Origin of Species Variorum

→ in 1869

with comparative suddenness in 1872

→ can also be shown that the production of the two sorts of flowers by 1869

is a distinct question how 1866

is, however, probable that the two sorts of flowers borne by 1872

→ has been effected by finely graduated steps. 1869

has come to produce two kinds of flowers; but it can be shown in some cases to be probable, and in other cases to be almost certain, that this has been effected by finely graduated steps. 1866

were originally differentiated by finely graduated steps, which may still be followed in some few cases. 1872

→ individual may simultaneously perform 1869

individual sometimes perform simultaneously 1866

organ under two very different forms, may simultaneously perform in 1872

→ function, 1866 1869

individual the same function, 1872

→ OMIT 1869 1872

having a ductus pneumaticus for its supply and 1866

→ partitions, and having a ductus pneumaticus for the supply of air. 1869 1872

partitions. 1866

→ groups, 1869 1872

genera or families, 1866

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

Two distinct organs sometimes perform simultaneously the same function in the same individual; to give one instance, there are fish with gills or branchiæ that breathe the air dissolved in the water, at the same time that they breathe free air in their swimbladders, this latter organ having a ductus pneumaticus for its supply, and being divided by highly vascular partitions.

→ for performing the same function might 1869

might with ease 1859 1860

might 1861

or means of performing the same function might 1866

might readily 1872

→ fish. 1869

fish, or, for I do not know which view is now generally held, a part of the auditory apparatus has been worked in as a complement to the swimbladder. 1859 1860 1861 1866

fishes. 1872

→ is no reason to doubt that the swimbladder 1869 1872

seems to me to be no great difficulty in believing that natural selection 1859 1860

seems to me to be no extreme difficulty in believing that natural selection 1861 1866

be effected →in the character of the species. It →can also be shown that the production of the two sorts of flowers by the same plant →has been effected by finely graduated steps. Again, two distinct

organs,

organs

the same →individual may simultaneously perform the same →function, and this is

an extremely

a highly

important means of transition: to give one

instance,—

instance,—there

there are

are

fish with gills or branchiæ that breathe the air dissolved in the water, at the same time that they breathe free air in their swimbladders, this latter organ →OMIT being divided by highly vascular →partitions, and having a ductus pneumaticus for the supply of air. To give another instance from the vegetable kingdom: plants climb by three distinct means, by spirally twining, by clasping a support with their sensitive tendrils, and by the emission of

aërial

rootlets; these three means are usually found in distinct →groups, but some few

species

plants

exhibit two of the means, or even all three, combined in the same individual. ↑ In

these

all such

cases,

cases

one of the two organs →for performing the same function might be modified and perfected so as to perform all the

work

work,

by itself,

....

being aided during the

process

progress

of modification by the other organ; and then this other organ might be modified for some other and quite distinct purpose, or be

quite

wholly

obliterated.

The illustration of the swimbladder in fishes is a good one, because it shows us clearly the highly important fact that an organ originally constructed for one

pur- pose,

purpose,

namely,

namely

flotation, may be converted into one for a

wholly

widely

different purpose,

namely,

namely

respiration. The

swim-bladder