CABMINE AND COCHINEAL 149 



elements of the same preparation. Glands or their secretion often 

 stain grey -green. 



Acids lighten the stain and make it ycllo wish-red. Caustic 

 alkalies turn it to a deep purple. 



All acids must be carefully washed out from the objects before 

 staining, or a diffuse stain will result. The stain is permanent 

 in oil of cloves and balsam. 



Very penetrating and especially useful for Arthropoda. 



It has over the later fluid (next §) the advantage of being more 

 highly alcoholic ; and it does not contain free acid, so that it 

 can he used with calcareous structures which it is wished to pre- 

 serve — which the later fluid cannot. For specimens of Pluteus, 

 for instance, Lee found it excellent. But it only gives good 

 results with such objects as contain the necessary salts, § 248. 



276. Mayer's Alcoholic Cochineal, Later Formula {Mitth. Zool. Stat. 

 Neapel, x, 1892, p. 498). Cochineal, 5 grm. ; chloride of calcium, 

 5 grm. ; chloride of aluminium, 0-5 grm. ; nitric acid of 1-20 sp. gr., 

 8 drops ; 50 per cent, alcohol, 100 c.c. Powder the cochineal and rub 

 up with the salts, add the alcohol and acid, heat to boiling-point, leave 

 to cool, leave for some days standing with frequent agitation, filter. 



Use as the old tincture, the objects being prepared and washed out 

 with 50 per cent, alcohol. Mayer only recommends it as a succedaneum 

 of paracarmine. 



Since this fluid contains in itself all the necessary salts (§ 248), it gives 

 good results with all classes of objects. 



