An Analysis of X-Ray Induced Single Breaks in Neuroblast Chromosomes of the Grasshopper (Chortophaga Viridifasciata)

Abstract

The single chromosomal break is considered the result of a single event[long dash]a single ionization or excitation[long dash]which occurs at random. This hypothesis is supported by (1) the linear proportionality existing between dosage measured in r-units and number of chromosomal breaks, (2) the apparent absence of any threshold below which breaks do not occur. (3) the close correspondence between the observed and expected distribution of the breaks among different cells after each of the doses. The analysis of single breaks in terms of ion pairs per chromosome indicates that only a small proportion of the ionizations produced by x-rays is effective in the production of breaks.