INHERITANCE— IMPROVEMENT BY BREEDING 207 



made by East and Hayes and by the writer to study the in- CHAP, 

 heritance of the tendency have not been very successful. But 

 East and Hayes conclude that the character is transmitted 

 and does segregate, for both normals and abnormals are pro- 

 duced in the F 2 generation. Such ears are undesirable, 

 especially as they produce irregular grain, and they should not 

 be used for seed purposes. 



161. Striped Leaves. — 

 Races of maize occur, as, 

 for example, Zea Mays var. 

 japonica, in which the leaves 

 are green, with white stripes 

 (they are deficient in chloro- 

 phyll), but which breed true, 

 the striping being appar- 

 ently homozygous. 



But East and Hayes 

 record cases in which the 

 striping indicates a hetero- 

 zygous condition; the 

 dominant form in this case 

 is fully green. Plants with- 

 out chlorophyll died, when 

 only a few inches high, 

 from lack of the power of 

 assimilation ; these were 

 considered by the authors 

 as " probably homozygous 

 recessives ". 



162. Difficulties En- 

 countered in Studying In- 

 heritance in Maize. — The 

 investigation of the inheri- 

 tance of characters in the 



maize plant is not as simple a problem as might at first 

 appear. 



(a) The amount of pollen produced is so great that it is 

 continually present during the flowering period, in the air of 

 the maize field ; it adheres to the clothes and hands of the 

 breeder, or to the leaves and stems of the plant, and is easily 



Fig. 86.— Laterally branched ear. 



