62 HOW CROPS GROW. 
AMOUNT OF CELLULOSE IN PLANTS. 
Per cent. b Per cent. 
Potato tuber...........- pie Red clover plant in flower...10 
Wheat kerncl..........- 3.0 As BE MOY sie scat lasses is oewrete 34 
Wheat meal..........-.. 0.7 Timothy NOES ta arate Giasbccmniayere 23 
Maize kernel............ 5.5 Maize CODS...... cece ceee eee 38 
Barley sg pasrvecensae 8.0 Oat straw.....cseeeeees +640 
Oat ae eT 10.3 TWiseat as caer peeen hyn 48 
Buckwheat kernel....... 15.0) RYy6 © caustics esate oes 54 
Starch, C,, H,, O,,.—The cells of the seeds of wheat, 
corn, and all other grains, and the tubers of the potato, 
contain this familiar body in great abundance. It occurs 
also in the wood of all forest trees, especially in autumn 
and winter. It accumulates in extraordinary quantity in 
the pith of some plants, as in the Sago-palm, (Metroxylon 
Rumphit,) of the Malay Islands, a single tree of which 
may yield 800 lbs. 
Starch occurs in greater or less quantity in every plant 
that has been examined for it. 
The preparation of starch from the potato is very sim- 
ple. The potato contains, on the average, 76 per cent wa- 
ter, 20 per cent starch, and 1 per cent of cellulose, while 
the remaining 3 per cent consists mostly of matters which 
are easily soluble in water. By grating, the potatoes are 
reduced to a pulp; the cells are thus broken and the starch- 
grains set at liberty. The pulp is then agitated on a fine 
sieve, in a stream of water. The washings run off milky, 
from suspended starch, while the cellulose is retained by 
the sieve. The milky fluid is allowed to rest in vats until 
the starch is deposited. It is then poured off, and the 
starch is collected and dried. 
Wheat-starch is commonly made by allowing wheaten 
flour mixed with water to ferment for several weeks. By 
this process the gluten, etc., are converted into soluble 
matters, which are removed by washing, from the unalter- . 
ed starch. 
Starch is now largely manufactured from maize, A 
