Provide the experimental verification of the chromosomal theory of inheritance.

(N/A) Sutton and Boveri proposed that the pairing and separation of a pair of chromosomes would lead to the segregation of a pair of factors they carried. Sutton combined the knowledge of chromosomal segregation with Mendelian principles and called it the chromosomal theory of inheritance.
The experimental verification of the chromosomal theory of inheritance was provided by Thomas Hunt Morgan and his colleagues. This work led to the discovery of the basis for variations produced by sexual reproduction. Morgan worked with the tiny fruit flies, $Drosophila \text{ } melanogaster$, which were found to be very suitable for such studies due to the following reasons:
$1$. They could be grown on a simple synthetic medium in the laboratory.
$2$. They complete their life cycle in about two weeks.
$3$. $A$ single mating could produce a large number of progeny flies.
$4$. There is a clear sexual dimorphism, i.e., males are smaller and females are larger.
$5$. They have four pairs of chromosomes which differ in size.
$6$. They exhibit many types of hereditary variations that can be observed under a low-power microscope.