476 APPENDIX III. 



Acetic acid, Glacial. Used as reagent for fat oils, 34. 



1 per cent. For fixing the nucleus, espepially in combination 

 with methyl-green or gentiana-violet (q.v.\ and as an addition to the 

 mountant in mounting carmine preps., 250. 



2 per cent. For fixing and defining nuclei, 404. 



Acetic acid is an excellent clearing reagent for rendering tissues trans- 

 parent, and showing up the cell-walls, 210, 216, 270. It is like- 

 wise used to distinguish crystals of oxalate of lime as they are not 

 soluble in it, 63. In very dilute solution (0-5 per cent.) it is useful 

 for somewhat decolorising overstained preps., 272, 274. 

 and Gentiana-violet. See Gentiana-violet. 

 and Methyl-green. See Methyl-green. 



Agar-Agar. Obtained from Eucheuma gelatines, or Gigartina speciosa, is 

 used in the East in the place of ordinary gelatine for preparing 

 soups and jellies. It bears, without liquefying, higher temperatures 

 than ordinary gelatine. It is a culture material for bacteria, 283 ; 

 and in ^ per cent, solution brings on conjugation in Spirogyra, 292. 

 Alcohol, Absolute. Where the alcohol should contain a very specific pro- 

 portion of water, it is better to use absolute alcohol diluted, as 

 ordinary spirit varies slightly in strength, and almost always con- 

 tains acids. Thus, material preserved for working with carbonate 

 of lime crystals (cystoliths) always shows these dissolved if kept in 

 ordinary spirit. Where expense is an object, methylated spirit 

 only about one-tenth the price can however for most purposes be 

 used. 



50 per cent. Used with alkanet for resin reaction, etc. See 144 ; 

 also for making picric alcohol, and picric aniline-blue, and magenta 

 solution (q.v.). 



82 per cenk Used to harden celloidin in. See 400. 

 Acidulated. 70 per cent, alcohol + 0'5 per cent, hydrochloric acid. 

 Used in overstaining. See 273. 



and Glycerine, half and half. Used for softening hard tissues pre- 

 served in alcohol, and thus preparing them for sectionising. From 

 twenty -four to forty-eight hours suffices. 

 Methylated. See above under Absolute Alcohol. 

 Picric. Picric acid dissolved in 50 per cent, alcohol. An exceedingly 

 good fixing and staining reagent for filamentous algae. Needs care- 

 ful washing out if staining with logwood is desired. See p. 248. 

 Alkanet root and alcanna tincture. Used for resin reactions. The alcoholic- 

 tincture of alcanna is added to so much water that the resin will not 

 dissolve in it, or a thin chip of Alkanet root, washed in water to 

 remove dust, can be placed with the preparation, and 50 per cent, 

 alcohol run under the cover-glass. The resin drops may take so 

 long as an hour to colour deep red, 144. The coloured drops are 



