COCHINEAL AND CARMINE 503 



STAINING IN BULK. 



Embryos which are to be mounted whole or cut into serial sections 

 are commonly stained before they are imbedded. The time given for 

 the action of the following stains is that required in the preparation of 

 i2-mm. pigs. Larger or smaller objects should, of course, receive a 

 longer or shorter treatment. 



Alum cochineal. 



Cochineal 60 gm. 



Potassium alum 60 gm. 



Water 800 c.c. 



Boil vigorously for 20 minutes. Cool and filter. Boil the filter 

 paper and contents with more water for the same length of time. Cool 

 and filter. Repeat the boiling and filtering until the powder disappears 

 from the residue. Then put all of the filtrate together, boil for about 

 20 minutes and make the volume up to 800 c.c. 



Stain 1 2 -mm. pigs for about 36 hours. Wash in water for 10 to 15 

 minutes; 50 per cent, alcohol, 20 to 30 minutes; 70 per cent., i hour; 80 

 per cent. Imbed in paraffin and cut in serial sections. 



Counterstaining the sections in the solution of Orange G described 

 with Heidenhain's iron hasmatoxylin will bring out the nerves beautifully. 

 The paraffin is removed in xylol, the sections passed through absolute 

 and xylol, absolute, and 95 per cent, to the stain. Wash in several changes 

 of 95 per cent.; and pass back through absolute, and absolute and xylol, 

 to xylol. 



Borax carmine. 



Borax 20 gm. 



Carmine 30 gm. 



Water 500 c.c. 



Boil until everything is dissolved. Cool and add 500 c.c. of 70 per 

 cent, alcohol. Let stand 24 hours and filter. 



Stain a i2-mm. pig about 36 hours; water 10 to 15 minutes; 0.5 per 

 cent, hydrochloric acid in 70 per cent., 30 minutes to i hour; 70 per cent, 

 changed several times, i hour; 80 per cent, changed twice. Imbed in 

 paraffin and cut in serial sections. The sections may be counterstained 

 as directed under alum cochineal. 



SELECTIVE STAINS. 

 Mallory's Phosphotungstic Acid Haematoxylin. 



Haematoxylin o. i gm. 



Water 80.0 c.c. 



10 per cent. aq. sol. of phosphotungstic acid (Merck) 20.0 c.c. 



Dissolve the haematoxylin in a little water with the aid of heat; cool, 

 and add to the rest of the solution. If the solution does not stain, it may 



