Chromosome squashes in Cereals

Abstract

Root tips were soaked 1–2 hours at 18–20° C. in a freshly prepared saturated aqueous solution of α-bromonaphthalene, 1–2 hours in water, and fixed in a mixture consisting of 1% chromic acid, 5 ml.; 2% osmic acid, 1 ml.; and 0.002 M 8-oxyquinoline, 1 ml. for 0.5–1.0 hour at 10–14°C. They were then successively treated as follows: water 1–2 minutes; 1% H₂SO₄, 10–15 minutes; water, 1–2 minutes; 1% CrO₃, 0.5–1.0 hour; water 3–5 minutes; 1 N HCl, 45 minutes at 60°C; water 3–5 minutes; leucobasic fuchsin (de Tomasi) 0.5–1.0 hour. The brightly stained tips of the roots were cut off and squashed in the usual manner in a drop of aceto-carmine under a cover glass. The cover glass was sealed with paraffin and the slide stored overnight. The paraffin was removed and the cover glass separated in a 1:1 mixture of acetic acid and n-butyl alcohol. Final processing consisted of passing the slide through pure n-butyl alcohol; a 1:1 mixture of redistilled turpentine and n-butyl alcohol (to remove-the osmic acid stain); n-butyl alcohol, 2 changes, and covering in balsam.