218 IOWA ACADEMY OF SCIENCES. 



Endosperm. — This does not differ from preceding species, as 

 to shape, size and contents of cells. 

 Embryo. — Agrees with B. aquifolium. 



B. NERVOSA Pursh. 



Fruit and seed characters. — Baccate fruit, borne in a long 

 raceme, blue with glaucous bloom, globular three to four lines 

 long, one to two seeded. Seeds brown, oblong, curved at 

 base, two lines long, two-sided or terete; raphe extends along 

 the edge of the narrow side, prominent. Testa shining, slightly 

 pitted, chalaza at tip of seed, hilum and micropyle adjacent. 

 The hilar pit smaller than in H. Thunbergii. 



Epidermis. — ^The cuticle well developed, forming a continu- 

 ous zone on the outer surface, followed by a straw-colored 

 stratified layer, which reaches its greatest thickness where the 

 walls separate, giving this portion a concave appearance. 

 The third layer is also strongly stratified, darker in color and 

 decidedly uneven, presenting the appearance of a series of 

 cone-shaped depressions, around which the lines curve. A 

 narrow connection occurs between this and the middle portion 

 of cells, where the wall is thicker than below. This again 

 connects with a thickening in lower part of wall. The internal 

 part of wall is lighter in color and strongly stratified; walls are 

 greatly thickened, with a small cell-cavity. The cells are 

 lighter in color than in nutrient and pigment layers. 



Nutrient layer. — Structure same as in last species. Cell- 

 walls much darker in color in lower part of parenchyma. 



Parenchyma layer. — This layer is much compressed, and con- 

 sists of thin-walled cells. In some places poorly defined. 

 Cells contain protein grains. 



Endosperm. — First layer of cells smaller, with thickened outer 

 walls, cells below larger except a narrow zone next to the 

 embryo; the latter are elongated, thick walled, and contain but 

 a small amount of granular matter. The cells of endosperm 

 contain no starch, but an abundance of fat and protein grains. 

 Cell-walls made up of cellulose. 



Embryo — First row of cells regular, somewhat longer than 

 broad, with thickened outer walls, much smaller than those 

 below, filled with protein grains and fat, but no starch. 



