STUDIES IN DIFFERENTIAL REACTIVITY: I. THE RATE AND DEGREE OF DIFFERENTIATION IN THE SOMATIC CHROMOSOMES OF TRILLIUM ERECTUM L.

Abstract

By suitable treatment the somatic chromosomes of a number of plants may be shown to be longitudinally differentiated as to size and staining capacity. Certain well defined regions appear at metaphase and anaphase to be either understained or of reduced diameter or both.Exposure to cold has been found to produce these regions in two varieties of rye and three species of Trillium.The positions of these differential segments have been found to be highly specific for different chromosomes and species.During a 96-hr. period of exposure to cold the number of chromosomes affected and of differential segments per chromosome increases in T. erectum L.After cessation of treatment the chromosomes resume their normal appearance within a few hours.Homologous chromosome pairs often differ in number, size, and position of affected regions. On the basis of data presented in this paper, these differences cannot be taken as conclusive evidence that these pairs are genetically different.