Again:-

“I believe that something more is included, and that propinquity of descent—­the only known cause of the similarity of organic beings—­ is the bond, hidden as it is by various degrees of modification, which is partially revealed to us by our classification” (p. 418).

Again:-

“Thus, on the view which I hold, the natural system is genealogical in its arrangement, like a pedigree” (p. 422).

“On the view which I hold” was cut out in 1872.

Again:-

“We may feel almost sure, on the theory of descent, that these characters have been inherited from a common ancestor” (p. 426).

Again:-

“On my view of characters being of real importance for classification only in so far as they reveal descent, we can clearly understand,” &c. (p. 427).

“On my view” became “on the view” in 1872.

Again:-

“The more aberrant any form is, the greater must be the number of connecting forms which, on my theory, have been exterminated and utterly lost” (p. 429).

The words “on my theory” were excised in 1869.

Again:-

“Finally, we have seen that natural selection. . .  Explains that great and universal feature in the affinities of all organic beings, namely, their subordination in group under group.  We use the element of descent in classing the individuals of both sexes, &c.; . . .  We use descent in classing acknowledged varieties; . . . and I believe this element of descent is the hidden bond of connection which naturalists have sought under the term of the natural system” (p. 433).

Lamarck was of much the same opinion, as I showed in “Evolution Old and New.”  He wrote:- “An arrangement should be considered systematic, or arbitrary, when it does not conform to the genealogical order taken by nature in the development of the things arranged, and when, by consequence, it is not founded on well-considered analogies.  There is a natural order in every department of nature; it is the order in which its several component items have been successively developed.” {195a} The point, however, which should more particularly engage our attention is that Mr. Darwin in the passage last quoted uses “natural selection” and “descent” as though they were convertible terms.

Again:-

“Nothing can be more hopeless than to attempt to explain this similarity of pattern in members of the same class by utility or the doctrine of final causes . . .  On the ordinary view of the independent creation of each being, we can only say that so it is . . .  The explanation is manifest on the theory of the natural selection of successive slight modifications,” &c. (p. 435).