Origin of Species Variorum

→ most crustaceans of all orders, 1869

the main body of crustaceans of all orders, 1866

most other crustaceans, 1872

→ in each he found it to differ in 1866 1869

he found it to differ in each in 1872

→ conditions, the variability of these crustaceans 1869

surrounding conditions, their variability 1872

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

Now, on the belief that species belonging to distinct families, already differing in some characters, and which whenever they varied would probably have varied in different manners, have been slowly adapted through natural selection to live more and more out of water and to breathe the air, it is quite intelligible, and might even have been con- fidently expected, that the structural contrivances thus acquired would in each case have materially differed, although serving for the same purpose.

→ as advanced by Fritz Müller, seems 1869

seems 1866 1872

→ this distinguished naturalist 1869

this distinguished naturalist fully 1866

Fritz Müller 1872

→ just discussed, we have seen that 1866 1869

we see the same end gained and the same function performed, 1872

→ more or less 1866 1869

not at all or only 1872

→ the same end is gained and the same function performed 1866 1869

OMIT 1872

accordance with the views advanced by me, be accounted for by inheritance from a common progenitor. But as the vast majority of the species in the above two families, as well as →most crustaceans of all orders, are aquatic in their habits, it is improbable in the highest degree, that their common progenitor should have been adapted for breathing air. Müller was thus led carefully to examine

and describe

....

the apparatus in the

few

....

air-breathing species; and →in each he found it to differ in several important points, as in the position of the orifices, in the manner in which they are opened and closed, and in some accessory details. Now such differences are intelligible, and might even have been

expected,

anticipated,

on the supposition that species belonging to distinct families had slowly become adapted to live more and more out of water, and to breathe the air. For these species, from belonging to distinct families, would

have differed

differ

to a certain extent, and in accordance with the principle that the nature of each variation depends on two factors, viz. the nature of the organism and that of the →conditions, the variability of these crustaceans assuredly would not have been exactly the same. Consequently natural selection would have had different materials or variations to work on, in order to arrive at the same functional result; and the structures thus acquired would almost necessarily have differed. ↑ On the hypothesis of separate acts of creation the whole case

must

remain

unintelligible,

and

can

only

say,

is.

This

line of

argument

argument,

→as advanced by Fritz Müller, seems to have had great weight in leading →this distinguished naturalist to accept the views maintained by me in this volume.

In the

foregoing

several

cases,

cases

→just discussed, we have seen that in beings →more or less remotely allied, →the same end is gained and the same function performed by organs in appearance, though not in

development,

truth,

closely similar.

But