Origin of Species Variorum

→ natural selection increased in successive generations 1859 1860 1861 1866 1869

OMIT 1872

→ its 1859 1860 1861 1866 1869

were increased during successive generations, its 1872

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

The evidence that accidental mutilations can be inherited is at present very scanty; but the remarkable case observed by Brown-Séquard of epilepsy produced by injuring the spinal chord of guinea-pigs, being inherited, should make us cautious.

→ There is not sufficient evidence to induce us to believe that mutilations are ever inherited; and I should prefer explaining 1859

There is not sufficient evidence to induce me to believe that mutilations are ever inherited; and I should prefer explaining 1860

So that it will perhaps be safest to look at 1861 1866

Hence it will perhaps be safest to look at 1869 1872

→ by the long-continued 1859 1860

as due to the long-continued 1861 1866

as due to the 1869

not as cases of inherited mutilations, but as due to the 1872

→ disuse in their progenitors; 1859 1860 1861 1866

long-continued disuse; 1869 1872

→ the tarsi are almost always lost in 1859 1860 1861 1866

OMIT 1869 1872

→ they must be lost 1859 1860 1861 1866

are generally found with their tarsi lost, this must happen 1869 1872

→ cannot 1859 1860 1861 1866

the tarsi cannot be of much importance or 1869 1872

→ much 1859 1860 1869 1872

of much importance or be much 1861 1866

→ inhabiting 1859 1860 1861

(but more are now known) which inhabit 1866 1869

(but more are now known) inhabiting 1872

quadrupeds. We may

believe

imagine

that the

~~early~~

early

progenitor of the ostrich

genus had

had

habits like those of

the

bustard, and

that,

that

as →natural selection increased in successive generations the size and weight of its

body

body,

→its legs were used more, and its wings less, until they became incapable of flight.

Kirby has remarked (and I have observed the same fact) that the anterior tarsi, or feet, of many male dung-feeding beetles are

~~very~~

very

often broken off; he examined seventeen specimens in his own collection, and not one had even a relic left. In the Onites apelles the tarsi are so habitually lost, that the insect has been described as not having them. In some other genera they are present, but in a rudimentary condition. In the Ateuchus or sacred

bettle

beetle

of the Egyptians, they are totally deficient. ↑ →There is not sufficient evidence to induce us to believe that mutilations are ever inherited; and I should prefer explaining the entire absence of the anterior tarsi in Ateuchus, and their rudimentary condition in some other genera, →by the long-continued effects of →disuse in their progenitors; for as →the tarsi are almost always lost in many dung-feeding

beetles

beetles,

→they must be lost early in

life;

life,

~~and~~

and

therefore →cannot be →much used by these insects.

In some cases we might easily put down to disuse modifications of structure which are wholly, or mainly, due to natural selection. Mr. Wollaston has discovered the remarkable fact that 200

beetles

beetles,

out of the 550 species →inhabiting

Madeira

Madeira,

are so far deficient in wings that they cannot fly; and

that,

that

of the twenty-nine endemic genera, no less than twenty-three

~~genera~~

genera

have all their species in this condition! Several