JULY 1911.1 KUlVADA.—MArOSIS TX THE P.M.C. OF ZEA MAYS L. 175 



one hand that the number of chromosomes can be equal among 

 the different species which are not closely related, and on the 

 other hand that they can be quite different, as recent investiga- 

 tions have shown, in species very closely allied, and occasional- 

 ly even in one and the same plant, neither the difference nor 

 equality of the number of chromosomes alone can serve as the 

 strong criterion for such a question especially when ^ve are 

 dealing with extremely polymorphic types of plants as those of 

 Zea. In case the plants are so closely related to each other 

 that they are easily taken for varieties or forms of a certain 

 species and at the same time present features regarding the 

 numbers of chromosomes indicating that they were derived 

 from a certain orginal number, however, we are probably justi- 

 fied to consider those plants as having descended from a 

 certain original species. 



Of the three races of the sugar corns I have investigated, 

 only the red sugar corn has the less number of gemini 

 than the other two, and the}^ are generally 10 in number. But 

 at the segmentation it was observed that there was an in- 

 dication of as many gemini as those of the other two, i.e. 

 12. Besides it was found that the general number 10 is often, 

 reduced into 9. In ' Early eight sugar corn ' I have also met 

 with a case in which only 9 gemini came in view. From 

 these facts I am inclined to believe that the decrease in number 

 of gemini in the red sugar corn is due to a secondary 

 process," and all the sugar corns have once carried 12 gemini 

 in the development history of the race. And the fact 

 that the number of gemini in certain sugar corn is often 

 reduced to 10 or even 9 leads us to the idea that the starch 

 corns, those having 10 or 9 gemini, once carried 12 gemini 



* The exact nature of the process is here unknown. Strasburger (8, P. 406) 

 has expressed a view on the variation of the number of chromosomes in the case of 

 the polyploid plants: " 1st jede Erbeinheit und jede Chromosomenart mehrfach im> 

 Kera vertreten, so mogen diese Wiederholuugen. Bedingungen schafFen, die zu einer 

 Verminderung der iiberzahligen Chromosomen fiihren." The investigation of the 

 hybrid between the races^ haying 10 and. 12 gemini would throw some light on that 

 point. 



