[JANUARY 



BOTANICAL GAZETTE 



66 



At the time of the first mitosis of the microspore mother cell 

 the flower buds of the 4 forms are in different stages of development. 

 As shown in figs. 60-63, the buds of V. angustijolia and V. hastata 

 are in a relatively young stage when this event occurs, those of 

 V. stricta in a much later stage, and the intermediate form at a 

 stage between these two. In respect to this character, then, the 

 latter occupies an intermediate position. 



As described in a preceding section, tetrad formation occurs in 

 V. angustijolia in two different ways, with or without persistence 

 of a rim of cytoplasm from the mother cell. In V. stricta the 

 cytoplasm always persists in this manner, forming, even at the 

 first mitosis of the microspore mother cell, a deeply stained border 



60 



62 



63 



Figs. 60-63. — Comparison of florets at time of first mitosis in pollen mother cells' 

 fig. 60, V. angustijolia; fig. 61, V. stricta; fig. 62, intermediate form between V. stricta 

 and V. hastata; fig. 63, V. hastata; X35. 



around the central portion where the mitosis is occurring (figs. 64, 

 65). In V. hastata no such cytoplasmic border is ever formed 

 around the microspores, but all of the cytoplasm of the mother 

 cell is utilized in the production of the pollen grains. The inter- 

 mediate form is like V. hastata in this regard (figs. 66-68). 



V. angustijolia has 8 chromosomes as the 2X number. A late 

 prophase and metaphase of the first reduction division in this 

 species are shown in profile view in figs. 69 and 70. The other 3 

 forms have 12 chromosomes as the 2% number. A metaphase of 

 V. stricta and an early anaphase of the intermediate form from the 

 side and end are illustrated in figs. 7 1-74. I regret that in V. hastata 

 I was unable to find just the same stage to compare with these, as 

 all of my material of this species is either a little too early or too 



