The point which seems to me strong is that all naturalists admit that there is a natural classification, and it is this which descent explains.

I wish you had insisted a little more against the "North British" (203/5.

At page 485 Mr.Wallace deals with Fleeming Jenkin's review in the "North British Review," 1867.

The review strives to show that there are strict limits to variation, since the most rigorous and long-continued selection does not indefinitely increase such a quality as the fleetness of a racehorse.

On this Mr.Wallace remarks that "this argument fails to meet the real question," which is, not whether indefinite change is possible, "but whether such differences as do occur in nature could have been produced by the accumulation of variations by selection.") on the reviewer assuming that each variation which appears is a strongly marked one; though by implication you have made this very plain.