PLANT CHROMOSOMES 687 



alcohol, equal parts absolute alcohol and xylol and finally into 

 xylol. Rcconibine coverslip and slide in xylol balsam directly 

 from the xylol. 



Buck {Science, Ixxxi, 1935, p. 75) makes aceto-carminc jirepara- 

 tions permanent by placing the slides face down for five to thirty 

 minutes in a mixture of equal parts xylol, absolute alcohol and 

 glacial acetic acid. Remove coverslip and rinse in the same 

 solution for five minutes ; drain and wipe clean. Pass through 

 two changes of xylol, absolute alcohol (1 : 1), five to ten minutes 

 each and then xylol ten to fifteen minutes. 



Metz and Gay soak off the cover in equal parts of 95 per cent, 

 alcohol, clove oil and glacial acetic acid ; wash in two changes of 

 95 per cent, alcohol, up to half an hour ; absolute alcohol, five 

 minutes ; clove oil, ten minutes ; xylol, five minutes, 



Steere {Stain Tech., vi, 1931, p. 107) has described a rapid 

 method in which anthers from a selected bud are smeared and 

 fixed and stained by immediate immersion, face downward 

 {cf. Smear Technique) in a Petri dish of hot (steaming) aceto- 

 carmine for 1 to ten minutes. Then rapidly transfer them 

 successively through the following mixtures : 2 parts of 99 per 

 cent, (glacial) acetic acid with 1 part of absolute alcohol, 1 part 

 acetic acid with 2 parts alcohol and 1 part acetic acid with 9 parts 

 of absolute alcohol into absolute alcohol, where the slides are 

 dehydrated for one to two minutes. Clear two to three minutes 

 in equal parts of xylol and absolute alcohol, then xylol and mount 

 in balsam. The whole process requires five to fifteen minutes 

 and the slides are suitable for chromosome counts, etc. 

 See also Sax, Stain Tech., vi, 1931, p. 117. 



1371. Heitz's Koch Methode {Zeits. Bot., xviii, 1926, p. 625) is 

 a method for rapid counting of chromosomes. Fix anthers or 

 ovaries in hot Carnoy (Farmer's formula : 1 part of acetic acid 

 to 2 parts of absolute alcohol) followed by aceto-carmine (45 per 

 cent, acetic acid boiled with carmine, cooled and filtered). Subse- 

 quently the material is teased apart with needles and left some 

 hours for the stain contrast between chromosomes and cytoplasm 

 to intensify. Slides may be dehydrated or dried after staining 

 and mounted in balsam. 



SiNOTo {Cytologia, i, 1929, p. 109) fixes anthers and root-tips in 

 aceto-alcohol (1 part acetic acid to 2 or 3 parts absolute alcohol) 

 and heats them in a tube till the solution begins to boil. The 

 fluid is poured off and replaced with Schneider's aceto-carmine 

 and boiled again. Portions of material are mounted on a slide and 

 covered and squeezed with a pincett to crush the tissues. When 

 overstained the material is destained in 45 per cent, acetic acid 

 to the desired degree. 



De Meijere {Zeits. wiss. Mik., xlvi, 1929, p. 189) treats 

 pollen mother-cells after Heitz's method with Carnoy, places 



