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CELL CONTENTS 185 
In some forms—e.g., belladonna root (Plate 75, Fig. 2) the 
compound grains are more numerous; while in sanguinaria the 
simple grains are more numerous, etc. 
OUTLINE 
The outline of starch grains is made up of (1) rounded, (2) 
angled, and (3) rounded and angled surfaces. 
Starch grains with rounded surfaces may be either spherical, 
as in Plate 74, Fig. 3, or oblong or elongated, as in Plate 71, 
Fig. 1. 
tothe: starches with rounded surfaces are shown on Plates 
He and 73. 
Angled outlined grains are common to cardamon seed, white 
pepper, cubebs, grains of paradise (Plate 76, Fig. 4), and to corn 
(Plate 70, Fig. 3). 
The outlines of all compound grains are made up partly of 
plane and partly of curved surfaces. 
SIZE 
The size (greatest diameter) of starch varies greatly even 
in the same species, but for each plant there is a normal variation. 
In spherical starch grains the size of the individual grains is 
invariable, but in elongated starch grains and in parts of com- 
pound grains the size will vary according to the part of the grain 
measured. In zedoary starch (Plate 71, Fig. 4), for instance, 
the size will vary according to whether the end, side, or surface 
of the starch grain is in focus. 
The parts of compound grains often vary greatly in size. 
Such a variation is shown in Plate 75, Fig. 2. 
HILUM 
The hilum is the starting-point of the starch grain or the 
first part of the grain laid down by the amyloplast. The hilum 
will be central if formed in the middle of the amyloplast, and 
excentral if formed near the surface of the amyloplast. It 
has been shown that the developing starch grain with eccentric 
hilum usually extends the wall of the amyloplast if it does not 
actually break through the wall. Starch grains with excentral 
hilums are therefore longer than broad. 
