684 PLANT CHROMOSOMES 



Stain Tech., v, 1930, p. 13). Stain, from water, for five minutes. 

 Wash in running water, or several changes of tap-water, dehydrate, 

 clear and mount. 



Sass's {Stain Tech., iv, 1929, p. 127) Modification of 

 Mayer's Haemalum. Dissolve 50 grm. ammonium alum in 

 1 litre of boiling water. Remove from hot plate and add 1 grm. 

 hsematoxylin and 1 grm. sodium iodate (NalO,), cool and filter. 

 The stain keeps several months, but is best used when fresh. 

 Filter whenever a " metallic " scum appears. Transfer to stain 

 from water, wash in distilled water, then in tap-water (or 0-001 

 per cent, sodium carbonate), and again in distilled water ; dehy- 

 drate, clear and mount. The stain is primarily an histological one. 

 By adding to the stain alum to saturation and 2 to 5 per cent, of 

 acetic acid, nuclear selectivity is increased. Chromosomes of 

 Lilium ovary in meiosis are stained in one hour and require no 

 differentiation. 



1367. Feulgen's Nucleal-farbung may be used. See Fuelgen 

 {Handbuch Biol. Arheitsmeth., ccxiii, 1926, -p. 1055), for detailed 

 discussion of methods. 



GuRNEY {Australian J. Exp. Biol, and Med. Sci., xi, 1933, 

 p. 157) obtains brilliant staining of wheat anthers cut at 10 /n. 

 Fix in Carnoy, in saturated mercuric chloride (HgClg) in 2 per 

 cent, acetic acid or in a mixture of equal parts of chromic acid and 

 formalin. Fix sections to the slide and hydro lyse with N hydro- 

 chloric acid for ten minutes at 60° C. Cool the acid by immersing 

 the vessel in running water and then transfer the slides to cold 

 acid ; this prevents sections floating off the slide. Stain for two 

 hours ; all chromatic material takes a deep purple colour seen 

 only in daylight. Use a Wratten green B filter with artificial 

 light. 



Fuelgen's method can be applied to unfixed pollen mother-cell 

 smears ; the N hydrochloric acid solution then appears to serve 

 as a coagulator of the cell contents. 



1368. Safranin. Though red stains are usually best avoided, 

 the following method gives useful results. Tuan {Stain Tech., v, 

 1930, p. 103) stains sections and smears in safranin and dehydrates 

 in a series of alcohol solutions containing 1-5 per cent, picric acid 

 and constantly decreasing percentages of water. Differentiation 

 is chiefly effected in 83 per cent, alcohol containing 1-5 per cent, 

 picric acid and completed in the final dehydrating and clearing. 

 Counterstain in clove oil if desired. 



See also Geitler, Ziichter, i, 1929, p. 243. 



Thaler {Mikrokosmos (Stuttgart), xx, 1927, p. 203) describes 

 the technique for the following nuclear stains : gallamin blue, 

 coelest blue, gallocyanin, coerulein A and gallein. 



Stain combinations are rarely used in modern chromosome 

 studies. For some possible methods see Cytological Stains. 



