Figure 7

Figure 8

In contrast to Darwin’s total lack of familiarity with Mendel’s work, Darwin’s theories did have a clear influence on Mendel’s ideas, although not in 1854–55, when Mendel started his experiments with peas. Mendel possessed the second German edition of The Origin, which was published in 1863. In his copy, he marked certain passages by lines in the margin and others by underlining parts of the text. Mendel’s markings show great interest in topics such as the sudden appearance of new varieties, artificial and natural selection, and differences between species. There is little doubt that reading The Origin had significantly affected Mendel’s own writing by 1866, since Mendel’s paper reflects in many places various aspects of Darwin’s concepts. For instance, in discussing the origin of heritable variation, Mendel wrote: