Associated with Darwin's name we must place two other co-workers on heredity and evolution, Alfred Russel Wallace, an Englishman who independently and at about the same time reached many of the conclusions that Darwin came to, and August Weissman, a German. The latter showed that the protoplasm of the germ cells (eggs and sperms) is directly handed down from generation to generation, they being different from the other body cells from the very beginning. In 1883 a German named Boveri discovered that the chromosomes of the egg and the sperm cell were at the time of fertilization just half in number of the other cells (see page 252) so that a _fertilized_ egg was really a _whole cell_ made up of _two half cells_, one from each parent. The chromosomes within the nucleus, we remember, are believed to be the bearers of the hereditary qualities handed down from parent to child. This discovery shows us some of the mechanics of heredity. Applications to Plant and Animal Breeding.--Turning to the practical applications of the scientific work on the method of heredity, the name of Gregor Mendel, an Austrian monk, stands out most prominently. Mendel lived from 1822 until 1884. His work, of which we already have learned something (see page 258), remained undiscovered until a few years ago. The application of his methods to plant and animal raising are of the utmost importance because the breeder is able to separate the qualities he desires and breed for those qualities only. Another name we have mentioned with reference to plant breeding is Hugo de Vries, the Dutchman who recently showed that in some cases plants arise as new species by sudden and great variations known as _mutations_. And lastly, in our own California, Luther Burbank, by careful hybridizing, is making lasting fame with his new and useful hybrid plants. REFERENCES Conn, _Biology_. Silver, Burdett & Co. Darwin, _Life and Letters of Charles Darwin_. Appletons. Galton, _Hereditary Genius_. London (1892). Thompson, _Heredity_. John Murray, London England. Wasmann, _Problem of Evolution_. Kegan Paul, Trench, Truebner and Co., London, E. C. APPENDIX A SUGGESTED OUTLINE FOR BIOLOGY BEGINNING IN THE FALL LIST OF TOPICS FIRST TERM