The Induction of Chromosome Exchange Aberrations by Ionizing Radiations: The ‘Site Concept’

Abstract
Wolff and his collaborators have proposed that there are only four ‘sites’ in the Tradescantia nucleus, each with a radius of ∼0·3 μ, within which 2-break aberrations can be formed by x-rays or by fast neutrons. In Vicia faba there are two sites. This paper shows that this concept is incompatible with data describing the production of 2-break aberrations by alpha-particles in Vicia faba. The arguments advanced in support of the ‘site’ concept are criticised.