INHERITANCE— IMPROVEMENT BY BREEDING 149 



there was a certain loss of grain from a few ears. This was 

 greater in some breeds than in others. In all cases, however, 

 care was taken to select the least broken ears for weighing, 

 and in many cases there was no loss from those that were 

 weighed ; at most it would not exceed half an ounce of 

 grain, which would not alter the percentage of grain to ear by 

 more than about '67 per cent. Making due allowance for this, 

 the percentages are considerably below those which American 

 growers consider fair (IF 88, p. 1 17). 



106. Effect of Depth of Grain on Yield. — One of the prin- 

 cipal factors, and perhaps the most important, in the production 



CHAP. 

 V. 



Fig. 64. — Increasing yield by increasing depth of grain (in Arcadia Sugar- 

 maize). A, old type ; B, improved type. 



of heavy yields of grain, is the depth of the grain (cf. Fig. 64). 

 Even an eighth of an inch added to the diameter of an ear, 

 when the cob remains of the same thickness, makes a marked 

 difference in the amount of grain carried on that ear. 



In seed selection, therefore, this character is of great im- 

 portance. To measure the relative depth of grain of each ear, 

 when handling several thousand ears, is a most tedious process, 

 and if some readily detected character can be found which is 

 correlated with depth of grain, it will be a useful guide. One 

 of the results of the writer's recent investigations has been the 



