230 MULTIPLE FACTORS 
Two varieties of tobacco, Nicotiana alata grandi- 
flora and N. forgetiana, were crossed by East. They 
differ mainly in the size and color of the flower. The 
corolla is three times as long in one as in the other 
variety, aS seen in Fig. 55. In the table, page 
185, the lengths of the corolla in the two varieties, 
_ Fie. 55.—At the left a flower of Nicotiana alata grandiflora; at the 
ee a flower of N. forgetiana; in the middle the F; hybrid. (After 
ast.) 
in the F,, and in the F, plants are given. The table 
shows the small variability of the parents. The F, 
generation is intermediate in length and also shows 
little variability, while the F, generation gives no 
definite ratios but exhibits great variability (Fig. 56), 
and overlaps the two grandparental types, although 
only a few flowers in F, are identical in size with those 
of each of the two grandparental types. These 
results are those expected if the two parent varieties 
