When to these factors is added the effect upon the climate caused by the periodic rising of mountain chains, it is at once apparent that the lands must have had constantly varying climates. In general the temperature fluctuations seem to have been slight, but geographically the climates varied between mild to warm pluvial, and mild to cool arid. The arid factor has been of the greatest import to the organic world of the lands. Further, when to all of these causes is added the fact that during emergent periods the formerly isolated lands were connected by land bridges, permitting intermigration of the land floras and faunas, with the introduction of their parasites and parasitic diseases, we learn that while the climatic environment is of fundamental importance it is not the only cause for the more rapid evolution of terrestrial life.... Briefly, then, we may conclude that the markedly varying climates of the past seem to be due primarily to periodic changes in the topographic form of the earth’s surface, plus variations in the amount of heat stored by the oceans. The causation for the warmer interglacial climates is the most difficult of all to explain, and it is here that factors other than those mentioned may enter. Granting all this, there still seems to lie back of all these theories a greater question connected with the major changes in paleometeorology. This is: What is it that forces the earth’s topography to change with varying intensity at irregularly rhythmic intervals?... Are we not forced to conclude that the earth’s shape changes periodically in response to gravitative forces that alter the body-form?” _Evolution._ Modern evolution, or the theory of life continuously descending from life with change, may be said to have had its first marked development in Comte de Buffon (1707–1788), a man of wealth and station, yet an industrious compiler, a brilliant writer, and a popularizer of science. He was not, however, a true scientific investigator, and his monument to fame is his Histoire Naturelle, in forty-four volumes, 1749–1804. A. S. Packard in his book on Lamarck, his Life and Work, 1901, concludes in regard to Buffon as follows: “The impression left on the mind, after reading Buffon, is that even if he threw out these suggestions and then retracted them, from fear of annoyance or even persecution from the bigots of his time, he did not himself always take them seriously, but rather jotted them down as passing thoughts.... They appeared thirty-four years before Lamarck’s theory, and though not epoch-making, they are such as will render the name of Buffon memorable for all time.”