Classical genetics color, flower color and seed shape. Mendel took peas that had differing phenotypic characteristics and test-crossed them to assess how the parental plants passed the traits down to their offspring. He started by crossing a round, yellow and round, green pea and observed the resulting phenotypes. The results of this experiment allowed him to see which of these two traits was dominant and which was recessive based upon the number of offspring with each phenotype. Mendel then chose to further his experiments by crossing a pea plant homozygous dominant for round and yellow phenotypes with a pea plant that was
Heredity to work (noticing that traits that were not expressed explicitly in the parent at the time of reproduction could be inherited, that certain traits could be sex-linked, etc.) rather than suggesting mechanisms. Darwin's initial model of heredity was adopted by, and then heavily modified by, his cousin Francis Galton, who laid the framework for the biometric school of heredity. Galton found no evidence to support the aspects of Darwin's pangenesis model, which relied on acquired traits. The inheritance of acquired traits was shown to have little basis in the 1880s when August Weismann cut the tails off many generations of