Bot.— Vol. I.] CAMPBELL— SPARGANIUM. 299 



The outer integument extends above the inner one and its 

 upper margins are somewhat enlarged, so that the micropyle 

 is quite closed. 



II. The Embryo-Sac. 



The youngest embryo-sacs met with had the egg-appa- 

 ratus and antipodal cells developed, and nothing can be 

 stated as to their early history. As the ovule at the time of 

 fertilization is of the ordinary type, it is not probable that 

 there are any marked deviations from the type in its early 

 development. 



In S. simplex (figs. 3, 8) the mature embryo-sac is 

 broadly oval in outline and is covered at the apex by about 

 two layers of nucellar cells, the central ones somewhat elon- 

 gated, so that the apex of the nucellus is slightly pointed. 

 At the sides there are about four layers of cells in the 

 nucellus, and these remain permanently and are not de- 

 stroyed by the developing embryo-sac as so often happens. 

 Within the embryo-sac the granular cytoplasm is principally 

 confined to a thin parietal layer, except that surrounding 

 the primary endosperm-nucleus there is a considerable 

 amount of granular cytoplasm. 



In S. Greenii (fig. 5) the two carpels are completely 

 united. A section of the ovary shows a long central pla- 

 centa formed by the coherent inner faces of the carpels, 

 and from the upper part of the placenta depend the two 

 ovules. These correspond in structure with those of S. 

 simplex but are somewhat longer and more slender, although 

 they are less constant in form than in that species. The 

 embryo-sac is longer and narrower and more pointed at the 

 ends. The part of the nucellus above the apex of the 

 embryo-sac is thicker, there being usually about four layers 

 of cells at this point. 



Sparganhim longifolium is much like S. simplex in the 

 form of the pistil, except for the shorter style and small 

 stigma. The ovule is of about the same size and shape, 

 and the embryo-sac, so far as could be judged from the 



