cti and others, may be found in the steppes and sandy plains of
South America, verdant and healthy, though no rain may fall to convey
fresh sap into them for months, or even a year. In the form of
mucilage, _i. e._, gum in a state of solution, it is found in a very
large number of plants, and thus contributes to the maintenance of man
and animals. In these it is generally associated with some other
principles, which render it either more palatable or more easily
digested. A very large number of our esculent vegetables owe their
nutritive properties to the gummy matters with which they abound, and
the favour with which they are regarded to the other matters united
with it. Those which have a bitter principle are very excellent, when
this is in small proportion; and as, in most of them, the gummy matter
is prepared first, requiring for its formation only a moderate degree
of light and heat, while the bitter, or other principle, is added at a
later period, under the influence of stronger light; such plants, when
young, are tender and agreeable; nay, even very poisonous plants, when
very young, are wholesome and pleasant, which, at a more advanced
season, are virose and disagreeable. Thus, the peasantry of France and
Piedmont eat the young crowfoots (ranunculus) and poppies, after
boiling them, and find them safe and nourishing. The same result
follows exclusion of light, as in the process of blanching, by which
means celery, sea-kale, and other vegetables, are rendered esculent,
which in the wild state are poisonous or repulsive. In northern
latitudes, the light being intense for a short time only, many plants
are used there which, in the southern, are dangerous or destructive,
such as hemlock and monkshood. A moderate degree of bitterness is a
very useful accompaniment of the gum, which alone is cloying and even
oppressive to the stomach. The presence of a bitter principle in many
lichens promotes their digestion, and thus even the tough and leathery
ones, called tripe of the rocks, can be eaten, and sustain life amid
great privations and sufferings. The rein-deer moss (_cludonia
rangiferina_) is another lichen of great utility: it is not much
employed as human food, but it is the main support of the rein-deer
for a great portion of the year, and thus renders Lapland a fit abode
for man.

A peculiar modification of gum constitutes _pectine_ or vegetable
jelly; and this occurs in fruits, such as the orange, currant, and
g