SOME SPECIAL METHODS 639 



gently with 50 per cent, nitric acid, adding crystals of potassium 

 chlorate frequently (Schultze's reagent) ; this should be done in 

 a fume cupboard, well away from microscopes. 



Cease the treatment with the macerating agent when the ends 

 of the pieces begin to fray. Wash well in several changes of water 

 and complete the separation by teasing. 



Brown {Bull. Torrey. Bot. Club., xlvi, 1919, p. 127) in using 

 Schultze's method, takes equal volumes of acid and water, for 

 safety. Vodrazka {Zeit. zviss. Mik., xliii, 1926, p. 178) treats 

 the material with a specially prepared Schultze's reagent, fol- 

 lowed by ammonium hydroxide, or caustic potash or soda. No 

 boiling is necessary ; thereby the difficulties of the usual Schviltze's 

 reagent are overcome. 



Hydrogen peroxide. Use a 30 per cent, solution, and render it 

 weakly alkaline by the addition of a little sodium or lithium 

 carbonate (Kisser, Cytologia, ii, 1930, p. 56). It attacks the 

 middle lamella first and the lignin later ; finally, after a con- 

 siderable time, cellulose is attacked. It is useful in isolating 

 parenchymatous tissue. 



Eau de JaA'clle is useful in macerating parenchyma, wood or 

 cork and in isolation of cuticle. It should be fresh, and after- 

 wards the material should be treated with dilute 5 per cent, 

 hydrochloric acid. It attacks lignin first and later the middle 

 lamella ; after a considerable time cellulose is attacked. 



Harlow {Bot. Gaz., Ixxxv, 1928, p. 226) uses chlorination 

 followed by hot sodium sulphite solution which removes the 

 middle lamella and dissolves out the lignin. It is suitable for 

 showing the detail of sieve tubes and vessels. 



Aldaba {Amer. J. Bot., xiv, 1927, p. 16) macerates very long 

 fibres of Bcehmeria (up to 550 mm.) as follows : Insert the whole 

 stem in a long glass tube, to the lower end of which is attached a 

 flask, and fill the apparatus up with 5 per cent. KOH. Place the 

 base of the flask on a water bath to heat and circulate the liquid. 

 Isolate the fibres in a large shallow dish and float them on to 

 strips of window glass coated with adhesive. 



1265. Staining Macerated Wood and Fibres. Boil in safranin or 

 other strong anilin dye, wash and dehydrate rapidly in 95 per 

 cent, and absolute alcohol and clear in xylol, allowing the material 

 to settle before decanting the liquids. Loss of stain is reduced by 

 adding a little xylol to the second and subsequent alcohols. 

 Material cleared without staining can be stained by adding a few 

 drops of clove oil solution of dye to the xylol. 



See also Anderson, Am. J. Bot.. xiv. 1927, p. 187 ; Lee, 

 Bot. Gaz., Ixii, 1918, p. 318 ; Tobler-Wolff, Zeit. wiss. Mik., 

 xxxii, 1916. p. 129. 



1266. Bleaching may be carried out l)y the following reagents : 

 hydrogen peroxide (1 part to 4 parts water or 80 per cent, alcohol) ; 



