stem of the branches elongates, these
pairs of leaves are found scattered along its length, and it is only in
the ears, or spikes of some genera, that we find them growing so
compactly on the axis as to form a close head.

Of this law of growth the palm known as the baccaba is an admirable
illustration, its leaves being disposed in pairs one above another at
the summit of the stem, but in such immediate contact as to form a thick
crown. Its appearance is in consequence totally different from any
other palm, except perhaps the jacitara, which has a slender, winding
stem. Sometimes the crown is more open, as in the inaja--Maximiliana
regia--in which the stem is not very high, and the leaves grow in cycles
of five, separating slightly, so as to form an open vase rising from a
slender stem.

Professor Agassiz remarks that the rest of this tropical forest is as
interesting to the geologist as to the botanist, as it reveals to him
its relation to the vegetable world of past ages, showing those laws of
growth which unite the past and the present.

The tree-ferns--the chamaerops, the pandanus, the araucarias--are modern
representatives of past types. The former is a palm belonging to the
ancient vegetable world, but having its representative in our days. The
modern chamaerops, with its fan-like leaves spreading on one level,
stands, with respect to its structure, lower than the palms with pinnate
leaves, which belong almost exclusively to our geological age, and have
numerous leaflets ranging along either side of a central axis. The
young palms, while their elders tower fifty feet above them, are often
not more than two inches high; and to whatever genus they may belong,
invariably resemble the chamaerops,--having their leaves extending
fan-like on one plane, instead of being scattered along a central axis,
as in the adult tree. The infant palm is, in fact, the mature
chamaerops in miniature; showing that among plants, as among animals--at
least in some instances--there is a correspondence between the youngest
stages of growth in the higher species of a given type, and the earliest
introduction of that type on earth.

More gregarious in their habits than most other palms are the urucuri
palms--Attalea excelsa--groves of which beautify the higher lands, and
grow in vast numbers under the crowns of the more lofty ordinary
forest-trees; their smooth columnar stems being generally fifty feet in
height, while their broad,