792 



BOTANY AND PHARMACOGNOSY. 



244. RICE FLOUR consists chiefly of the small, angular 

 starch grains and aggregates like those of oat (Fig. 317, E). 

 There are also present some of the polygonal cells containing 

 aleurone grains and a few fragments of the pericarp. The 

 latter is especially characterized by the radially elongated cells of 

 the epicarp, which are 100 to 500 /x long and 25 to 100 /x wide, 

 and the end walls of which are deeply undulate, resembling the 

 epidermal cells of some leaves. 



Fig. 318. Nux Vomica: H, fragments of lignified hairs of seed-coat; B, basal portion 

 of hairs; E, thick- walled parenchyma cells of endosperm containing one or more oil globules 

 and protoplasm; P, isolated protoplasmic substance from endosperm cells. 



245. OATMEAL OR ROLLED OATS. The starch grains 

 are small and, like those in rice, in aggregate masses, which are 

 more or less rounded, polygonal or pear-shaped. The endosperm 

 consists of a single layer of cells containing aleurone grains, but 

 the walls are 3 to 5 ^ thick. The cells of the epicarp are longi- 

 tudinally elongated and possess very thin, porous walls, those 

 situated at the upper end of the grain having long, unicellular 

 hairs, which are about 20 fi wide near the middle portion, and 



