Calvin Bridges pointing to Drosophila map pillar, a method of identification he devised. Each side of the pillar represented one Drosophila chromosome, around 1935.
Calvin Bridges was a student of Thomas Hunt Morgan. Bridges advanced the theory of chromosomal non-disjunction, and did a lot of work on chromosomal banding patterns.
New York high school students set out to find Thomas Hunt Morgan's "Fly Room" at Columbia University, where seminal genetics research took place in the early 20th century.