Forward genetics a bare minimum for the appearance of specific phenotypes. However, such initial screens were either incomplete as they were missing redundant loci and epigenetic effects, and such screens were difficult to undertake for certain phenotypes that lack directly measurable phenotypes. Additionally a classical genetics approach takes significantly longer. Gregor Mendel experimented with pea plant phenotypes and published his conclusions about genes and inheritance in 1865. Around the early 1900s Thomas Hunt Morgan was mutating Drosophila using radium and attempting to find heritable mutations Alfred Sturtevant later began mapping genes of Drosophila with mutations they had been following. In the 1990s
Franz Unger of botany at the University of Graz and also taught at the Joanneum (which became the Universalmuseum Joanneum and the Graz University of Technology); in 1850 professor of plant physiology in Vienna. In 1852 he travelled to Northern Europe and to the Orient. Unger retired in 1866 and lived on his farm near Graz. Unger was one of the major contributors to the field of paleontology, later turning to plant physiology and phytotomy. He hypothesized that (then unknown) combinations of simple elements inside a plant cell determine plant heredity and greatly influenced the experiments of his student Gregor Johann Mendel.