Here again the claim to the theory of descent with modification is unmistakable; it cannot, moreover, but occur to us that if species “have been produced by ordinary generation,” then ordinary generation has as good a claim to be the main means of originating species as natural selection has.  It is hardly necessary to point out that ordinary generation involves descent with modification, for all known offspring differ from their parents, so far, at any rate, as that practised judges can generally tell them apart.

Again:-

“We see in these facts some deep organic bond, prevailing throughout space and time, over the same areas of land and water, and independent of their physical condition.  The naturalist must feel little curiosity who is not led to inquire what this bond is.

“This bond, on my theory, is simply inheritance, that cause which alone,” &c. (p. 350).

This passage was altered in 1869 to “The bond is simply inheritance.”  The paragraph concludes, “On this principle of inheritance with modification, we can understand how it is that sections of genera . . . are confined to the same areas,” &c.

Again:-

“He who rejects it rejects the vera causa of ordinary generation,” &c. (p. 352).

We naturally ask, Why call natural selection the “main means of modification,” if “ordinary generation” is a vera causa?

Again:-

“In discussing this subject, we shall be enabled at the same time to consider a point equally important for us, namely, whether the several distinct species of a genus, which on my theory have all descended from A common ancestor, can have migrated (undergoing modification during some part of their migration) from the area inhabited by their progenitor” (p. 354).

The words “on my theory” became “on our theory” in 1869.

Again:-

“With those organic beings which never intercross (if such exist) the species, on my theory, must have descended from A succession of improved varieties,” &c. (p. 355).

The words “on my theory” were cut out in 1869.

Again:-

“A slow southern migration of a marine fauna will account, on the theory of modification, for many closely allied forms,” &c. (p. 372).

Again:-

“But the existence of several quite distinct species, belonging to genera exclusively confined to the southern hemisphere, is, on my theory of descent with modification, a far more remarkable case of difficulty” (p. 381).

“My” became “the” in 1866 with the fourth edition.  This was the most categorical claim to the theory of descent with modification in the “Origin of Species.”  The “my” here is the only one that was taken out before 1869.  I suppose Mr. Darwin thought that with the removal of this “my” he had ceased to claim the theory of descent with modification.  Nothing, however, could be gained by calling the reader’s attention to what had been done, so nothing was said about it.