Drosophila melanogaster has been extensively used to test the chromosome theory of heredity. It was instrumental in the early development of genetics, with Thomas Hunt Morgan and his team at Columbia University using it to provide strong evidence for the theory. This work led to the formulation of the chromosome theory, which states that genes are located on chromosomes and that inheritance patterns can be explained by the behavior of chromosomes during meiosis. 

Drosophila have a short life cycle, allowing for quick observation of multiple generations, crucial for genetic analysis. They produce many offspring, making it easier to observe patterns of inheritance. They can be easily bred and maintained in a laboratory setting. 

Drosophila also possess polytene chromosomes, which are large and visible under a microscope, facilitating the mapping of genes. They readily develop mutations, allowing researchers to study the effects of altered genes.