1920] 



KA N DA— VERBENA 



67 



late. It is safe to conclude, however, that 12 is also the 2X number 

 for this species, since in the early telophase of the first division 

 (fig- 75) 6 chromosomes are clearly present at each pole of the 

 spindle. I have further often counted 12 chromosomes in all of 

 the forms except V. angustifolia in the anaphase stage in young 

 locular cells of anthers, and 18 chromosomes, the $x number, in 

 the endosperm cells. The behavior of the chromosomes of the 

 intermediate form in mitosis is entirely normal, and like that of the 

 original species. No such abnormalities as were described by 

 Rosenberg (16) in Drosera hybrids can be recognized. 



Owing therefore to the unfortunate fact, which could not be 

 foreseen, that both of the original species selected for comparison 

 with a form intermediate between them have the same number of 



69 



70 



71 



72 



73 



74 



75 



Figs. 69-75. — Mitosis of pollen mother cell: figs. 69, 70, V. angustifolia; figs. 71, 

 72, V. stricta; figs. 73, 74, intermediate form between V. stricta and V. hastata; fig. 75, 

 V. hastata; X1500. 





chromosomes, cytological observations upon them do not serve 

 to settle the question as to whether the intermediate form is a 

 hybrid or not. It is clear that the intermediate form does not 

 differ cytologically from the original forms, and that its mitotic 

 behavior is entirely normal. These facts, if they have any sig- 

 nificance at all, tend to suggest that the intermediate is not a hybrid, 

 but rather a mutant of one or the other of the original species. 

 This could be determined only by breeding it through several 

 generations and observing whether its characters are fixed or not. 

 Cytological studies of the forms intermediate between 

 V. angustifolia and the other two species might have yielded more 

 definite results, because it differs from them in the number of its 







chromosomes. Unfortunately I did not collect any material from 

 these forms, as they are relatively rare. 



