274 BOTANICAL GAZETTE [april 



Euphorbia splexdens 



Embryo sac 



The flowers of this species develop just as do those of E. Preslii, 

 and there is also a similarity in the general structure of the obturator 

 and the ovule. As in E. Preslii, the megasnore 



mother cell ma\ 



iguished before the integuments have begu 

 mother cell is easily recognizable by its 



times 



fact that it contains a very large nucleus. It is situated 3 layers 



gh in numerous 



found it only in this position, it is probable that in this species also 

 it originates as a subepidermal cell and that the cells of the nucellus 



comes to lie more deeDlv in 



mo 



and 



STOWS 



At the 



moved 



the micropylar end of the cell. One unusually favorable prepara- 

 tion showed a late anaphase of the heterotypic division (fig. 37). 

 The spindle in this figure occupies a central position and its long 

 axis lies in the plane of the long axis of the nucellus. There are 

 12 small, nearly spherical daughter chromosomes in each of the 

 2 groups on the spindle. 



Although the formation of the row of 4 megaspores was not 

 observed, it is certain that 4 are formed, for when the functional 

 megaspore has increased in size (fig. 38), 3 dark-staining masses 

 can be distinguished at its micropylar end. This stage agrees with 

 the corresponding one in E. Preslii, in which it is plainly the inner- 

 most of the 4 megaspores that develops into the embryo sac. Thi 

 megaspore (fig. 38), even at the division of its nucleus, is not as 

 large as the megaspore mother cell. In one case (fig. 39) 2 develop- 



found 



the nucellus. Each has a 



dark-staining mass of apparently 3 disintegrating cells at the micro 

 pylar end, but the number of these cannot be distinguished witl 

 certainty. This occurrence of 2 functional megaspores is doubtles 

 very unusual, for it was observed in but one ovule. 



