GENERAL STAINING 655 



95 per cent, alcohol and absolute and clear in xylol. Lignified 

 tissues blue, cellulose tissues red. 



Aqueous solutions may also be used, but the stains then wash 

 out even more rapidly. 



1306. Mallory's Triple Stain is recommended by Pujiula 

 {Broteria, Ser. Bot., xxv, 1931, p. 51) for Pinus sections. He 

 obtained the best results by fixation in 90 to 95 per cent, alcohol 

 and the substitution of Ziehl's basic fuchsin for the acid fuchsin. 



1307. Polychrome Methylen Blue is a quick and easily controlled 

 stain, differentiating well. Stain and then mordant for a few 

 minutes in 10 per cent, aqueous ammonium molybdatc before 

 dehydrating (Barratt, Ann. Bot., xxx, 1916, p. 92). 



1308. Light Green and Sudan III (Bugnon, C. R. Acad. Sci., 

 Paris, clxviii, 1919, p. 62). Stain in saturated aqueous or alcoholic 

 light green, acidulated with hydrochloric or acetic acid. Wash in 

 water to remove stain from all but the lignified tissues and then 

 stain in an alcoholic solution of Sudan III. Bugnon suggests some 

 triple combinations, involving ammoniacal gentian violet or other 

 stains in addition. 



1309. Staining Cell-walls in Meristematic Tissues. Foster 

 {Stain Tech., ix, 1934, p. 91) describes the use of tannic acid and 

 ferric chloride (cf. Lange, Planta, iii, 1927, p. 181). Transfer from 

 water to 1 per cent, aqueous tannic acid for ten minutes. Add 

 1 per cent, sodium salicylate to the tannic acid as a fungicide. 

 Wash thoroughly in water and place in 3 per cent, aqueous FeClg 

 several minutes. Cell-walls of meristems should appear black or 

 dark blue, and nuclei and cytoplasm grey. Wash, and if too weak, 

 replace in tannic acid solution. Transfer to 50 per cent, alcohol. 

 Stain forty-eight hours in 1 per cent, safranin in 50 per cent, 

 alcohol. Wash in 50 per cent, alcohol and destain in weak acid 

 alcohol. Dehydrate and clear. Northern (Stain Tech., xi, 

 1936, p. 23) gives alternative schedules. 



CYTOLOGICAL STAINS 



1310. Most important are Heidenhain's, Mayer's and Cole's 

 ha^matoxylins, Newton's gentian violet iodine (modified Gram 

 stain) and thionin. Cole's rapid hasmatoxylin method is highly 

 adaptable. 



Stain combinations are best avoided for most work, as they are 

 frequently capricious. But good results can frequently be 

 attained. The following are the more important combinations 

 used. 



1311. Iron Haematoxylin and Safranin. See Lenoir {Rev. 

 Gen. Bot., xxxviii, 1926, p. 354). Mordant sections two to three 

 hours in 3 per cent, ferric alum, wash in water and stain three 

 hours in haematoxylin. Wash in water and differentiate in 



