Colchicine-Feulgen Leaf Smears

Abstract

The colchicine-Feulgen leaf smear prevents spindle formation, allows the chromosomes to be widely spread in the cell, straightens the chromatids, allows the constrictions to become very noticeable, increases the no. of chromosome plates by preventing anaphase, facilitates smearing, and stains only the chromosomes. Young leaves are generally easily obtainable; roots of the proper sort are to be had only under very special conditions. Mitoses are frequently more numerous in young leaves than in roots. The schedule for specimens of Phlox involves a 1-to 2-hr, pretreatment of young leaves in a 0.2% colchicine soln., fixation in Semmen''s Carnoy (3 vol. absolute alcohol, 1 vol. glacial acetic, 1 vol. chloroform), hydrolysis for 25 min. in 10% HC1 at 58[degree]C, staining in decolorized fuchsin, smearing in 45% acetic acid, and running the material on slide and cover glass through acetic alcohols (1:1, 1:3, 1:9), absolute alcohol, xylol to balsam.