128 EDGAR ANDERSON AND WILLIAM L. BROWN 



The Southern Dents (Brown and Anderson, 1948) are much more vari- 

 able. For over a century their variability has been stressed by all those who 

 have discussed them. The samples which we obtained from the South differed 

 from field to field, and from variety to variety. For an accurate understanding 

 of them and their history, we would like many more archaeological specimens 

 than we have for the flints, and many more colonial descriptions. Instead, we 

 have as yet no archaeological record, merely two accounts in early colonial 

 times — one from Louisiana and the other from Virginia. There is one passing 

 mention in a pre-revolutionary diary, and then a truly remarkable discussion 

 by Lorain in 1825. Finally, the United States Patent Office report for 1850 

 gives us, for region after region, a detailed picture of the extent to which this 

 purposeful mixing had proceeded by that time. 



To summarize the historical evidence, the Northern Flints were once the 

 prevailing type of maize throughout the eastern United States (Brown and 

 Anderson, 1947) with an archaeological record going back at least to a.d. 

 1000. There is as yet no archaeological evidence for their having been pre- 

 ceded in most of that area by any other type of maize, or of Mexican-like 

 dents having been used there in pre-Columbian times. The Northern Flints 

 belong to a type of maize rare or unknown over most of Mexico, but common 

 in the highlands of Guatemala. The Southern Dents, on the contrary, obvi- 

 ously are largely derived from Mexican sources, and by 1700 were being 

 grown as far north as Louisiana and Virginia (Brown and Anderson, 1948). 

 As to how and when they spread north from Mexico, we have no evidence 

 other than the negative fact that they are not known archaeologically from 

 the eastern United States, and are not represented in the collections of early 

 Indian varieties from that region. 



As early as 1800, the benefits of crossbreeding these two different types of 

 maize were appreciated by at least a few experts. By 1850 the process was 

 actively under way from Pennsylvania to Iowa, and south to the Gulf states. 

 By the '70's and '80's, a new type of corn had emerged from this blending, 

 although crossing and re-crossing of various strains continued up to the ad- 

 vent of hybrid corn. During the latter half of the process, the origin of Corn 

 Belt dents from 50 to 100 generations of selective breeding of crosses of 

 Northern Flints and Southern Dents was almost completely forgotten. Hav- 

 ing at length resurrected the evidence (Anderson and Brown, 1950) for this 

 mingling of two fundamentally different types of maize, we shall now turn 

 to the genetical and cytological evidence which first called the phenomenon 

 to our attention and led us to search for historical proof. 



CYTOLOGY 



The most important cytological contribution on the origin of Corn Belt 

 maize is found in a comparison of the numbers and distribution of chromo- 

 some knobs in the Northeastern Flints, open-pollinated varieties of Southern 



