Species

92 Species

the same founding group. Genera are thus established with closely similar species,

and are given with no formal and precise denition of classifying rules, especially

in the natural method.^200

Of the Linnaean scheme, he says merely that the nomenclature is useful, a matter

of convenience: “the species name must be both simple and easy, but it must also

sig n i f y,”^201 and “It is one thing to name a plant, another to describe it.”^202

Like Linnaeus, Jussieu held that plants have afnities like regions on a geographi-

cal map. The natural method

links all kinds of plants by an unbroken bond, and proceeds step by step from sim-

ple to composite, from the smallest to the largest in a continuous series, as a chain

whose links represent so many species or groups of species, or like a geographical

map on which species, like districts, are distributed by territories and provinces and

kingdoms.^203

However, as Stevens observes, the geography was becoming sparser in the regions
occupied.^204 Where for Linnaeus, the entire territory was more or less lled, for
Jussieu, there were large unoccupied regions, and for Charles-François Brisseau de
M i rb el (1776 –1854)^205 and Alphonse de Candolle the groupings become discrete and
separate.

Charles Bonnet and the Ideal Morphologists

Bonnet (1720–1793) was a Swiss (Genevan, as Switzerland did not then exist as
such) zoologist who was greatly inuenced by Leibniz’s ideas about the continuity
of nature (the lex continui) and he produced the classical ladder of nature as a result,
rst in his Traité d’insectologie,^206 and then in his Contemplation de la nature.^207
His ladder was envisaged as an articial system of ranking things in terms of their
progression, although he did so, he said, without “presuming to establish the pro-
gressive order of Nature.” The ladder ran from sh to birds to quadrupeds, and each
division itself was further divided: birds into aquatic, amphibious, and terrestrial,
and so forth (Figure 3.5).
Bonnet’s Échelle des êtres naturels, as he called it, implied that extant species
were the current forms of “extinct” species, but that we can only diagnose the mod-
ern forms in terms of their reproduction of like forms. Like the early Buffon, he
effectively denied the reality of species considered as essences, and plumped for a
nominalistic individualist conception:

(^200) Jussieu, loc cit. Italics original. Translation by Laurent Penet, and revised by the author.
(^201) Jussieu 1964, 344.
(^202) Jussieu 1964, 510n115.
(^203) Jussieu 1964, 355.
(^204) Stevens 1994, 74ff.
(^205) M i rbel 1815.
(^206) Bon net 1745.
(^207) Bonnet 1764, cf. Stresemann 1975, 172.