LIST OF EE AGENTS, ETC. 385 



Preparation. — Either concentrated glycerine or the dilute 

 solution may be used for mounting. The latter is made 

 by mixing equal parts of glycerine and distilled water. 



18. Hydrochloric or Muriatic Acid. 



Use. — Dissolves crystals of calcium carbonate and of calcium 

 oxalate, the former with the latter without effervescence ; 

 decalcifies ; macerates ; turns lignified cell-walls yellow. 



Preparation. — The concentrated acid, which is perfectly 

 colorless, may be diluted with distilled water to the va- 

 rious strengths needed. Keep in glass-stoppered bottles. 



19. Injection Masses. 



Starch. — The starch injection mass serves well for coarse 

 anatomical work, and is easily managed. The mass it- 

 self consists of one volume of dry starch, one volume of 

 a two and a half per cent, aqueous solution of chloral 

 hydrate, one-fourth volume of ninety-five per cent, alco- 

 hol, and one -fourth volume of the color. The last is 

 prepared by mixing together equal volumes of the dry 

 color — e. g., vermilion or soluble Prussian blue, glyce- 

 rine, and ninety-five per cent, alcohol. These ingredients 

 should be thoroughly ground together in a mortar, and 

 strained through fine muslin to remove the lumps which 

 might clog the cannulae of the syringe. This color mixt- 

 ure may be kept permanently in a closed bottle, and 

 added to the starch mass as desired. 



Oum-arahic. — Make a thick paste by dissolving gum-ara- 

 bic in water to which has been added sufiicient soluble 

 Prussian blue to produce the desired depth of color ; 

 strain the paste through fine muslin ; place the injected 

 specimen in alcohol to harden the paste. 



20. Iodine. 



Use. — Colors starch blue, proteid substances (protoplasm, 

 etc.) brown, cellular cell-walls light-yellow, cuticularized 

 and lignified cell-walls yellow. 



Preparation. — Dissolve to saturation crystals of potassium 



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