708 GENERAL TECHNIQUES FOR CLASSES OF PLANTS 



removes excess stain in 95 per cent, alcohol and counterstains in 

 2 per cent, clove oil solution of light green for one to three minutes. 

 He then washes in absolute alcohol or carbol-turpentine, clears in 

 xylol and mounts in balsam. Parasite tissue stained red, host 

 tissues green. If the tissues do not stain readily mordant with a 

 freshly prepared 1 per cent, aqueous solution of potassium per- 

 manganate, rinse in water and pass up to 85 per cent, alcohol. 

 Chamberlain (Methods, 1932, p. 273) suggests phloxine instead 

 of Magdala red. Diemer and Gerry {Science, liv, 1921, p. 629) 

 suggest that fungal mycelia in woody tissues may be detected by 

 taking advantage of the oxidising and reducing powers of the 

 mycelium. They find that a silver nitrate solution stains the 

 mycelium brown or orange and the wood lighter brown. 



Moore {Science, Ixxvii, 1933, p. 23) recommends the use of 

 pheno-safranin, prepared according to Satory's formula, viz., 

 carbolic acid crystals 20 grm., lactic acid syrup 20 grm., glycerin 

 40 grm., distilled water 20 c.c, pheno-safranin 0-5 grm. or less. 

 Mordant fixed sections with 2 per cent, iron alum for two hours. 

 Stain and then differentiate with 0-5 per cent, iron ahnn in 

 0-5 per cent. HCl, or with alcohol. Intensify stain with 1 per cent, 

 ammonia. The host tissue destains faster than the parasite. 



Cartwright {Ann. Bot. xliii, 1929, p. 412) treats mycelium in 

 wood sections as follows : Stain in 1 per cent, aqueous safranin ; 

 it is usually sufficient to cover the section with stain and drain it 

 off immediately. Wash in water, leaving a slight excess of stain. 

 Cover the section with picro-anihn blue (25 c.c. saturated aqueous 

 anilin blue and 100 c.c. saturated aqueous picric acid) and warm 

 over a flame until the liquid is on the point of simmering. Wash 

 out all the blue with water. Dehydrate, clear in clove oil, wash in 

 xylol and mount in balsam. The mycelium is a clear blue, ligni- 

 fied walls red. Badly decayed wood takes up some blue, but the 

 mycelium is clearly differentiated by its depth of stain. 



Stoughton {Ann. Applied Bot., xvii, 1930, p. 162) stained 

 Bacterium malvacearum, in diseased Gossypium with thionin and 

 orange G. Stain for one hour in thionin solution (0-1 grm. thionin 

 in a 5 per cent, solution of phenol in 100 c.c. of distilled water), 

 dehydrate to absolute and counterstain in a saturated solution of 

 orange G in absolute alcohol, for one minute. Wash thoroughly 

 in absolute alcohol, clear and mount. Parasite, violet-purple ; 

 cellulose walls, yellow or green ; xylem and chromosomes, blue ; 

 spindle, purple. See Margolena {Stain Tech., vii, 1932, p. 25) 

 for a modification. 



See also Blackman, New Phijt., iv, 1905, p. 173 (Congo red for 

 uredinea^); Durand, Phytopath., i, 1911, p. 129; Hubert, 

 Phytopath., xii, 1922, p. 440 ; Hadley, J. Bad., ix, 1924, p. 405 

 (staining lytic areas produced by bacteriophage) ; Ridgeway, 

 Phijtojyath., vii, 1917, p. 389. 



