Nov. ij. I93I Genetic Behavior of Spelt Form in Crosses 



347 



3. The spelt might have carried a spelt factor Sj and in addition 

 another factor 83, which would produce the spelt character if there were 

 present its complementary factor C, which might have been supplied by 

 the wheat parent. In this case if C were present the ratio would be 

 about 8 spelts to i wheat; and if C were not present, it would be 3 to i. 

 The ratios to be expected on the basis of this last possibility, however, 

 are not in accord with the experimental results. 



The second explanation seems to be the most plausible of the three. 

 The assumption that some wheats carry the factor for the inhibition of 

 the spelt character is not a mere speculation but a fact, as will be seen 

 later when the question of the production of synthetic spelts by crossing 

 two wheats is taken up. As commercial strains of T. sativum are not 

 purified with respect to inhibitors, there are undoubtedly some strains 

 which contain individuals heterozygous for this factor. If such a plant 

 is used, for instance, as the female parent and is crossed with a spelt 

 carrying the factor for spelting, according to the hypothesis some of the 

 seeds will produce Fj progeny where in some instances the ratio will sug- 

 gest a 15 to I, and in others a 3 to i segregation. As will be seen later, 

 other modifications of these ratios may also be expected to arise. 



PROGENY OF STABILIZED SPELTOID X SATIVUM CROSSES 



The speltoid form used in the crosses which will be considered now 

 is commercially known as "Gatineau." The variety originated from a 

 cross between T. durum and T. sativum. It grades usually from 4 to 7 

 in the classification used in this study for spike form and so resembles 

 the commercial spelts in this respect. It does not have the brittle rachis 

 of spelt, and the grain thrashes from the glumes more easily than the 

 grain of spelt, being like some of the tight-glumed wheats. It is neither 

 a typical spelta nor a typical sativum. 



The F^ plants of the crosses between Gatineau and T. sativum were 

 almost like Gatineau. The Fj generation consisted of forms which were 

 intermediate; typical spelts of classes i to 2 were not found. The classi- 

 fication of the Fj individuals is reproduced in Table VII. 



Table VII. — Classes of F2 generation plants of two speltoid X wlieat crosses. Numbers 

 of individuals obtained compared with the theoretical expectations 



> Series 13228a Turkey (C. I. 3375. Sel. 13389) X Gatineau (C. I. 2959. Sel. 13403). 

 'Series 13339a Seneca Chief (C. I. 3372, Sel. 1338S) XGatineau(C. I. 3959, Sel. 13403). 



