One distinction too often overlooked by those who are not familiar with physiological science is the difference between actual physical inheritance and external customs. I wish to dwell at length upon this distinction, because a lack of understanding upon this point has been the source of many errors of judgment on the part of those who have been interested in the subject of physical training and food science. At birth the individual inherits an organism with certain tendencies, both physical and mental, but this inheritance should not be confused with the physical habits which the child acquires by training from its parents and its associates. Thus, the child may inherit a brilliant mind, a weak stomach, or a sixth finger, but the child does not inherit a liking for broiled lobster, or a fondness for golf, or for driving an aeroplane. These are acquired and developed as habits, the same as the child would learn English or French, or would cultivate a fancy for parting his hair in the middle, or on the left side. THE THREE GREAT PROOFS OF THE EVOLUTION OF ANIMAL LIFE At the present time scientists are agreed upon the general theory of the evolution of man. The discussions pro and con regarding this, which exist today, are either discussions of minor points which have not yet been clearly worked out, or are the discussions of people who have grasped only a portion of the idea of evolution, and who are ignorant of its broader conception and of the facts which science has brought to the light of day. The three great proofs of evolution are: 1 The actual history of the past recorded as fossils in the rocks and in the relics of pre-historic races 2 The existence in the world today of a range of animals and plants which shows living examples of earlier types 3 The repetition of the development of man as found in the growth of the individual These three separate records of the development of living beings are considered by scientists as a most conclusive proof of the truth of evolution. Recorded as fossils in the rocks, we find the story of the development of all life upon the earth, from its simplest to its highest forms of plants and animals that live today, among which is man. [Sidenote: The earliest forms of animal life] The first forms of animal life were, in all probability, minute one-celled organisms; these left no visible fossil remains. As soon as animals developed hard parts in their bodies, such as shells and bones, we find a record of their existence as fossils. The earliest recorded forms of life were various kinds of sea-creatures, of which the modern crustacea (lobsters, etc.), snails, clams, and various shell-fishes are types. Later were developed boneless fishes, on the order of skates. After these came true fishes; then amphibia (frogs, etc.); then reptiles, birds, and, last of all, mammals, including man.