Induction of a special Balbiani ring by position effect in the salivary gland chromosomes ofAcricotopus lucidus

Summary Chromosome mutations were induced by X-ray treatment of males ofAcricotopus lucicus. One of the larvae of the F₁-generation showed a dislocation of a segment of the centromeric region into an euchromatic part of the same chromosome as a consequence of mutation. In the new position, in some salivary gland cells, this segment expressed a distinct Balbiani ring. In other cells this Balbiani ring regressed, probably through the influence of ecdysone.