STARCH. 109 
common central point of the granules, which, in consequence of 
unequal growth, are mostly not uniformly round; in granules 
of very eccentric construction, however, the layers are in the 
form of immeasurably thin shells on the side having the slight- 
est growth. The layers (Fig. 35) originate through an abrupt 
variation in the amount of water of the separate zones. An 
outermost layer containing but very little water is followed by 
one with an abundance of water, then again by one poor in 
water, e¢ cetera. The centre of the granule, the nucleus, is very 
rich in water, 
Fic. 35.—Starch granules with very distinct layers and hilum, from the potato, very 
highly magnified. 
If the starch granule advances no farther in growth, a cavity 
(hilum) generally remains in place of the nucleus. This space is 
often confined within a very small compass, and therefore appears 
asa small, dark point (nucleus-point) i in the starch of the potato 
and of the rhizomes of some Zingiberacee (Figs. 36 and 46). In 
the starch granules of Zuber Colchici, Maranta (Fig. 45), 
Maize (Figs. 48 and 49), Radix Calumbe and others, the some- 
what larger hilum often assumes the form of a star or a cross 
(Fig. 37), and in many seeds from the family of Leguminosex, as 
in Semen Calabar and the Bean, the hilum is proportion- 
