670 WHO ARE SOME OF THE MAKERS OF BIOLOGY? 



PROBLEM V. WHAT ARE SOME GREAT NAMES CONNECTED 

 WITH PLANT AND ANIMAL BREEDING? 



Weissman. August Weissman, a German, showed that the 

 protoplasm of the germ cells (eggs and sperms) is handed down 

 directly from generation to generation, these cells being different 



from the others in the body al- 

 most from the beginning of the 

 development of the embryo. 



Workers with Chromosomes. 

 In 1883 a German named 

 Boveri discovered that the 

 chromosomes of the egg cell 

 and of the sperm cell are at 

 the time of fertilization just 

 half the number of those of the 

 other cells (see page 627), so 

 that a fertilized egg is really a 

 whole cell made up of two half 

 cells, one from each parent. 

 The chromosomes, we remem- 

 ber, are known to be the 

 bearers of the hereditary quali- 

 ties handed down from parent to child. Some of the most impor- 

 tant work on the chromosomes has been done by Thomas Hunt 

 Morgan, who is now a professor at the California Institute of 

 Technology. He and his students have worked with a little fruit 

 fly, in the chromosomes of which have been isolated the tiny genes 

 which have been found to be the structures which pass on the 

 heredity qualities from parent to offspring. 



Mendel. 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 was born 

 in 1822. He early entered the monastery at Brunn, where he lived 

 until his death in 1884. In 1865, after several years of experimen- 

 tation, he published the results of his work on inheritance in peas. 

 But his work created no interest at the time and remained un- 

 known until the year 1900, when it became world-famous. The 



August Weissman. 



Culver Service 



