744 HISTOLOGIC TECHNIC 



Mix the ingredients in the above order, and after twenty-four hours 

 filter. It may be necessary to use a drop or two of ammonia to complete 

 the solution of the carmin. This is again removed by evaporation. 



Tissues are to be overstained in the carmin solution, and differen- 

 tiated in acid alcohol (70 per cent, alcohol containing 0.5 to 1 per cent, 

 of hydrochloric acid) until the red color is no longer removed in clouds. 

 The sections are then well washed with several changes of 95 per cent, 

 alcohol, cleared and mounted. This is a most excellent dye for staining 

 embryos in toto. 



Alum Carmin: 



Potassium alum 5 grm. 



Distilled water (hot) 100 c.c. 



Carmin 1 grm. 



Mix in the order given, boil for twenty minutes, and when cold filter. 

 Picro-Carmin: 



Ammonium hydrate 5 c.c. 



Distilled water 50 c.c. 



Carmin 1 grm. ; when dissolved, add 



Saturated aqueous solution of 



picric acid 50 c.c. 



Expose to light and air for two days; filter. 



Picro-carmin is used as a progressive stain. Since the picric acid is 

 soluble in alcohol, dehydration should be rapid, or a crystal of picric 

 acid should be added to the alchohol used for dehydration. 



Aceto-Carmin. This is an invaluable fluid for certain purposes, 

 especially where it is desired to study nuclear structure, chromosomes 

 and spindles in fresh and uncut (teased) tissue. The tissue is simul- 

 taneously fixed and stained in this mixture, and remains preserved in the 

 fiuid in a condition favorable for study for a considerable time. The 

 stained tissue, e.g., insect testes, etc., is teased out on a slide in the fluid, 

 covered with cover glass, and may then be studied under an oil immer- 

 sion lens. The mitotic figures are almost as clear as in sectioned ma- 

 terial. The solution is made by dissolving to saturation carmin in boil- 

 ing acetic acid of 45 per cent, strength, and filtering. 



Safranin. This dye is a coal-tar derivative; it is an excellent 

 nuclear stain. Like carmin, safranin yields a deep red color. 



Safranin (Griibler's) 1 grm. 



Distilled water . 100 c.c. 



