juiY 1911.] kuwada^maIo^Ik^in the p. m. a '■ of zea ma ys l. 117,7 



found; but the data secured at |)resent i^re not suffidfent yet 

 io conclude anything other than, stated before in this^^ respect 

 with certainty. ■ ' -' -^ 



Snmmary. 



The gemini in Zea Mays vary in number from 9, to 12. 

 Even in one and the same race there are certain variations. 



The sugar corns have generally a larger number and the 

 starch corns smaller ; and there seem to exist certain con- 

 nections between those two kinds of numbers of gemini, and 

 it is likely that the smaller numbers were reduced from 12 and 

 consequently the number 12 is original for all the races of 

 Zea Mays. 



The size and shape of gemini are tolerably different as 

 shown in the side view of the metaphase, and there are two 

 sets of them, that is, each sort of gemini is duplicated. In 

 the equatorial plate of the homotype division some pairs of 

 chromosomes come in contact with each other or even fuse up 

 altogether. 



Those two facts, chiefly the former, lead to the view that 

 Zea Mays is probably a tetraploidal plant, not necessarily 

 apogamic. 



It is suggested that the production of innumerable races of 

 Zea Mays has a certain relation with the duplication of 

 chromosomes, resulting in the double number derived from an 

 original form which had probably 6 chromosomes in reduced 

 number. 



An abnormal case was found in a race ' Amber rice pop 

 corn.' The geminial chromosomes, though not all, separate 

 from each other without intervention of the traction fibres, and 

 the individual separated member divides again transversely. 

 The homotj^pe division is mostly skipped and the resting 

 nuclei are directly formed. Sometimes few chromosomes are 

 left in cytoplasm and dwarf nuclei are formed. 



