[Investigations on the development of complete and divided imaginal wing discs by implantation in larvae ofEphestia kühniella Z].

1. After implantation of an imaginal wing disc a mirror-image duplication of the disc is formed, starting with the development of a fold at the back edge of the basic region of the implanted wing disc. 2. After implantation of an imaginal wing disc the host's pupation is delayed, the duration of the delay diminishing with the age of the regenerate. 3. Implanted parts of wing discs also duplicate. In this case, too, the duplication starts with the formation of a fold in the basal region. 4. No regenerate is formed, if the implant comprises no material from the basic region. Missing distal parts are not replaced during the host's phase of growth; they are, however, replaced during the phase of the prepupa. 5. If the implant contains material from the basic region, a regenerate always develops. If the basic region is complete, a whole wing disc is regenerated; if it is not complete, only a duplicate of the implant is formed. 6. Not before the 4th day is the regeneration fold finally determined. 7. The regenerate of the implant always consists of fewer cells than a regenerate of the same age in the host. 8. Implanted duplications do not lead to regeneration. On division of such a duplication along its axis of symmetry two new mirror-image duplications are formed (Verklonung). 9. Implanted wing discs which have been incised down into the basic region can give rise to a treble formation besides a normal regenerate. Transplanted treble formations do not duplicate; they only form a normal regenerate. 10. The transplantation of the upper layer of cells leads to the formation of two complete imaginal wing discs. A transplant from the lower layer of cells only duplicates itself. 11. The formation of lacunae is limited to the upper layer of cells. 12. Metamorphosed mirror-image duplications are not inverted. The regions which produce the articular portions are determined by implanted parts of wing discs.