THE WHITE BLACKBERRY 



A very simple and tangible illustration of the 

 phenomena in question is furnished by the experi- 

 ments in animal breeding made by Professor 

 William E. Castle of Harvard. These experiments 

 furnish a peculiarly appropriate illustration in the 

 present connection because it chances that the 

 animals experimented with are comparable to our 

 blackberries in that they are respectively black 

 and white in color. 



The animals used in the experiment are guinea 

 pigs. 



An Illustration From the Animal World 



Professor Castle shows that if a black guinea 

 pig of a pure strain is mated with a white guinea 

 pig of a pure strain, all the offspring of the first 

 generation wdll be black; and it is therefore said 

 that blackness is prepotent or dominant, and 

 whiteness recessive. But if two of these black off- 

 spring are interbred, it is an observed fact that 

 among their progeny three out of four individuals 

 will be black like their parents and one of their 

 grandparents, and the fourth one will be white 

 like the other grandparent. 



The Mendelian explains that the factor of 

 whiteness was submerged, dominated by the 

 factor of blackness, in the second generation; but 

 that half the germ cells of these black individuals 

 contained the factor of whiteness, and that by the 



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