jJULYira.! :KU\VADA.-3UmSIS IN THE P.M.G. OF ZEA 3IAYS L. 173 



■;,diYisioii. At the! nuclear plate the corresponding number df 

 chromosomes is -usually to be found in every race. There were 

 .found in 'Sugar corn 'and 'Early eight sugar corn! 12 

 chromosomes, and in 'White flint,' 'Golden broach field 

 corn,' 'Amber rice pop corn,' the red starch corn, and the 

 yellow starch corn respectively 10. But very often I have met 

 with the cases where the smaller number of chromosomes such 

 as 9, 8, or even 7 was counted. In those cases there are always 

 to be found some chromosomes which are extremely large. Such 

 large chromosomes are naturally to be looked upon as the 

 products of fusion of some chromosomes. In the equatorial 

 plate of ' White flint ' in which 10 chromosomes were found, 

 two of them come often close to each other (Figs. 29, 30), and 

 in certain cases such chromosomes were found entirely 

 fused up with each other, forming a giant chromosome, and 

 consequently there being but 9 chromosomes instead of 10 

 (Fig 31). Such fusion of chromosomes Soes not occur alike in 

 both sister cells ; the one may have 9 chromosomes, w^hile the 

 other 10 as in the normal case. This shows that the fusion of 

 chromosomes occurred after the heterotype division had passed 

 over. In other races in which this peculiar reduction of the 

 number of chromosome goes much further it was not ascer- 

 tained that the giant chromosomes were the products of the 

 fusion of 2 normal chromosomes ; but from the fact observed 

 in ' White flint ' we can infer that such reduction would have 

 probabl}^ taken place in the same manner. 



The paired arrangement of the homologous chromosomes 

 in the somatic diploid cells has been reported by many writers, 

 since Strasburger (7) noticed it at first. These pairs of 

 chromosomes are sometimes found fused up into one, and there 

 is observed only the haploid number of chromosomes. 

 Such a case is mentioned by Tischler in Musa (10). Such 

 fusion of the homologous chromosomes may not extend to all 

 the chromosomes, and some of the chromosomes may retain 

 their individuality. Similarly in my present case the giant 

 chromosomes are to be considered to have been formed by the 

 fusion of the two homologous chromosomes, while other homo- 



