Abstract
In Drosophila melanogaster mutant alleles of the segmentation gene wingless fall into two classes: winglessLethal mutations are embryonic lethals with a segment-polarity phenotype; the wingless1 mutation is viable when homozygous and produces a homeotic transformation in adults. This paper further describes the embryonic lethal phenotype, and also pole-cell transplants, experiments with a temperature-sensitive mutation, and clonal analysis with a winglessLethal mutation. It is argued that the wg gene is zygotically required after gastrulation for the normal patterning of each embryonic segment. The gene is still required in the larval stages, and the cell nonautonomy of this function supports the view that the wg gene product may be involved in intercellular signaling during development.
