232 



THE AMERICAN XATURALIST [Vol. LIIl 



moth character in the progeny of a normal phmt. It may 

 be stated here that East (1917) has offered the same sug- 

 gestion concerning the origin of variations in cell-divi- 

 sions preceding the formation of the gametes themselves. 



The Peoductiox of Xew Mammoth Foems by 



HYBEmiZATION 



Two Mammoth types of tobacco are now grown com- 

 mercially in the United States, the Maryland Xarrowleaf 

 Mammoth in Maryland, and to a lesser extent the Stew- 

 art Cuban in the Connecticut Valley. Promising Mam- 

 moth types have also originated in Havana Seed tobacco 

 in Connecticut. Beinhart (1918, however, in a brief dis- 

 cussion of the occurrence of Mammoth types in the Con- 

 necticut Valley, states that practical methods of seed pro- 

 duction and special cultural methods must be worked out 

 before the Stewart Cuban Mammoth and the Havana Seed 

 ]\ramraoth can be successfully grown on a commercial 

 -cile. Although these Mammoths originated spontane- 

 ously from commercial types, there is every reason to 

 believe that valuable new types can be secured by cross- 

 ing with the ordinary commercial types of tobacco. 

 Since in crosses with ordinary varieties gigantism is re- 

 cessive in its inheritance, the problem of producing new 

 giant tA'pes by hybridization and recombination has not 

 been difficult. Several :\laininotli types have already 

 been secured in crosses with Comioctient Broadleaf, Little 

 Dutch and White Burley. If by this means it is possible 

 to combine the habit of gigantism, which insures greatly 

 increased yields, with the desirable quality characteris- 

 tics of ordinary varieties, very valuable commercial types 

 can be obtained. 



1. Gigantism has occurr(Ml in -cvrr.il dilTenmt commer- 

 cial varieties of tobacco, inchiding ^Sfaryland types, Cu- 

 ban, Connecticut Havana and Sumatra. It has also been 

 associated with certain varietal crosses and species 



