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THE AMERICAN NATURALIST [Vol. XLVIII 



DUPLICATE GENES 

 Some interesting questions are raised by a recent, article by 

 Gregory: "On the Genetics of Tetraploid Plants in Primula 

 sinensis." 1 Reciprocal crosses of two races of P. sinensis were 

 made. One cross gave entirely normal results in F 2 as regards 

 chromosome number and hereditary characters. The reciprocal 

 cross gaye an F, generation which was sterile with the parents 

 and produced only a giant variety in F 2 . This proved to have 

 the tetraploid chromosome number. Experiments indicated that 

 the genetic factors had also all been doubled, a very significant 



P Gregory uses the nomenclature A AAA, AAAa, AAaa, Aaaa, 

 and aaaa to represent all the possible conditions as regards a 

 pair of Mendelian factors. He states that heterozygotes of the 



