LABORATORY DIRECTIONS. 475 



is better to transfer the pieces to some standard salt 

 solution and then wash and dehydrate. 



Potassium Bichromate and Formalin. 



Potassium bichromate 2 per 



cent, aqueous solution 90 parts. 



Formalin 10 parts. 



Fix for several days or weeks. Wash in running 

 water and dehydrate with alcohol. This is a good 

 fixation for the central nervous system. 



STANDARD STAINS. 

 Aqueous Borax-carmin Solution. 



Borax 8 gm. 



Carmin 2 gm. 



Water 150 c.c. 



Grind together the borax and carmin. Add the 

 water and in twenty-four hours filter. Stain sections 

 for twelve hours or longer. Treat with acid-alcohol 

 as necessary. 



Alcohol Borax-carmin Solution. 



Carmin 3 gm. 



Borax 4 gm. 



Water 93 c.c. 



Alcohol, 70 per cent 100 c.c. 



Filter and stain as for the aqueous solution. 

 Cochineal Solution. 



Cochineal, powdered 7 gm. 



Alum, roasted 7 gm. 



Water 100 c.c. 



Boil down to one-half its volume, stirring freely. 

 When cool filter and add a few drops of carbolic acid. 

 This fluid does not overstain and acts rapidly. After 

 staining wash in distilled water, as alcohol precipi- 

 tates the alum. 



