"Under the relation of the earth as existing to-day, life would again be developed, if we were in a condition instantaneously to annihilate all life; yet the same results would not be produced as in the original period, because the needed materials are no longer present in the mighty masses, nor in the requisite fluid and gaseous conditions to attain so powerful effects, to which belong also as necessary conditions the far higher temperature and the greater humidity of the atmosphere of that epoch. In the first creative period the force as well as the material were present in colossal measure and then arose those gigantic plants and animals, which laid the foundation for all later organisms. Without the colossal ferns and lichens and palm-like growths of the early ages, the plants of to-day would have been impossible, and without the monstrous giant creatures of old, which became more and more refined through gradual adaptation to altered relations, the modern animal kingdom could not have arisen. This adaptation is one of the most wonderful phenomena in the history of the development of the earth and is found as well in the realm of plants as in that of animals. Originally there were only aquatic animals, but as the relations changed so that it became necessary, partly for the procuring of food and partly for the safety of the offspring, that animals should go on land, their attempts constantly repeated to do so, gradually produced a change in the limbs fitted for motion, and so came about the transformation of fins into wings in the creatures that wanted to rise out of the water into the air, which then had far more carrying power than at the present day.