GENERAL, CONSIDERATION OF ALT. THE TESTS, 



65 



crosses, and that further work witli all conditions more nearly equalized 

 will demonstrate a general tendency for first-generation crosses to pro- 

 duce better than the average of the parents. Such a general tendency 

 might be due to prepotency of the higher yielding parent. It is more 

 profitable to grow the higher yielding parent except in cases in which 

 the first-generation cross produces better than either parent. Since 

 some first-generation crosses are more productive and some are less 

 productive than their better parent, the greatest benefit can be 

 obtained by planting such as may be found more productive than 

 the highest yielding variety of a community. 



PERCENTAGE OF MOISTURE IN SHELLED GRAIN OF CROSSES AND 



PARENT VARIETIES. 



Because of care in allowing the ears of all varieties to dry thor- 

 oughly before yields were weighed it has not been necessary to calcu- 

 late corrections for moisture content except in the Maryland tests. 

 The moisture content of shelled grain from a large number of ears of 

 each variety at each point was determined by the Office of Grain Stand- 

 ardization of the Bureau of Plant Industry. Regarding this char- 

 acter, averages as given in Table XIX show the first-generation 

 crosses to be intermediate between the parents. 



Table XIX. — Average percentage of moisture in shelled grain of crosses and parent 

 varieties on dates when yields were weighed. 



Tests. 



Maryland 



California 



Texas 



Georgia 



General average 



Female 

 parents. 



27.29 

 10.22 

 12. 39 



15.40 



16.33 



Male 

 parents. 



28.77 

 11.74 

 11.45 

 15.01 



16.74 



Average 

 of both 

 parents. 



28.03 

 10.98 

 11.92 

 15.21 



16.54 



First-gen- 

 eration 

 crosses. 



28.32 

 10.90 

 12.13 

 15.00 



16.59 



UNRELIABILITY OF AVERAGES FOR SPECIFIC INSTANCES. 



With investigations of this nature the investigators as well as the 

 readers are desirous that the work should discover some law of nature. 

 However, the development and evolution of plants furnish so many 

 exceptions and variations to even general laws that it is impossible 

 to foretell the effects of crossbreeding particular varieties by the 

 effects secured previously from crossbreeding other varieties. T^-pes, 

 varieties, strains, ears, and even kernels of corn contain in their 

 lineage such complexit}^ of structure and characters that it is not 

 surprising that this work, necessarily of a prehminary nature, should 

 unfold more problems than it solves. 



The results are interesting because they contain evidence in sup- 

 port of various theories, but the chief value of the work is its indi- 



218 



