Origin of cultivated plants / by Alphonse de Candolle.

  • Alphonse Pyramus de Candolle
Date:
1884
Catalogue details

Licence: Public Domain Mark

Credit: Origin of cultivated plants / by Alphonse de Candolle. Source: Wellcome Collection.

    29/532
    tropics, have been once naturalized; that is to say, they have, from geographical and physical circumstances, passed from one region to another. When, in 1855, I put forward the idea that conditions anterior to our epoch determined the greater number of the facts of the actual distribution of plants—this was the sense of several of the articles, and of the conclusion of my two volumes of geographical botany 1—it was received with considerable surprise. It is true that general considera- tions of palaeontology had just led Dr. Unger,2 a German savant, to adopt similar ideas, and before him Edward Forbes had, with regard to some species of the southern counties of the British Isles, suggested the hypothesis of an ancient connection with Spain.3 But the proof that it is impossible to explain the habitations of the whole number of present species by means of the con- ditions existing for some thousands of years, made a greater impression, because it belonged more especially to the department of botanists, and did not relate to only a few plants of a single country. The hypothesis suggested by Forbes became an assured fact and capable of general application, and is now a truism of science. All that is written on geographical or zoological botany rests upon this basis, which is no longer contested. This principle, in its application to each country and each species, presents a number of difficulties; for when a cause is once recognized, it is not always easy to dis- cover how it has affected each particular case. Luckily, so far as cultivated plants are concerned, the questions which occur do not make it necessary to go back to very ancient times, nor to dates which cannot be defined by a given number of years or centuries. No doubt the modem specific forms date from a period earlier than the great extension of glaciers in the northern hemi- ' Alph. do Candolle, Qdographie Botanique Raisonnde, clmp. x. p. 10d5 ; chap, xi., xix., xxvii. * ^'ger, Versuch einer Qeschichto der Pjlanzenwelt, 1852. Ioi'bes, On the Connection between the Distribution of the Existing Fauna and Flora of the British Isles, with the Geological Changes which have affected their Area, in 8vo, Memoirs of the Geological Survey, vol. i.