at one object, itself healthfully enjoying life, and
fulfilling its own proper ends of being, should be a microcosm, on which
another range of life should find its sphere, and on which it should
disport, as on an independent world. I have often admired, in the
gorgeous tropical forests, what a wilderness of vegetation a single
tree supports; what numbers of orchids and wild pines spring out of the
forks, what creepers and lianes hang and twine about its branches, what
elegant ferns cluster on the horizontal limbs, what snake-like cacti
creep from bough to bough, what mosses, and jungermanniae crowd in every
crevice, what many-coloured lichens stud the rugged bark! And then
animal life is swarming in all this great field of parasitic vegetation.
Reptiles and birds, snails and slugs, insects and millepedes, and
spiders and worms nestle by thousands in such prolific situations, so
that a great old tropical tree, one of the giant figs or cotton-trees,
is a very museum in itself.

And in my wanderings along the sea-edge here at home how often have I
been amazed at the diverse population, plant and animal, which crowds a
single oar-weed, or tangle! The stem fringed with delicate red-weeds, as
the minute _Rhodymeniae_, and _Polysyphoniae_, and _Callithamnia_; the
tortuous roots studded with Anemones, with _Flustrae_ and _Lepraliae_, and
multitudes of other _Polyzoa_, with tiny Polypes of many kinds, with
Barnacles and Limpets, and sheltering small Crustacea, and Mites, and
Annelids by scores.

Mr Darwin has an interesting passage on this subject, evoked by the
profusion of parasitic life on the long sea-weed of Cape Horn
(_Macrocystis_). "The number of living creatures" he remarks, "whose
existence intimately depends on the Kelp is wonderful. A great volume
might be written, describing the inhabitants of one of these beds of
sea-weed. Almost all the leaves, excepting those that float on the
surface, are so thickly incrusted with corallines as to be of a white
colour. We find exquisitely delicate structures, some inhabited by
simple hydra-like polypi, others by more organised kinds, and beautiful
compound Ascidiae. On the leaves also, various patelliform shells,
Trochi, uncovered molluscs, and some bivalves are attached. Innumerable
crustacea frequent every part of the plant. On shaking the great
entangled roots, a pile of small fish, shells, cuttle-fish, crabs of all
orders, sea-eggs, star-fish, beautiful Holuthuriae, Planari