190 BREEDING CROP PLANTS 



pure race for the absence of these characters and a normal variety 

 all FI plants had normal leaves. In F 2 , ratios of 672 normal- 

 leaved plants to 221 liguleless were obtained. 



Chlorophyll Inheritance. Numerous abnormalities for chlo- 

 rophyll development have been observed in corn, many of which 

 behave as simple recessives giving a 3: 1 ratio in the F 2 of a cross 

 between the normal and abnormal form. 



Lindstrom (1918) has reviewed earlier investigations of 

 chlorophyll inheritance and has made a careful genetic study 

 of several different chlorophyll abnormalities. Three of these 

 white, virescent-white, and yellow appear in the seedling stage. 

 The white form is a true albino, apparently lacking chloroplasts. 

 The virescent-white appears white at first, but under favorable 

 conditions it gradually becomes a yellowish green color, especially 

 at the tips of the leaves. There is considerable variation in the 

 appearance of different seedlings of this type but genetically all 

 behave alike. The yellow type gives seedlings with a yellow 

 color. Both the white and the yellow seedlings die before 

 maturity. 



The normal green form behaves as an allelomorph to the various 

 seedling abnormalities and contains the three dominant genes, 

 W, V, and L. Counts of the number of normal green plants 

 and the three seedling types obtained from various heterozygous 

 plants are as follows: 



Green 1,513 White 555 



Green 4,297 Virescent-white 1,394 



Green 1,493 Yellow 532 



Virescent-whites which turned green on maturity were selfed 

 and produced a progeny consisting of 717 virescent-white seed- 

 lings and nine green. The latter were due probably to stray 

 pollen. 



From a study of interrelation of these various factors, Lind- 

 strom has concluded that the following phenotypic formulas ex- 

 plain the appearance of different sorts of seedlings; 



GREEN VIRESCENT-WHITE YELLOW WHITE 



LVW LvW IvW LVw 



IVW Lvw 



IVw 

 Ivw 



These studies have considerable bearing on the present 



