The Effects of Coal Tar and Other Chemicals on the Roots of Allium Cepa

Abstract

In recent years the effects of various chemicals on animal and plant tissues have received considerable attention, in view of the role of tar and certain hydrocarbons in the production of malignant growths. The mechanism of tumor formation is unknown, although the causative agents of some types of overgrowth are well recognized. The study of the effect of carcinogenic agents on the root tip of the onion is especially desirable, since the species is well known cytologically and has been considered by animal and plant cytologists as the standard material for the study of the physiology of the cell. The gross effects of some carcinogenic agents such as coal tar, dibenzanthracene, and Scharlach R on plants have been reported (Levine, 8). The present report deals with the effects of the same chemicals on the root tips of Allium cepa , the common onion. The earlier literature is well known and has been reviewed a number of times. Here only a brief resume will be given of the work that has developed in connection with the study of coal tar and other chemicals, which, some writers believe, are carcinogenic on roots.