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contrast between Humboldt’s and de Candolle’s attempt is striking. Whereas Humboldt proposes to use plant form, de Candolle opts to use:

      1) Temperature, as determined by distance from the equator, height above sea level and southern or northerly exposure.

      3) The degree of soil tenacity or mobility (de Candolle, cited in Ebach and Goujet 2006, p. 768).

Schematic illustration of the third edition of Flore Française.

      Figure 1.3. Carte Botanique de France, pour la 3e Edition de la Flore française par A.G. Dezauche fils Ingénieur Hydrogéologue de la Marine an 13 (1805) “Botanical map of France for the 3rd Edition of Flore française by A.G. Dezauche the son, Marine Hydrological Engineer on the 13th year of the Revolution (1805)” (see Ebach and Goujet 2006, Figure 1.1). For a color version of this figure, see www.iste.co.uk/guilbert/biogeography.zip

      The method proposed by de Candolle did not catch on, and by 1820 de Candolle had chosen to use plant distributions instead, dividing the world into 20 regions:

      Again, de Candolle’s plant regions failed to find acceptance. Humboldtian Joakim Frederik Schouw dismissed the regions:

      Candolle compares 20 floras, or as he calls them, regions. In his method, which he has developed studying these floras, [Candolle] does not reveal the characteristics that each form takes; it appears that the main basis for the division [of the regions] is current distributions (Schouw 1823, p. 504, my translation).

      So too did his son Alphonse de Candolle, who considered “artificial systems”, which are a detriment to science “when they are considered to be natural” (de Candolle 1855, pp. 1304–1305). So what then is a natural region?

      The Humboldtians believed that both biotic and abiotic factors, such as climate, were vital in recognizing plant forms and plant regions:

      To have an exact acquaintance with these principal forms of vegetation is of the greatest importance to a phyto-geographical division of the globe, as they principally fix the natural physiognomy of different countries. Humboldt is the first who has made such a classification of vegetation, and this must be taken as the foundation of all further inquiry into the subject. It is not until we are somewhat intimately acquainted with the various characteristic forms of plants, that we will be able to recognise the peculiarities of each flora, and to characterise the physiognomy of each country (Meyen 1846, p. 106).

      One idea mentioned by de Candolle (1820) was adopted by the Humboldtians, namely, that of stations and habitations (see Nelson 1978):

      By the term station I mean the special nature of the locality in which each species customarily grows; and by the term habitation, a general indication of the country wherein the plant is native. The term station relates essentially to climate, to the terrain of a given place; the term habitation relates to geographical, and even geological, circumstances … The study of stations is, so to speak, botanical topography; the study of habitations, botanical geography … The confusion of these two classes of ideas is one of the causes that have most retarded the science, and that have prevented it from acquiring exactitude” (de Candolle 1820, p. 383, translated in Nelson 1978, p. 280)3.

      1.2.4. Zoogeography: a search for natural regions

      Animal geography had a later start than plant geography. Although Zimmermann (1778–1783) was the first to consider an animal geography, it was confined to quadrupeds. Unlike the Humboldtians and de Candolle, animal geographers rarely looked at faunal regions, instead preferring to look at taxon-specific distributions. Also, a contemporary of Zimmermann, Johan Christian Fabricius, proposed eight climatic regions “from which the Stations of insects are judged” (Fabricius 1778, p. 154). Zoologists did not adopt the Humboldtian tradition of using “form” and dismissed the climatic regions of Fabricius as arbitrary or artificial:

      This simple statement is enough to convince us that there is a lot of arbitrariness in these divisions (Latreille 1815, pp. 40–41, my translation).

      [Fabricius] … by not attempting to demonstrate the correctness of any one of his divisions, seems to have subsequently abandoned them altogether, since no one, it may be fairly presumed, was more qualified than himself to discover the artificial nature of his theory (Swainson 1835, pp. 10–11).

      Similarly, the regions proposed by Pierre André Latreille in 1817, based on latitudinal and longitudinal gradients along climatic zones, were equally dismissed:

      Any division of the globe into climates, by means of equivalent parallels and meridians, wears the appearance of an artificial and arbitrary system, rather than to one according to nature (Kirby and Spence 1828, p. 487).

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