 of a 25 per cent, solution of formic acid in water. 



This solution gives excellent results with fresh tissues, especially with 

 epithelium. 



9. Safranin. A saturated alcoholic solution is used for staining cell- 

 nuclei. The tissue elements having been fixed by dilute chromic acid or by 

 alcohol, small shreds or thin sections are placed for 12 to 24 hours in a little 

 of the solution, mixed with half its bulk of water. The shreds are rinsed in 

 absolute alcohol (which must contain no trace of free acid) until the colour is 



