SUPPLEMENT I 



Part of a Letter (1867) 

 from Gregor Mendel to C. Nageli 



Translated from German by Leonie Kellen Piter- 

 nick and George Piternick. Reprinted from The 

 Birth of Genetics, Supplement to Genetics, Vol. 35, 

 No. 5, Part 2 (1950), by permission of Genetics. 



Gregor Mendel (1822-1884) 



SUPPLEMENT II 



Nobel Prize Lecture (1934) 

 of Thomas Hunt Morgan 



Reprinted by permission of The Nobel Foundation 

 for Les Prix Nobel. The complete lecture is pub- 

 lished in The Scientific Monthly for July 1935. Only 

 the first portion is reprinted here. 



Thomas Hunt Morgan (1866-1945) 



By permission of The American Genetic Associa- 

 tion, The Journal of Heredity, frontispiece, Vol. 24, 



No. 416, 1933. 



