Origin of Species Variorum

→ the alimentary canal respires, digests, and excretes 1859 1860 1861 1866 1869

OMIT 1872

→ Cobites. 1859 1860 1861 1866 1869

Cobites the alimentary canal respires, digests, and excretes. 1872

→ a part or 1859 1860 1861

the whole or part of an 1866 1869 1872

→ wholly change its nature 1859 1860 1861

greatly change its nature 1866

OMIT 1869 1872

→ steps. 1859 1860 1861 1866

steps greatly change its nature. 1869 1872

numerous, successive, slight modifications, my theory would absolutely break down. But I can find out no such case. No doubt many organs exist of which we do not know the transitional grades, more especially if we look to much-isolated species, round which, according to

the

theory, there has been much extinction. Or again, if we

take

look to

an organ common to all the members of a

~~large~~

large

class, for in this latter case the organ must have been

originally

first

formed at

an extremely

remote period, since which all the many members of the class have been developed; and in order to discover the early transitional grades through which the organ has passed, we should have to look to very ancient ancestral forms, long since become extinct.

We should be extremely cautious in concluding that an organ could not have been formed by transitional gradations of some kind. Numerous cases could be given amongst the lower animals of the same organ performing at the same time wholly distinct functions; thus →the alimentary canal respires, digests, and excretes in the larva of the dragon-fly and in the fish →Cobites. In the Hydra, the animal may be turned inside out, and the exterior surface will then digest and the stomach respire. In such cases natural selection might

easily

....

specialise, if any advantage were thus gained, →a part or organ, which had

previously performed

performed

two functions, for one function alone, and thus →wholly change its nature by insensible →steps. Certain plants, as some Leguminosæ, Violaceæ, &c., bear two kinds of flowers; one having the normal structure of the order, the other kind being degraded, though sometimes more fertile than the perfect kind: if the plant ceased to bear its perfect flowers, and this did occur during several years with an imported specimen of Aspicarpa in France, a great and sudden transition would apparently be effected in the