CHAPTER II.
OF THE DISPERSION OF PLANTS, AND OF-i THE PRIMARY
HABITATIONS OF INDIVIDUAL SPECIES.
S e c t io n I.—Three hypotheses which have been maintained
o nthis subject.
There are only^ three conjectureras to the originsri habitations,
and the dispersion of Plants, which can be thought in
a n y degree probable; They a re ,.
First, That^all species of Plants whatever had ihmOm-
mon their primary seat in one particular region, whence
they have been subsequently spread into the Gauntries where
they are now found.
Secondly, That every species or distinct tribe ^nithe^yegfè“
table creation, originated from one particular centre» or birth-
pfeee> but that the primary habitations rilkdifïerent species
were in different regions of the earth.
Thirdly, I t has beemcoTqecturedthaLthevegetabl© tribes
are spread , over the surface of the globe,, .underi veri; from any
particular local origins, or centres of propagation ; and that
plants of : every kind have • been brought i#Ritâe®ii,ea^§
wherever all the conditions were to be found which fav c^ed
their developement. According to this notion, particular
tribes may have been, from the beginning of their existence,
as widely diffused as they are at the present day-; nor. is it
necessary, when we find the same. species in two distant
places, to inquire how it was conveyed; from one to the
other. Writers who adopt this opinion* suppose that plants
were always to be found nearly in the sites where they now
exist ; anTexception being made in regard to certain species,
which have been either designedly or accidentally conveyed
by men from one country into another. ■
Each o f these three opinions has found supporters among
naturalists of high reputation.
. Linnaeus embraced and defended the first of these suppositions;;
He conjectured that the habitable world was limited
during the first nage td one regionoof no great extent ;
the Sourly " tract in vtte$ surface' of ■ our planet, which had
boon; as ÿet laid bare - by the, subsidence of the primeval
ocean! I In thiskfeftilé ^ p ot;were jéqn^reg.ated the originals of
all the species1 tiof? plants /which haVelKsiineee/existed on th e
eart%4tOSe|fe^r with* >lh^ first' ancestors of .all animals and of
the human race# f‘ilia^quâncqmmôde habitaverint animalia
omnia et^yè^elabilia læte.' germinaverini.” In order to ae-
coniodat^tlsév various thkbitud|ä|of- Soil^aany organized, bèings
and to providte à diversity .of,» donates suited* tô, their several
natures, Linnseus imagined this common - bir,th-plade of all
livinff'CreatUFeEftoi have been situated in some-warm region
of the earth", which; contained a loftymountain-rahgèjj|( on «the
heights^atad;4n, the hollows and declivities; qf-it-his, wereftp.be
found aH' temperatures and every dime, fjrom t i e torrid to
that % th e frozen zone.*
j^B.hcba-n imaginaryischeme is more allied to poetry or fiction;
thanflofa serious Investigation of the phenomena pfi naturel
The hypothesis!;of Linnæus is irreconcilable with the facts
most ^gënerally known 1 änd ; established- with |regard-; to the
distribution o f Plants.'
Botanists of the present“ day are divided between the. two
last* of the'three conjectures.which I have stated. Rudplphi;
who-is Mlowed by. mariy writers; has contended stronglyin
favour of- th e position that .the same external agencies-, the
same! (Conditions of climate, sj>$l, moisture, atmosphere,’ and
geographical situation, never fail to-call, into, existence, or to
be found in local connexion with plants - of the same kinds,
without reference to the means or- possibilities., n f the transmigration
of species from one region to another.-f* Others
find reasons for concluding that there were given to all the
vegetable tribes original centresiof, their existence; and they
even seek, in the càse of any particular species; a spot where it
was first produced, and whence it has been spread.. -
* De Telluris habitabilis increment«». in Amoenitat. Academ.
+ Rùdolphi’s Beyträge zur Anthropologie und allgemeinen Naturgeschichte.
3. Ueber die Verbreitung der Organischen Körper.
ü