AMERICA'S CHIEF CROP 333 



for thorns. But this can be shown only when the 

 seeds have been planted and have germinated. 



In the case of the corn, on the other hand, the 

 qualities of the individual kernels are revealed 

 in the outward appearance of the kernels them- 

 selves. The kernel that bears the factors for yel- 

 lowness will be yellow ; the kernel that bears the 

 factor for starchiness will be plump, hard, and 

 rounded ; and the kernel that bears the factor for 

 sweetness will be wrinkled because of its sugary 

 content. 



So a glance at the crossbred ear of corn re- 

 veals at once the story of its ancestry. 



So striking is the illustration of Mendelian 

 heredity when yellow field corn and white sweet 

 corn are crossed as in these early experiments, 

 that recent tests, in which actual count of the 

 different types of kernels has been made, have 

 shown results of mathematical exactness. 



Thus in an experiment recorded by Mr. R. H. 

 Lock, of Cambridge University, in which a 

 smooth yellow type of corn was crossed with a 

 wrinkled white variety, the grains of different 

 colors obtained from a certain number of ears 

 borne by the plants of the second generation 

 were distributed almost as evenly as if the work 

 had been done by hand by a careful human 

 calculator. 



