, to the influence of
climate, since a particular kind of aliment, which is very appropriate
in one country is improper in another; thus, as we advance from the
equator towards the poles, the necessity for animal food becomes
greater, till, in the very north, it is the sole article of
subsistence. Animal food, from containing nitrogen, is more
stimulating, and, therefore, less suitable for hot climates, where, on
the contrary, saccharine, mucilaginous, and starchy materials are
preferred; hence, in the zone of the tropics, we find produced in
abundance rice, maize, millet, sago, salep, arrowroot, potatoes, the
bread-fruit, banana, and other watery, or mucilaginous fruits.
Quitting this zone, we enter that which produces wheat, and here,
where the temperature is lower, providence has united with the starch
of this grain a peculiar principle (gluten), possessing all the
properties of animal matter, and yielding nitrogen and ammonia in its
decomposition[E]. Thus, by a gradual and almost insensible transition,
nature furnishes to man the food which is most appropriate for him in
each region. In the subtropical zone vegetable diet is still
preferred, but, in chemical constitution, the favourite articles
approximate animal substances. This holds also in the temperate zone,
not only in respect of wheat, but also in the chesnut, which is almost
the sole means of subsistence in some of the mountainous regions of
France, Italy, and Spain, though, instead of the gluten of wheat, this
seed contains albumen, the relation of which to animal food is even
closer than that of gluten. In reviewing the geographical distribution
of the cereal grains[F], we find that starch nearly pure is produced
in the greatest abundance in the hottest parts of the world,
particularly in rice and maize; it becomes associated in the
subtropical regions with an equivalent for animal food; and in still
colder regions, where wheat fails, oats and barley take its place.
These, though possessed of less gluten than wheat, are, nevertheless,
more heating, and, therefore, better calculated for northern
latitudes. The inhabitants of Scotland and Lapland, with their oaten
and barley or rye bread, are thus as thoroughly provided with the best
food, as the Hindoo with his rice or Indian corn[G].

It would be impossible to enumerate the plants which furnish starch in
large proportion, but a few may be given as illustrative of the above
positions. The chemical analysis