Secondly. Animals found in islands situated near to continents
are generally of the stock which belongs to the main
lands. This remark will apply to the British and Mediterranean
isles, and to all islands so situated of which the
zoology has been explored.
S e c t io n IX.—General Inferences from Facts relating to. the
dispersion o f Organised Beings—Bearing o f the Conclusion
obtained on the History o f Mankind.
I have gone over the different series of facts connected
with the dispersion of organized beings, both plants and animals,
as extensively as it appeared necessary to do. ! I fear indeed
that some-of my readers may have thought the preceding
details too particular and diffuse. To me it appeared so important
to establish on a broad groundwork the inference
which I am about to deduce, th at I have chosen to incur the
risk of being too minute, rather than that of leaving any
thing uncertain that could be elucidated by research.
There appears to have resulted from the foregoing inquiry,
sufficient evidence to establish one out of the three hypothetical
statements which were expressed a t the commencement
of this investigation, and -to show that the other two are irreconcilable
with the phenomena of Nature. -
1. The hypothesis of Linnaeus, that all races of plants and
animals originated in one common centre, or in onè limited
tract, involves difficulties, which in the present state of our
knowledge amount to physical impossibilities. It is contradicted
by the uniform tenour of facts, both in . botany and
zoology.
2. The second hypothesis, which supposes the same species
to have arisen from many different origins, or to have been
at the period of their first existence generally diffused over
separated countries, is also irreconcilable with facts. It does
not appear that Nature has everywhere called organized
beings into existence, where the physical conditions requisite
for their life and growth were to be found.
3. The inference to be collected from the facts at present
known, seems to be as follows the various tribes of organized
beings were originally placed by the Creator in certain
regions, for which they are by their nature peculiarly adapted.
Each species had only" one beginning in a single stock; probably
a single pair, as Linnseus supposed, was first called
into being in some particular * spot, and the progehy left to
disperse themselves to as great a distance from the original
centre of their existence, as the locomotive powers bestowed
on them, or their capability of bearing changes of climate,
and other physical agencies, may have enabled them to
wander.
The bearing of this general conclusion on the inquiries
hereafter to be pursued is sufficiently obvious. We have now
to investigate the question, whether all the races of men afe
of one species in the zoological sense, or of'several distinct
species. I f it should be found that there is only tone human
species in existence, the universal analogy pf? the organized
world would lead us to the conclusion, that there i^ o n ly one
human race, or t h ^ all mankind are descended.'from one
stock. It is the more improbable that a plurality, of races
exist in one species with reference to man than with regard
to any inferior tribe, as the locomotive< powers of mankind,
those of brute animals.