296 THE ESSENTIALS OF HISTOLOGY. 



6. 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. 



7. Picro-carminate of ammonia (picro-carmine, Eanvier). To a saturated 

 solution of picric acid add a strong ammoiiiacal solution of carmine, until a 

 precipitate begins to form. Evaporate on the water-bath (or, better, allow 

 it to evaporate spontaneously) to ith ; filter from the sediment and evaporate 

 the filtrate to dryness. Make a 5 per cent, solution of the residue, diluting 

 further as required. 



8. Lithium-carmine. Dissolve 2J grammes of carmine in 100 cubic centi- 

 meters of a saturated solution of lithium carbonate. This solution is 

 valuable for staining pieces of tissue in bulk. They may be left in it for 

 24 hours or more, and should then be placed in acidulated alcohol (see 

 below). Sections may be stained by it in a few minutes. The addition of 

 2 to 3 times its volume of saturated solution of picric acid to the above 

 solution of carmine in lithium carbonate has been recommended as a ready 

 and convenient way of preparing picro-carmine. 



9. Borax-carmine. Dissolve 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 keeping. It is 

 useful for staining in bulk. 



After staining with lithium-carmine or 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. 



10. Magenta. Take 5 cubic centimeters of a 1 per cent, alcoholic solution 

 of magenta, and to it add gradually 20 cubic centimeters glycerine. Dilute 

 with water to 100 cubic centimeters. This solution is for fresh tissues and 

 for sections to be mounted in glycerine. For sections to be mounted in 

 Canada balsam a solution in alcohol is used. 



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

 nuclei. The tissue- elements having been fixed by dilute chromic and acetic 

 acid, or by Flemming's solution, 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 may contain a little free 

 hydrochloric acid) until the colour is washed out from everything except the 

 nuclei ; they are then at once transferred to clove-oil, and from this are 

 mounted in Canada balsam. 



12. Aniline blue-black. Dissolve 1 gramme of aniline blue-black in a mix- 

 ture of 30 parts of water with 20 of alcohol. This is sometimes used for 

 staining sections of the central nervous system. 



13. Marches solution. This is a mixture of Miiller's fluid (2 parts) with 1 

 per cent, osmic acid (1 part). It is of great value for staining nerve-fibres in 

 the earlier stages of degeneration, before sclerosis sets in (especially a few 

 days after the establishment of a lesion). All the degenerated medullated 

 fibres are stained black, whilst the rest of the section remains almost un- 

 stained. It is best to put thin pieces of the brain or cord to be investigated 

 into a large quantity of the solution (after previously hardening for 10 days 



