THE INDUCTION OF LARVAL MOLTS IN DROSOPHILA

¹ Department of Zoology, Columbia University, New York

1. Larval head parts of 1st and 2nd instar larvae without nervous system and ring glands were transplanted into the abdomen of adult male flies, together with two larval ring glands from mature larvae. The transplanted heads molt once or twice, as indicated by the presence of double or triple mouth parts.

2. Head parts transplanted in the same manner, but without larval ring glands fail to molt. This shows that the larval ring gland hormone induces larval molting.

3. Head parts without their nervous system and ring glands were also transplanted into the abdomen of 3rd instar larvae. The transplantations were performed either homo- or heteroplastically. In either case molting was induced. The molting hormone of the ring gland is thus not species-specific.

4. Very young organ anlagen were transplanted together with anterior larval head segments after the removal of the nervous system into adult male hosts. It was found that these organs were able to develop in their new environment in the absence of ring glands. Older organ discs transplanted in the same manner develop however only in the presence of ring glands. These experiments are discussed in relation to hormone level and tissue competence.