Experiments on Plant Hybridization

Written in 1865 by Gregor Mendel, Experiments on Plant Hybridization (German: Versuche über Pflanzen-Hybriden) was the result after years spent studying genetic traits in pea plants. Mendel read his paper to the Natural History Society of Brünn (Brno) on February 8 and March 8, 1865. It was published in the Proceedings of the Society the following year.

In his paper, Mendel compared seven discrete characters:

• Color and smoothness of the seeds (grey and round or white and wrinkled)
• Color of the cotyledons (yellow or green)
• Color of the flowers (white or violet)
• Shape of the pods (full or constricted)
• Color of unripe pods (yellow or green)
• Position of flowers and pods on the stems
• Height of the plants (short or tall)

Through experimentation, Mendel discovered that one inheritable trait would invariably be dominant to its recessive alternative. This model, later known as Mendelian inheritance or Mendelian genetics, provided an alternative to blending inheritance, which was the prevailing theory at the time. Mendel's work received little attention from the scientific community and was largely forgotten. It was not until the early 20th century that Mendel's work was rediscovered and his ideas used to help form the modern synthesis.

In 1936, the statistician R.A. Fisher used a chi-square test to analyze Mendel's data and concluded that Mendel's results with the predicted ratios were far too perfect, indicating that adjustments (intentional or unconscious) had been made to the data to make the observations fit the hypothesis. Later authors have claimed Fisher's analysis was flawed, proposing various statistical and botanical explanations for Mendel's numbers. It is also possible that Mendel's results are "too good" merely because he reported the best subset of his data — Mendel mentioned in his paper that the data was from a subset of his experiments.