a dry soil is
therefore more adapted for its cultivation. As blossoms are
occasionally plucked from potato plants, so the manihot or cassava is
deprived of its buds to increase the size of its roots. The raw root
of the bitter species, when taken out of the ground, is poisonous--if
exposed, however, to the sun for a short time, it is innocuous, and
when boiled is quite wholesome.

The starch of the root of the manioc is prepared in the following
manner, as described by Dr. Ure:--" The roots are washed and reduced
to a pulp by means of a rasp or grater. The pulp is put into coarse
strong canvas bags, and thus submitted to the action of a powerful
press, by which it parts with most of its noxious juice. As the active
principle of this juice is volatile, it is easily dissipated by baking
the squeezed cakes of pulp upon a plate of hot iron. The pulp thus
dried concretes into lumps, which become hard and friable as they
cool. They are then broken into pieces, and laid out in the sun to
dry. In this state they are a wholesome nutriment. These cakes
constitute the only provisions laid in by the natives, in their
voyages upon the Amazon. Boiled in water, with a little beef or
mutton, they form a kind of soup similar to that of rice.

The cassava cakes sent to Europe are composed almost entirely of
starch, along with a few fibres of the ligneous matter. It may be
purified by diffusion in warm water, passing the milky mixture through
a linen cloth, evaporating the straining liquid over the fire, with
constant agitation. The starch, dissolved by the heat, thickens as the
water evaporates, but on being stirred it becomes granulated, and must
be finally dried in a proper stove.

2. Bitter cassava (_Janipha Manihot_, of Kunth; _Jatropha Manihot_, of
Linnaeus; and _Manihot utilissima_, Pohl).--This species has a knotty
root, black externally, which is occasionally 30 lbs. in weight. In
the root there is much starchy matter deposited, usually along with a
poisonous narcotic substance, which is said to be hydrocyanic acid.
The juice of the plant, when distilled, affords as a first product a
liquor which, in the dose of thirty drops, will cause the death of a
man in six minutes. It is doubted whether this acid pre-exists in the
plant; some suppose it to be generated after it is grated down into a
pulp. It can be driven off by roasting, and then the starch is used in
the form of cassava bread. It is principally from the starch of the