330 THE SURVIVAL OF THE UNLIKE. [xiX. 



Lake district northwest of Lake Superior."* This 

 wonderful change in the habit of maize has been 

 brought about solely through the agency of man. 

 "Hence it has been found possible, according to Kalra, 

 to cultivate maize further and further northward in 

 America. In Europe, also, as we learn from the evi- 

 dence given by Alph. De CandoUe, the culture of 

 maize has extended, since the end of the last (ientury, 

 thirty leagues north of its former boundary, "t The 

 earlier corns, that is, those which require a shorter 

 period of growth, are usually the so-called flint corns, 

 while the later or southern corns are usually dents. 

 Dr. W. J. Beall found that flint corn becomes well 

 marked with dent in three years when taken from 

 Michigan to Kansas. On the contrary, "at Lansing, 

 Mich., dent corn has a tendency to ripen earlier and 

 become round at the tip of the kernel from year to 

 year, unless care is taken by selecting seed which shows 

 prominent dents in the ends of the kernels. In 

 southern Ohio and Indiana there is not that tendency 

 for dent corn to change to flint corn." Those who 

 deny the occurrence of acclimatization cite the fact 

 that Indian corn is no more able to resist frost now 

 than when first known to the white man. This state- 

 ment is probably true, yet of all plants corn is one of 

 the most ready to adapt itself to climate by way of 

 shortening its period of growth. It habituates itself 

 to a climate at first injurious to it. For instance, the 

 first crop of dent corn grown in Michigan from south- 

 ern seed will be very poor, most of it being cut by 

 the frost. Successive sowings from the same stock 



•James S. Lippincott, U. S. Agr. Rep. 186.3, 512. 



tDarwin, Animals and Plants under Domestication, ii. 370 Amer. Ed. 



tMich. Agr. Rep. 1880, 283. 



