406 SOME GREAT NAMES IN BIOLOGY 



many of his critics turn about and come over to his beliefs. He 

 died on the 19th of April, 1882, at seventy-four years of age. 



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 impor- 

 tance because the breeder is able to separate the qualities he desires 

 and breed for those qualities only. Another name we have men- 

 tioned 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. 



Gallon, Hereditary Genius. London (1892). 



Thompson, Heredity. John Murray, London England. 



Wasmann, Problem of Evolution. Kegan Paul, Trench, Triibner and Co., London, E. C. 



