156 THE THEORY OF THE GENE 



each pole, while the 7 singles are distributed at random — 

 more often 3 going to one pole and 4 to the other. Accord- 

 ing to Sax, the 7 single as well as the 14 reduced chro- 

 mosomes split at the second division. 



Whichever interpretation holds for the single chromo- 

 somes (and there are in other forms precedents for either 

 interpretation), one important fact is evident, viz., that 

 conjugation takes place only between 14 chromosomes. 

 Whether this union is between the 14 chromosomes de- 

 rived from the Emmer and 14 chromosomes derived from 

 the Vulgare, or whether the 14 chromosomes of the Emmer 

 unite to make 7 conjugants and 14 of the Vulgare unite to 

 make 7 conjugants, leaving one set of 7 over, is not clear 

 from the cytological evidence. A genetic study of these or 

 similar combinations (this one gives a sterile hybrid) 

 may furnish decisive evidence, but this is lacking at 

 present. 



Kihara also crossed Einkorn, having 14 chromosomes 

 (n=7), with Emmer wheat, having 28 chromosomes (n= 

 14). The hybrid, having 21 chromosomes, is a triploid. 

 In the maturation of the germ-cells of the hybrid (pollen 

 mother cells) there is much more irregularity than in the 

 last case (Fig. 90e-k). The number of the conjugating 

 chromosomes is variable and their union, when it occurs, 

 is less complete. The number of the gemini varies as 

 shown in the next table. 



At the first division the components of the gemini sepa- 

 rate and pass to the poles. The splitting of the single 

 chromosomes does not alwavs take place before thev have 



