PLANT HYBRIDIZATION BEFORE MENDEL 145 



was simply a question of filtering out the progeny until they be- 

 come true, either rose or blue-flowered. He remarks upon the fact 

 that "the color blue persists more obstinately, becomes fixed more 

 quickly, and once fixed maintains itself better, than the rose 

 color." (7b, p. 8.) 



Plate XXVIII. Louis Leveque de Vilmorin, 1816-1860. 



