“…It is also apparent that movement of the formerly distal C U -W ~ region near the remaining 10% of the proximal heterochromatin yields, instead of an increase, a pronounced decrease in this region. It may be necessary to invoke an additional effect of radiation (perhaps on coiling and consequently pairing, as proposed by YOST and BENNEYAN 1957) to account for the tendency of the hypothesized lesions in proximal euchromatin to be converted to crossovers instead of merely being repaired. (BATEMAN and CHANDLEY (1965) have suggested, on the basis of dose-response studies, that there are opposing forces operating in this region.)…”