(2) Second, _Natural Selection inevitably implies that, on searching the records of Evolution, we shall find only gradual change_, proceeding continually, so that the ascending organisms follow, as it were, regular inclined planes showing no steps. The whole of Evolution should, under Natural Selection, prove to be of this kind. Thus you would have, say, tigers as they are now, gradually developing out of some tiger-like ancestor in the past by a regular and uninterrupted process, never achieving a fixed type but perpetually changing as time went on; and that perpetual change would be still going on to-day. The world about us would not show (as it does) a vast number of strongly separate types but a confused jumble of forms all melting one into the other. (3) _Third_, Natural Selection presupposes Evolution through the killing off of individuals lacking certain advantages, _how then do other types continue still to be with us in spite of lacking these advantages?_ (4) Fourth, _Natural Selection must stand or fall of itself_. If you try to prop it up with Will or Design, inherent in the organism, or acting in any other fashion, you destroy its whole thesis. If you say, for instance, “the country becoming dryer, animals which _adapted themselves_ to the new conditions survived, and those that could not adapt themselves died out,” that is no example of Natural Selection _as an agent of Evolution_. For when you say “_Animals which adapted themselves_ to the new conditions,” you are presupposing some inherent power in the animal to adapt itself: you are presupposing a form of Will and Design, and thereby denying the purely mechanical action, the unintelligent “sieve,” of Natural Selection as an agent. (5) Fifth, _Natural Selection presupposes, quite gratuitously, that new survival values will be perpetually and progressively appearing_. That sheep woollier than the average of a flock have survival value as the winters get colder is obvious: too obvious to need stating. But why should the next generation, under mere chance, produce a number of new still woollier variations, and the one after that yet another even woollier set; and so on indefinitely? (6) Sixth, _Natural Selection presupposes that in every stage of the slow process of development by infinitesimal differences_, each _successive difference is more advantageous than the last and has a special survival value_.