Classical Genetics (Chapters 14 and 15)

Classical genetics is based on the work of Gregor Mendel.

A picture of Gregor Mendel holding a pea plant.

From the American Philosophical Society Library.

Molecular Genetics (Chapters 16–20)

Molecular genetics is based on the work of James Watson and Francis Crick.

A picture of James Watson and Francis Crick in front of a model of the DNA double helix.

From the website for the International Congress of Genetics.