No. 511] SELECTION INDEX NUMBERS 



399 



Length 



Weight of shelled corn 

 Weight of corn shelled 

 Weight of cob 



14.8 cm. 



12.9 " 

 118.0 gr. 



9.3 " 



Butt circumference . . 

 Tip circumference . . . 



16 



33 



100 per 



Using these data to calculate the selection index it ap- 

 pears that : 



The value of the index in this case is much above the 

 average for the particular variety of sweet corn of which 

 this ear is a representative. This is, of course, as it 

 should be, since the ear is a particularly fine one for 

 sweet corn. Its aristocratic lineage is apparent from the 

 photograph. Some ears of this variety give a value for 

 the index of as low as 1.0 or even lower. It is obvious 

 that the index number for an ear of one variety is not 

 directly comparable with that for an ear from another 



Whence we ha 



