Genetic Behavior of Euchromatic Segments Inserted into Heterochromatin.

NE type of viable chromosomal rearrangement frequently induced 0 by X-ray treatment is a translocation in which a piece of a chromosome is taken from its normal position and inserted into some other part of the chromosomal complex. When such a rearrangement is intrachromosoma1 the name “transposition” is applied and when it involves two chromosomes it is called an insertional translocation. A number of transpositions and insertional translocations have been described. In this paper results will be given of studies made of five such cases in which euchromatic segments of the X chromosome of Drosophila melanogaster are inserted into heterochromatic regions. Below is a list of X chromosome genes mentioned in this paper with their location on the linkage map given in parentheses (BRIDGES 1938b) : bi, bifid (6.9); cm, carmine (18.9); ct, cut (20.0); 0, crossveinless (13.7); cx, curlex (13.6); dm, diminutive (4.6); dx, deltex (17.0); ec, echinus fa, facet (3.0); g, garnet (44.4); N , Notch, deficiency for f a (3.0); peb, pebbled (7.3+) pn prune (0.8); rb, ruby (7.5); rg, rugose ( I I . ~ ) , rst, roughest (1.7), T U X ) roughex IS.^), SC, scute (o.o+) ) scp, scooped (18.5 5 ) , shf, shifted (17.9), sn, singed (21.0), vs, vesiculated (16.3), w, white (1 .5) , y, yellow (0.0).