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SOME LATENT CHARACTERS OF A WHITE BEAN 1 



IN order to secure material to display as 

 simple illustrations of Mendel's laws of domi- 

 nance and gametic purity, I made reciprocal 

 crosses last year (1904) among four different 

 varieties of the common bush bean. These 

 varieties were the ' Prolific black wax/ with 

 purple-black seeds, the *Ne plus ultra' with 

 yellow-brown seeds, the ' Long yellow six- 

 weeks ' with seeds of a light greenish-yellow 

 color, and the ' White flageolet,' whose seed- 

 coats are wholly without pigment, being trans- 

 parent when saturated with liquids, but nearly 

 white because of the inclusion of air when 

 dry. 



I have this year (1905) the first generation 

 of the hybrids, and all the crosses behaved in 

 the expected way except those in which the 

 'White flageolet' entered as one of the par- 

 ents. The crosses between black and brown, 

 black and yellow, and between brown and 

 yellow showed in every case the complete 

 dominance of the darker pigment over the 

 lighter. Thus, the first-generation hybrids be- 

 tween black and brown beans and those be- 

 tween black and yellow were in every case 

 indistinguishable in color from the black 

 parent, whether the black bean supplied the 

 egg or the sperm. Similarly the hybrids 

 between the brown and yellow were in each 

 case not to be distinguished from the brown 

 parent. But the crosses between each of these 

 three pigmented varieties and the 'White 

 flageolet' gave F l hybrids so different from 

 either parent that, if unknown, their origin 

 would never be guessed. These seemingly 

 anomalous hybrids were quite indistinguish- 

 able from one another, whether the pigmented 

 parent was black, brown, or yellow. They 

 were characterized by a dark purple pigment, 

 and by an aggregation of the pigment-bearing 



1 E,ead before the Botanical Society of America, 

 at New Orleans, December, 1905. 



