Origin of Species Variorum

→ OMIT 1872

in its nature), 1859 1860 1861 1866 1869

→ OMIT 1872

with each other, 1859 1860 1861 1866 1869

→ genera now living in the United 1869 1872

genera of these 1859 1860

endemic genera of the United 1861

genera naturally living in the United 1866

→ in any country struggled 1872

struggled 1859 1860 1861 1866 1869

→ OMIT 1872

of any country, 1859 1860 1861 1866 1869

→ of structure in 1872

in 1859 1860 1861 1866 1869

piece of ground, could live on it (supposing

its nature

not to be in any way

peculiar

peculiar),

→OMIT and may be said to be striving to the utmost to live there; but, it is seen, that where they come into the closest

competition

competition,

→OMIT the advantages of diversification of structure, with the accompanying differences of habit and constitution, determine that the inhabitants, which thus jostle each other most closely, shall, as a general rule, belong to what we call different genera and orders.

The same principle is seen in the naturalisation of plants through

mans

man's

agency in foreign lands. It might have been expected that the plants which

have

would

succeeded

succeed

in becoming naturalised in any land would generally have been closely allied to the indigenes; for these are commonly looked at as specially created and adapted for their own country. It

might,

might

also,

perhaps

perhaps,

have been expected that naturalised plants would have belonged to a few groups more especially adapted to certain stations in their new homes. But the case is very different; and Alph.

Candolle has well

remarked

remarked,

in his great and admirable work, that floras gain by naturalisation, proportionally with the number of the native genera and species, far more in new genera than in new species. To give a single instance: in the last edition of Dr. Asa

Grays

Gray's

Manual

'Manual

of the Flora of the Northern United

States,

States,'

260 naturalised plants are enumerated, and these belong to 162 genera. We thus see that these naturalised plants are of a highly diversified nature. They differ, moreover, to a large

extent

extent,

from the indigenes, for out of the 162

genera,

naturalised genera,

no less than 100 genera are not there indigenous, and thus a large proportional addition is made to the →genera now living in the United States.

By considering the nature of the plants or animals which have →in any country struggled successfully with the

indigenes

indigenes,

→OMIT and have there become naturalised, we

can

may

gain some crude idea in what manner some of the natives would have

had

....

to be modified, in order to

have gained

gain

an advantage over

the

....

other

their

natives;

compatriots;

and we

may,

may

I think,

....

at least

safely

....

infer that diversification of structure, amounting to new generic differences, would

have been

profitable to them.

The advantage of diversification →of structure in the inhabitants of the same region is, in fact, the same as that of the physiological division of

labour

labor

in the organs of the same individual body— a subject so well elucidated by Milne Edwards. No physiologist doubts that a stomach

by being

....

adapted to digest vegetable matter alone, or flesh alone, draws most nutriment from these substances. So in the general economy of any land, the more widely and perfectly the animals and plants are diversified for different habits of life, so will