Gregor Mendel pod shape, unripe pod color, flower location, and plant height. He first focused on seed shape, which was either angular or round. Between 1856 and 1863 Mendel cultivated and tested some 28,000 plants, the majority of which were pea plants ("Pisum sativum"). This study showed that, when true-breeding different varieties were crossed to each other (e.g., tall plants fertilized by short plants), in the second generation, one in four pea plants had purebred recessive traits, two out of four were hybrids, and one out of four were purebred dominant. His experiments led him to make two generalizations, the Law of
Genetics and the Origin of Species to identify that some populations of this species did not have identical sets of genes. Dobzhansky used experimental breeding in laboratories and gardens, and also surveys related to species in nature to help support aspects of organic evolution. The data in his book show the different genetic mutations and chromosomal changes that were observed. These experiments are vital to this book because they illustrate a transition from the laboratory to the greater field of genetics. "Drosophila" enabled researchers to gain a deeper understanding of how scientific knowledge about heredity has expanded and contributed to other areas of biology. By focusing