Origin of Species Variorum

→ thus to differ 1872

to be thus affected 1869

↑ 5 blocks not present in 1859 1860 1861 1869 1872; present in 1866

In one case difference in food was accompanied by several slight but constant structural differences in the mature male alone. In other cases both males and females are thus slightly affected. Lastly, differences of food apparently cause more marked and constant differences in colour or structure, or in both combined, in the larva and in the mature insect. Forms modified to this degree are ranked by all entomologists as distinct, though allied, species of the same genus. The slighter differences, as in colour alone, and confined to the larva alone, to the mature insect alone, are almost invariably looked at as mere varieties.

→ determine for another, 1872

draw the line for others, 1866

determine for others, 1869

→ OMIT 1869 1872

and determine with certainly 1866

→ ought to be called species 1869 1872

to call varieties 1866

→ varieties. 1869 1872

to call species. 1866

↑ 1 blocks not present in 1859 1860 1861 1869 1872; present in 1866

Mr. Walsh, who argues with much force that the different states have gradually passed into each other, is forced to assume that those forms, which it may be supposed would freely intercross, should be designated as varieties, whilst those which have probably lost this capacity for intercrossing should be called species.

→ OMIT 1869 1872

in all these cases clearly 1866

→ it 1869 1872

intermediate links between the several forms thus produced 1866

→ that intermediate links connecting the several forms should now 1869 1872

to 1866

→ OMIT 1869 1872

of doubtful value, 1866

→ When, on the other hand, 1869 1872

But when 1866

→ good chance 1869 1872

chance, which is not rarely successful, 1866

→ OMIT 1869 1872

go so far as to 1866

→ is certain 1872

cannot, however, be disputed 1866

→ to be varieties, resemble species so completely in character, 1872

as varieties, have so perfectly the character of species 1866

→ they ought to be 1869 1872

such slightly different forms are rightly 1866

→ rank; but space does not here permit me to discuss them. 1866 1869 1872

rank. 1859 1860 1861

→ no doubt bring 1872

bring 1866 1869

→ them. 1872

forms of doubtful value. 1866 1869

in the nature of their secretions. In some instances the males alone, in other instances both males and females, have been observed →thus to differ in a slight degree. When the differences are rather more strongly marked, and when both sexes and all ages are affected, the forms

would be

are

ranked by all entomologists as

species.

good species.

↑ But no

man

observer

can →determine for another, even if he can do so for himself, →OMIT which of

the several

these

phytophagic

Phytophagic

forms →ought to be called species and which →varieties. ↑ Mr. Walsh ranks the forms which it may be supposed would freely

intercross

intercross,

together,

....

as varieties; and those which appear to have lost this power, as species. As the

difference

differences

→OMIT

depends

depend

on the insects having long fed on

perfectly

....

distinct plants, →it cannot be expected →that intermediate links connecting the several forms should now be

found;

though

formerly

such

must

have

existed,

connecting

the

present

divergent

forms

with

their

common

progenitor.

The naturalist thus loses his best guide in determining whether to rank

such

....

doubtful forms as varieties or species. This likewise necessarily occurs with closely allied organisms, →OMIT which inhabit

separate

distinct

continents or

distant

....

islands. →When, on the other hand, an animal or plant ranges over the same

continent

continent,

or inhabits many islands in the same archipelago, and presents different forms in the different areas, there is always a →good chance that intermediate forms

may

will

be discovered which

shall

will

link together the extreme states; and these are then degraded to the rank of varieties.

Some few naturalists maintain that animals never present varieties; but then these same naturalists rank the slightest

differences

difference

as of specific value; and when

even

....

the

identically same

same identical

form is met with in two

distant

distinct

countries, or in two

distinct

....

geological formations, they →OMIT believe that two

separate

distinct

species are hidden under the same dress. The term species thus comes to be a mere useless

mental

....

abstraction, implying and assuming a separate act of creation. It →is certain that many forms, considered by highly-competent judges →to be varieties, resemble species so completely in character, that they have been

ranked

thus ranked

by other highly-competent

judges

good

and

true

species.

But to discuss whether →they ought to be called species or varieties, before any definition of these terms has been generally accepted, is vainly to beat the air.

Many of the cases of strongly-marked varieties or doubtful species well deserve consideration; for several interesting lines of argument, from geographical distribution, analogical variation, hybridism, &c., have been brought to bear

the attempt to determine their →rank; but space does not here permit me to discuss them. Close investigation, in many cases, will →no doubt bring naturalists to

an agreement

agree

how to rank doubtful forms. Yet it must be confessed that

it,

is in the best known countries that we find the greatest number of →them. I have been struck with the fact, that if any animal or plant in a state of nature be highly useful to man, or from any cause closely