stylistic:style_transfer, quality:corruption, stylistic:tone, structural:expansion
Johannsen's "pure line" experiments, 1903

In the early 1900s, Darwin's mechanism of natural selection was understood by believers in continuous variation, principally the biometricians Walter Weldon and Karl Pearson, to be able to work on a continuously varying characteristic, whereas de Vries argued that selection on such characteristics would be ineffective. Wilhelm Johannsen 's "pure line" experiments on Phaseolus vulgaris beans appeared to refute this mechanism. Using the true-breeding Princess variety of bean, carefully inbred within weight classes, Johannsen's work appeared to support de Vries. The offspring had a smooth random distribution. Johanssen believed that his results showed that continuous variability was not inherited, so evolution must rely on discontinuous mutations, as de Vries had argued. Johanssen published his work in Danish in a 1903 paper Om arvelighed i samfund og i rene linier (On inheritance in populations and in pure lines), and in his 1905 book Arvelighedslærens Elementer (The Elements of Heredity).