[pages 255, 422]

It was not by chance that Darwin was a regular visitor at the Museum of Natural History in London, the location of the fundamental collection of museum exhibitions displaying the breeds of domesticated animals. It is hard to present a better picture of the striking amplitude of variability with respect to the breed of dogs than that located in the British Natural History Museum, which demonstrates the enormous possibilities opened up by reading.

When working during 1913 and 1914 in the personal library of Darwin, which was preserved in its entirety after his death and at that tiem was located in the Botany School of the University of Cambridge, where Darwin's son, Francis Darwin, was professor of plant physiology, and when looking over the large and beautifully selected collection of books- which was exceptionally large for that time - I had the opportunity to see how thoroughly Darwin studied the works of his forerunners with respect to the history of crops and the breeding of plants. Books by the best English, French, and German plant breeders and experts on cultivated plants such as Shireff, Le Coutère, Metzger and Loisleur-Deslongchamps were annotated with remarks by Darwin himself. (cf. the interesting Catalogue of the Library of Charles Darwin, compiled by H. W. Rutherford in 1908, and now in the Botany School, Cambridge). In the text and at the ends of books, Darwin noted down facts and ideas that were especially important to him. On the basis of his library it is, to a certain extent, possible to follow the course of the creativity of this great scientist and the enormously laborious work preceding his general conclusions.

In contrast to [Alphonse] DeCandolle, who was mainly interested in establishing the true native lands of cultivated plants on the basis of taxonomic-geographical, historical and linguistic data but also on the relationship between cultivated and wild plants, Darwin was first and foremost interested in the evolution of the species, the appearance of subsequent changes to which the species were subjected when taken into cultivation, the amplitude of the variability of the organisms under the influence of the conditions of cultivation and the role of selection. Unlike De Candolle, every plant interested Darwin, not only because of itself but as an integral unit for explaining evolution. Different species were, in essence, considered by Darwin as illustrations for the basic idea he wanted to argue. In contrast to the detailed codex of De Candolle, the book by Darwin on Variation of Plants and Animals under Domestication is of characteristic significance as a persistent idea towards a revelation of the dynamics of the evolutionary process.

Nikolai Ivanovich Vavilov (1887-1943), Russian geneticist.