CLIMATIC REQUIREMENTS 4S 



in the Southern States dents are grown almost exclusively, chap. 

 Dents generally yield more heavily than flints, but take longer IL 

 to mature; flints mature earlier, but as the yield is lighter 

 they are grown only where others cannot mature owing to 

 shortness of season. 



It is said that a northern flint variety, after having been 

 grown for several years in Illinois, changed under the influence 

 of climate into a dent ; but before concluding that this change 

 was caused by change of climate it should be known whether 

 any precautions had been taken against cross-pollination, for 

 if crossing had taken place between the flint and a dent, the 

 heterozygous grains might retain the flint appearance and 

 would later produce dent grains, which, if selfed, would breed 

 true. 



Sugar maize is said to be rarely grown in the Southern 

 States, but whether this is due to the climatic conditions being 

 unfavourable for the production of sugar maize, or whether it 

 may be due to the taste of the people, is not clear. 



34. Influence of Climate upon Chemical Composition. — As 

 the result of thirty-five analyses of dent maize grown in the 

 Northern States, and forty-nine from the Southern, Hunt (1) 

 concludes that there is no material difference in composition 

 in maize grown in different parts of the country,, over a very 

 wide range of soils and climates. Analyses of Transvaal 

 samples made by the Division of Chemistry of the Union 

 Department of Agriculture tend to confirm this view (see 

 chap. xill.). 



