Again:-

“It is inexplicable, on the theory of creation, why a part developed, &c., . . .  But, on my view, this part has undergone,” &c. (p. 474).

“On my view” became “on our view” in 1869.

Again:-

“Glancing at instincts, marvellous as some are, they offer no greater difficulty than does corporeal structure on the theory of the natural selection of successive, slight, but profitable modifications” (p. 474).

Again:-

“On the view of all the species of the same genus having descended from A common parent, and having inherited much in common, we can understand how it is,” &c. (p. 474).

Again:-

“If we admit that the geological record is imperfect in an extreme degree, then such facts as the record gives, support the theory of descent with modification.

" . . .  The extinction of species . . . almost inevitably follows on the principle of natural selection” (p. 475).

The word “almost” has got a great deal to answer for.

Again:-

“We can understand, on the theory of descent with modification, most of the great leading facts in Distribution” (p. 476).

Again:-

“The existence of closely allied or representative species in any two areas, implies, on the theory of descent with modification, that the same parents formerly inhabited both areas . . .  It must be admitted that these facts receive no explanation on the theory of creation . . .  The fact . . . is intelligible on the theory of natural selection, with its contingencies of extinction and divergence of character” (p. 478).

Again:-

“Innumerable other such facts at once explain themselves on the theory of descent with slow and slight successive modifications” (p. 479).

“Any one whose disposition leads him to attach more weight to unexplained difficulties than to the explanation of a certain number of facts, will certainly reject my theory” (p. 482).

“My theory” became “the theory” in 1869.

From this point to the end of the book the claim is so ubiquitous, either expressly or by implication, that it is difficult to know what not to quote.  I must, however, content myself with only a few more extracts.  Mr. Darwin says:-

“It may be asked how far I extend the doctrine of the modification of species” (p. 482).