



i9i 7 J WENIGER— EUPHORBIA 277 



may 



charging its nuclei, while in another case the endosperm nucleu- 

 may have undergone several divisions. Figs. 48 and 50 were drawn 

 from 2 embryo sacs within the same ovary. 



Embryo 



The fertilized egg does not divide immediately after the fusion 

 of the nuclei within it. Usually there are 5 or 6 nuclear divisions 



perm 



In the sac 



erm 



undivided. The first division of the egg (fig. 51) is at right 

 angles to the long axis of the nucellus. The developing embryo 

 forms a short suspensor which is several cells in diameter. The 

 terminal cell divides by a longitudinal wall after the embryo is about 

 4 cells in length (fig. 52). There seems to be nothing definite about 

 the planes in which later walls are formed (figs. 53, 54), but a more 



£> 



mass 



suspensor (figs. 55, 56). In the embryo represented in fig. 56 the 

 suspensor seems to be disintegrating. The mature embryo has 

 a structure similar to that of E. Preslii, there being a well differ- 

 entiated root cap and epicotyl. 



Summary 



1. The cyathium of both species studied begins as a papilla 

 which arises between two bracts. The order of appearance of the 

 parts of the cyathium is as follows: staminate flowers, involucre, 



branch 



pel 



2. The megaspore mother cell is subepidermal in origin in 

 E. Preslii, and probably also in E. splendens. 



3. An axial row of 4 megaspores is formed, the lowest of which 

 develops into the embryo sac; the other 3 spores disintegrate. 



4. The inner integument begins to develop before the outer, but 

 the latter grows rapidly and soon overtops the inner. 



5- The mature embryo sac is long and narrow, and is deeply 

 imbedded in the tissue of the nucellus. In E. Preslii it has the 



