26 



CIRCULAR NO. 120, BUREAU OF PLANT INDUSTRY. 



be e.xpoctcd. hut ;m examiiiatioii of the separate families indicates 

 that this aijreeiiient is accidental, for of the four families one is above 

 the expected innnber l)y nearly five times the |)robable error and two 

 are below by more than three times the probable error. 



Tablk II. — Proportiiin of xirccf. ini.iii. niiil lioniji ncctls of iiKiiic coDiiinrrd irith 



the (•■iiKctcd ratios. 



CONCLUSIONS. 



The general classification of maize varieties is based on the char- 

 acters of the seed. Varieties with horny, soft, and sweet endosperm 

 have been recognized since early colonial times, and these three types 

 represent the only forms in which the endosperm of maize was 

 known to exist until the di.scovery of w^axy endosperm in a variety 

 of maize introduced from China in 1908. Investigations of the 

 heredity of this new type of endosperm show^ that Avhen the Chinese 

 variety is crossed with sweet varieties seeds are produced which, 

 unlike either parent, have a horny endo.sperm. Although this 

 synthetic horny endosperm is indistinguishable from that of ordinary 

 field varieties, it behaves in an entirely different manner in the 

 following generation. 



All of the plants grown from these hybrid seeds produced ears 

 with horny, sweet, and waxy .seeds. The jn'oportion in which the 

 three classes occurred approximated nine horny, four sweet, and 

 three waxy, a ratio indicating that the sweet and waxy characters 

 are the result of independent factors and that one out of every four 

 sweet seeds, though indi.stingui.shal)le from oi'dinary sweet seeds in 

 the first generation, represents a new type of sweet corn. Experi- 



ICir. 120 J 



