1. T. H . Morgan worked on fruit flies (Drosphila Melanogaster).
2. They are found suitable for studies in genetics for the following reasons :
- They could be grown on simple synthetic medium in the laboratory.
- The flies complete their life cycle in about two weeks.
3. Morgan carried our many dihybrid crosses in Drosophila, with the genes that were sex-lined, i.e., the genes are present on the X-chromosome.
4. He observed that the two genes under consideration in his experiments, did not segregate independently as in the case of characters studied by Mendel.
