648 SOME SPECIAL METHODS 



erythrosin. The tubes stain rose-pink, the starch-grains purple. 

 Mount in 2 per cent, aqueous acetic acid, or dehydrate, clear and 

 mount in balsam. Latex vessels and cells are well brought out 

 by a heavy stain of safranin. 



ZiJP {Arch. Rubbercult. Nederland- Indie, iv, p. 65) uses Sudan 

 III. for staining latex vessels. 



Popovici (C. R. Acad. Sci., Paris, clxxxiii, 1926, p. 143) stains 

 with neutral red, cresyl blue and indophenol blue. 



1285 bis. Sieve-tubes. The coagulable protein materials in sieve- 

 tubes are shown up by fixation in alcohol, but their distribution is 

 generally not properly maintained. A. Fischer {Ber. Deut. hot. 

 Ges., 1885, p. 230) plunges whole plants, or long portions of 

 plants such as branch-tips, into boiling water for two to five 

 minutes and then cuts them up for preservation. This coagulates 

 the contents rapidly and the " Schlauchkopfe," artifacts due to 

 cutting, are not obtained. 



Stain half an hour or longer in dilute aqueous anilin blue solution, 

 rinse in water and dehydrate to 70 per cent, alcohol ; counter- 

 stain with 1 per cent, eosin or erythrosin in 70 per cent, alcohol, 

 dehydrate, clear and mount. The anilin blue is intensified by 

 treatment with mild alkali (ammonium hydroxide or carbonate). 

 It needs no differentiation. If desired, sections can be placed in a 

 stronger solution and afterwards differentiated in glycerin. 

 Callose blue, rest pink. (Russow, Sitzungsher. nat. Ges. Univ. 

 Dorpat., vi, p. 63). 



A saturated aqueous solution of eosin followed by a 1 per cent, 

 solution of methylen blue in 90 per cent, alcohol also gives a 

 good stain. Eosin fifteen to twenty minutes, wash in dilute alcohol, 

 stain in methylen blue one to two minutes, dehydrate rapidly in 

 absolute and clear with clove oil. This is also good for latex, 

 medullary rays, the development of sieve tubes and for con- 

 ducing parenchyma. 



Harrar {Bot. Gaz., Ixxxvi, 1928, p. Ill) recommends Bismark 

 brown and Heidenhain's haematoxylin for the phloem tissues of 

 woody plants. 



1286. Surface features of plants may frequently be studied by 

 reflected light. Neuwirth's Casting Method {Zeits. Zuckerind. 

 Czechoslovak. RepubL, liv, 1930, p. 341). Place plants in an 

 ether-alcohol and acetic acid solution of collodion with addition 

 of castor oil or paint on a film with a brush. The mixture is 

 coloured by a highly concentrated acetic-acid-fuchsin solution. 

 Strip off film as soon as it dries at the edge. The surface details 

 of roots, stems and leaves and numbers of stomata per square 

 millimetre of leaf surface, the latter by means of miniature 

 quadrats and transects, may be studied. Long and Clements 

 {Amer. Journ. Bot., xxi, 1934, p. 7) also use a solution of cellulose 

 acetate. Artsikhovskaia {Journ. Bot, U.S.S.R., xvii, 1932, 



