WING FORM AND GENE FUNCTION IN NINE GENOTYPES OF DROSOPHILA MELANOGASTER

¹ From the Washington Square College of Arts and Sciences, New York University, and the Marine Biological Laboratory, Woods Hole, Massachusetts

1. Nine genotypes, including a number of new mutants, affecting the wing form and the wing venation were found to vary in phenotype between 16° C. and 32° C.

2. The dominant-recessive relationships of these new mutants and the linkage group in some cases was determined.

3. The limits for the future phenotype of each character are demarked at fertilization by the genotype established. The phenotype of each individual is subsequently developed at a point within these extremes as the resultant of the interacting forces of the genotype and the individual's environment.

4. The nature of the response to temperature (positive or negative) throughout the viable range is a function of the particular allele.

5. All of the genes modifying the wing form were found to be thermolabile during the larval period prior to puparium formation.

6. All of the genes associated with minor modifications in the wing venation had their temperature-effective-period during the pupal stage following puparium formation.

7. The interval of the temperature-effective-period is not a function or characteristic of the allele or the locus but of the stage in development when the action of the gene or its products is thermolabile.

8. The rate of the response and the duration, if not the maximum, are determined by the allele and the environment.

9. The onset and maximum duration of this period are determined by definite developmental stages.

10. Apparently the development of the dorsal mesothoracic disc must progress to a certain point before the wing form loci become effective in further growth and differentiation of this structure and it swing bud. Loci causing minor modifications in the wing venation cannot become operative until much later when the final morphological differentiation of the wing is well advanced.