Chromosomes of Sequoia sempervirens; 8-Hydroxy-Quinoline-Castor Oil Pretreatment for Improving Preparation

Living root tips of coast redwood were pretreated for 6 hr at 10-14 C in a homogenized mixture of 0.003 M aqueous solution of about 5 ml of 8-hydroxyquinoline and a drop of castor oil. They were rinsed 2-3 times in Carnoy's alcohol-chloroform-acetic acid (3:2:1), and fixation allowed to continue in this fluid for 1 hr at 60 C. They were then hydrolysed in 1 N HC1 at 60 C for 45 min; washed with distilled water, and squashed in a drop of aceto-carmine or aceto-orcein to make a temporary slide, subsequently made permanent by a quick-freezing method. Our work to date seems to confirm 2n = 66 for S. sempervirens.