40 



BOTANICAL GAZETTE 



[JANUARY 



The earliest material was collected during the first week in April. 

 At that time the ovules appear as minute protuberances from the 

 base of the ovary, the inner integuments have just begun to show, 

 and the cells of the nucellus are as yet undifferentiated. The o\iile 

 grows with great rapidity, the outer integument soon appears, and 

 the inner integument passes beyond the apex of the nucellus. At 

 the same time the nucellus itself increases greatly in size^ and the 



13 



Figs 



division i 



The 



Figs. 9, 10. Second 

 embryo sac. X920 



Fig. 12, Embryo sac after fusion of polar nuclei; index letters suggest the structures 



X 920, 



^rm 



X920- 



archesporial cell^ recognizable by its greater size and more definite 



cells 



makes its appearance in the hypodermal layer 

 >llowed by a periclinal division of the epidermal 



of the nucellus. The first two divisions of the arc! 

 cell are by anticlinal walls at right angles to each other, thi 

 rise to four sporogenous cells lying side by side (figs. 4, 5). 

 these outstrips the others in its growth, crowding them and 



porial 



cr 



One of 



rounding: cells 



o 



undergoes one trans\ 



which a small cell, frequently wath an ill-defined 



(fig 



petal cell, or one of a "row of tW' 



9f 



formed by a mother cell, was not determin 



At this stage the 



