Mendel's experiments on plant hybrids

Gregor Mendel, born in the farming village of Hynčice, entered the Augustinian Abbey of St Thomas in Brno in 1843 and was ordained a priest in 1847. In 1856 he began crossing garden peas in the monastery garden. He chose the genus Pisum because its varieties had constant traits that were easy to tell apart, their hybrids were fully fertile, and stray pollen seldom interfered: among more than 10,000 plants he examined closely, contamination turned up only a few times.

He crossed varieties that differed in single traits, such as round against wrinkled seeds or yellow against green, and recorded every generation. In the hybrids one form of a trait showed while the other stayed hidden, and in the next generation both appeared again in a regular proportion. From 253 hybrid plants he harvested 7,324 seeds, 5,474 round and 1,850 wrinkled, a ratio of 2.96 to 1. For seed color, 8,023 seeds from 258 plants divided into 6,022 yellow and 2,001 green, or 3.01 to 1.

Mendel read the work to the Natural History Society of Brünn at its meetings of 8 February and 8 March 1865, and the society printed it in its proceedings in 1866. By then, he wrote, the experiment had run for eight years and was essentially finished.

The paper went almost unnoticed while he lived. Mendel died in 1884, and other scientists rediscovered his results at the turn of the twentieth century; the traits he counted are now explained by discrete units of inheritance called genes, some dominant and some recessive.