Professor Wildenow was one of the fitst who adopted this
hypothesis ; and he maintained it under a particular modification.
Wildenow multiplied the Linnsean centres of creation.
He perceived that it was impossible- to account for
the phenomena by supposing one primary seat or birth-place
of all living creatures : he imagined that organization began
in many different foci,-all of which were on primitive
mountains, the first that were left dry by the waters of the
subsiding Ocean. On the higher tracts of these primitive mountains,
as soon as they became fitted to support vegetation,
Wildenow supposed that all the plants which have since
existed were first produced : as the surface of the ocean gist-
dually lowered itself, the different tribes of the vegetable
creation found room to extend themselves , on every side;
and they descended by degrees from the . heights into the
plains. In these, according to the opinion of Wildenow, are
to be found only such species as may be traced to: the. feet of
the nearest mountains, and it is thus possible, by different
mountain-ranges, to divide the flora of 'one region from
that of another.*
In this representation there is some truth, but scarcely
sufficient foundation for such an hypothesis; It has been
well observed by Rudolph!, that a person who has once
ascended the Alps may easily remember how the vegetation 1
assumed a new character from stage to stage. Instead of
recognising on the tops of the mountains, which are assumed
to be the original birth-places of vegetable tribes, a greafmul-
titude of the plants which form the vegetation of the plains,
assembled around their common centres, he finds in such
places very few species* and those of a peculiar character.
As he descends again to a lower- level, the multitude and
variety of plants increases, but in the vallies and* at the feet
of the hills, he loses sight of those mountain-tribes, supposed
to be the ancestral sources of all vegetation. As he proceeds
to the banks of rivers, to marshes, or salt-lakes, or to-the
sea-coast, or towards the dwellings of men, new vegetable
forms everywhere display themselves; no Alps, no moun-
* Wildenow—Grundriss der Krauterkunde.—Rudolphl über die Verbreitung
oder die angeblichen Wanderungen der Pflanzen.
tain-chains display the vegetation which belongs to the seashore
; but in the midst of the land, wherever salt-springs
break forth, the maritime tribes display themselves.”* These
observations ’oppose ' great .obstacles to our reception of
Wildenow^s hypothesis, that the primitive mountains of the
earth have been the original, centres of the vegetable creation.
It has been’further remarked by De Candolle,f that
without considering ithe - difficulty which wes experience in
tracing the proofs o f this doctrine, ©r-rather the want of any
evidence to establish it, great doubts exist whether the species
of plants which vegetate in the present day, arè to be identified
with those, Which grew in times, anterior to the origin
of vsecdndary formations* and of. which the impressions and
other remains are discovered in rocks of later date. Those
curious researches) but very lately, entered- upon with some
degree o f accuracy -by M. de Sternberg, and which M.
Adolphe- Brogniart gfready seems destine^i to-perfect, indicate
cfearly, as M. T)e Candolle has observed, that our-present
vegetable tribes are different- from the antediluvian species,
and consequently that theredias been a .new devefopemefit of
Vegetation- on the surface of the earth, subsequent to the
ere of the secondary formations. :
A gradual accumulation of facts obtained during late years,
in respect to the distribution of plants through different regions
of the earth lias laid open to naturalists new and important
points of view, from which- they have been enabled to .see
further into the real science of botanical geography. Th§
knowledge indeed, as yet acquired, of the whole * vegetable
creation; is: very far from being copapfel%i I t has been
calculated by M. De Candolle,' that the total aggregate of
vegetable species already described or observed in botanical
coUècticns, amounts to 5fi,000,J a number which he supposes
to be rather below than above the reality- After takings into
consideration the period of time which has elapsed since the
*' Rudolphi ubi supra, p.‘ISO. •
•f* De Candolle, Géographie Botanique, Diet, d’Histoire Naturelle.
$ De Candolle has explained hiss reasons for believing that the 27,000 species
ihdiêàM in Persoorrt Synopsis,may be'extënded bÿ a tnore accurate discrimination,
to 56,000. See Diet, des Sci. Nat. tom. xviii, p. 420.
c 2