that are less highly specialized, and hence are adaptable to new conditions. Under new conditions the main stem of development perishes and the budded branch survives. We have abundant pictures of this in prehistoric times, and records show that this also has been the common lot of man. Modern man thus could not have been developed from any of the living species of the Anthropoid Apes, but he might have had a common origin in the physical, chemical, and vital forces that produced the apes. One line of specialization made the ape, another line made man. Subsequently the separation of man into the various races and species came about by the survival of some races for a time, and then to be superseded by a branch of the same race which differentiated in a period of development before high specialization had taken place. _Methods of Recounting Prehistoric Time_.[1]--Present time is measured in terms of centuries, years, months, weeks, days, hours, minutes, and seconds, but the second is the determining power of mechanical measurement, though it is derived mainly by the movement of the earth around the sun and the turning of the earth on its axis. Mechanically we have derived the second as the unit. It is easy for us to think in hours or days or weeks, though it may be the seconds tick off unnoticed {59} and the years glide by unnoticed; but it is difficult to think in centuries--more difficult in millions of years. The little time that man has been on earth compared with the creation of the earth makes it difficult for us to estimate the time of creation. The much less time in the historical period makes it seem but a flash in the movement of the creation. ====================================================================== TWENTY-FOUR-HOUR DIAL ILLUSTRATING HUMAN CHRONOLOGY[2] Twenty-five thousand years equals one hour [Illustration: Twenty-four hour dial] Age of modern man 10,000 years = less than half an hour. Age of Cro-Magnon type 25,000 years = one hour. Age of Neanderthal type 50,000 years = two hours. Age of Piltdown type 150,000 years = six hours. Age of Heidelberg type 375,000 years = fifteen hours. Age of Pithecanthropus 500,000 years = twenty hours. Beginning of Christian era 2,000 years = 4.8 minutes. Discovery of America 431 years = about 1 minute. Declaration of Independence 137 years = about 21 seconds. ======================================================================