354 



Thk Jourx.\l of Herkdity 



DOWN OF LVON BEAN 



The fresh down from a nearly full-grown pod 

 of Lyon bean, mounted in water. A 

 short basal cell in most cases accom- 

 panies the unicellular hair. Scale in 

 tenths of a millimeter. (Fig. 12.) 



had black tomentum mixed with the 

 white pubescence on their young shoots. 

 The color varied from grayish brown to 

 brownish-black. 



The black plants with long tomentum 

 (long black) had sometimes tomentum 

 on their pods almost as rough as that of 

 the Velvet bean, but it was usually softer 

 and blacker. It was sometimes sparse. 



The black plants with short tomentum 

 (smooth black) usually lost most of it 

 from their ripe pods, so that they appeared 

 glabrous and coal-black. In a few cases 

 the tomentum was lighter brown. 



Since more than half of the black 

 plants set no pods, the ratio of long 

 black to smooth black cannot be deter- 

 mined. Rather more than three times 

 as many long l^lack plants set pods in 

 the three crosses, but the smooth black 

 were distinctly later and more abnormal. 

 Hence it is possible that the ratio is 2 :1. 

 The segregation appears in Table A. 



In the first cross so many plants with 

 white pubescence set no pods that the 

 proportions are rendered unreliable. 

 From the close agreement of the other 

 two crosses with the calculated most 

 probable numbers, wc may be sure that 

 the proportions are : 



Stinging. Downy. 

 9 : 3 



"Velvet." Black. 

 1 : 3 



Table A 



that the intermediate formed only about 

 one-twelfth of the whole number of 

 downy ])lants. A minority of downy 

 pods had more or less erect hairs, and a 

 few had sparse down. The hairs were 

 either yellowish or white. 



The "Velvet" plants had sometimes 

 stiller tomentum than that of the Velvet 

 bean, and more straight hairs. Some 



THE THIRD GENER.\TION. 



STINGING PLANTS.— Thirty-six 

 stitiging i)lants, from the second genera- 

 tion of the Velvet- Lyon cross, had the 

 majority of their surviving progeny in 

 each family stinging, when their seeds 

 were grown among crowded sorghtim in 

 ail elimination test (see Kept, of the Fla. 

 Agr. Exp. Sta. for 1912, pp. 115-127). 



