86 METHODS OP MICROSCOPICAL RESEARCH. 



Cochineal Staining Fluid. 



ALCOHOLIC COCHINEAL. (Mayer's Formula.) 

 Macerate cochineal powder in 70 per cent, alcohol 

 for some days, in the proportion of 10 c.c. alcohol 

 to 1 gramme of the cochineal. 

 Stir frequently and filter. 



Saturate the specimens before staining them with 

 70 per cent, alcohol, and use alcohol of that strength 

 for all the processes connected with the use of this 

 stain, and for diluting it. After staining the speci- 

 mens, wash them in repeated changes of the alcohol 

 until they cease to tint it. 



ALUM COCHINEAL. (Czoker's Formula.) 



Pulverise in a mortar, cochineal 7 grammes, and 

 dried alum 7 grammes; add 700 c.c. of distilled 

 water, and boil down to 400 c.c. When cool add 

 1 per cent, of carbolic acid crystals ; filter several 

 times. It will remain fit for use for about six 

 months, when it must again be filtered, and a small 

 additional quantity of carbolic acid added to it. 



Use it full strength, it does not over stain how- 

 ever long the specimens are left in it. 



The specimens must be immersed in it for at least 

 two hours, and may require to remain immersed 

 from three to six hours. 



It acts as a double stain, colouring the nuclei 

 violet and the tissues red. 



ANILIN BLUE BLACK. 



Dissolve 1 decigramme in 4 c.c. of distilled water, 

 to this add 100 c.c. of rectified alcohol, and keep 

 the solution in a well- stoppered bottle. 



