Experimental verification of the chromosomal theory of inheritance was done by Thomas Hunt Morgan.

Explanation:
The chromosomal theory of inheritance was proposed by Walter Sutton and Theodor Boveri in 1902. It stated that genes are located on chromosomes and that the behavior of chromosomes during meiosis and fertilization accounts for inheritance patterns. However, this theory needed experimental proof.

Thomas Hunt Morgan, an American geneticist, performed experiments on fruit flies (Drosophila melanogaster) in the early 1900s. He observed that the eye color of fruit flies was inherited, and he also observed that eye color was linked to gender. Morgan's experiments provided evidence to support the chromosomal theory of inheritance.

Key experiments conducted by Thomas Hunt Morgan are:

1. Discovery of sex-linked inheritance:
Morgan discovered that the white-eyed mutant trait was inherited only in males and not in females. He concluded that the gene for the white-eyed trait was located on the X chromosome, and that males have only one X chromosome, while females have two.

2. Linkage mapping:
Morgan also discovered that certain traits were inherited together more often than expected by chance. He concluded that these traits were located on the same chromosome and were inherited together because of their physical proximity on the chromosome. This led to the development of the concept of linkage mapping.

3. Crossing over:
Morgan also observed that sometimes the traits that were linked on the same chromosome could be separated by a process called crossing over. This occurs when homologous chromosomes exchange genetic material during meiosis.

Morgan's experiments with fruit flies provided strong evidence to support the chromosomal theory of inheritance, and he was awarded the Nobel Prize in Physiology or Medicine in 1933 for his work.