Effects of carbon tetrachloride on mitosis

Abstract

We have observed that carbon tetrachloride produces striking effects on Allium cepa, Allium sativum and Zaphranthus sp. root tips. Root tips were treated for five minutes to a half-hour in carbon tetrachloride and later transferred to normal nutrient medium and fixed at various intervals from half an hour to six hours. Among the prominent changes taking place in the resting nucleus is a dissolution of the nuclear membrane and an outflow of its contents. Similar observations have been made in root tips of Allium cepa treated with chloroform and potassium cyanide. It would appear that the lipoid layer of the nuclear membrane is either dissolved or rendered weak by the chemicals, in consequence of which the nuclear contents flow out. After treatment for 15 min. with carbon tetrachloride, resting and premitotic nuclei break up. A number of chemicals are known to produce this effect, for example, urethane and nitrogen mustard. Perhaps the most characteristic changes brought about by carbon tetrachloride are dissolution of chromatin in the resting nucleus and disorganization of the chromosome arms in the premitotic stages, resulting in their progressively negative reaction to the Feulgen reagent.