The doctrine of evolution enjoins us to learn the rules of the great game of life which we must play, as science reveals them to us. It is well to remember that a little knowledge is a dangerous thing, but because evolution is true always and everywhere, an understanding of its workings in any department of thought and life clears the vision of other realms of knowledge and action. Perhaps the greatest lesson is at the same time the most practical one. It is that, however much we may concern ourselves with ultimate matters, our immediate duties are here and now, and we cannot escape them without giving up our right to a place in nature. We are taught by science that we live under the control of certain fundamental biological, social, and ethical laws; we might well wish that they were otherwise, but having recognized them we have no recourse save to obey them. Evolution as a complete doctrine commands every one to live a life of service as full as hereditary endowments and surrounding circumstances will permit. Thus we are taught that the immediate problems of life ought to concern us more than questions as to the ultimate nature of the universe and of existence. Every one can find something worth while in the lessons of evolution, summarized in the foregoing statements. The atheist, who declines to personify the ultimate powers of the universe, may, nevertheless, find direction for his life in the principles brought to light by science. The agnostic, who doubts the validity of many conventional dicta that may not seem well grounded, can also find something to believe and to obey. Finally, the orthodox theist of whatever creed may discover cogent reasons for many of his beliefs like the Golden Rule previously accepted through convention; and he must surely welcome the fuller knowledge of their sound basis in the materials and results of comparative analytical study. To every one, then, science and evolution offer valuable principles of life, but great as their service has been, their tasks are not yet completed, and cannot be completed until the end of all knowledge and of time. INDEX Achatinellidae, 103, 104. Activities, instinctive and reflex, 203, 205, 208; of familiar animals, 208, 209; differ from instinct, 209, 210. Adaptation, universal relation to environment, 15; principle of, 17; degenerate forms enlarge our conception of, 50; results of larval short cuts in development, 71; 109, 213. Africa, fauna of, 103, 164, 165. Agassiz, a believer in special creation, 98. Ages, Palaeozoic, 92; Mesozoic or Secondary, 93, 94; Cenozoic or Tertiary, 93; Coal or Carboniferous, 94. Albumen, of egg, 60. Alligators, a diverging branch of lizard, 45. Amoeba, 21, 51, 69; comparative study of, 203, 205, 231, 247, 251, 254, 257, 258, 259, 265, 266.