Page:The Atlantic Monthly Volume 9.pdf/15
on
one such plans
is
in
of
In
or
except
in of
lose sight prevalent
diates metry
sym
the bilateral
the other three,
very subordinate
structure; the plan
element
this lowest type parts which vertical axis.
all
Of
ascer
joints end into transverse rings upon each other. the Ra
Articulates,
then, that these largest divisions the animal kingdom are based, but sim ply upon the general structural idea. Striking this statement was, was
to in a
is
by
it
as
at
of
of
us
a
it
Ehrenberg also,
Invertebrates.
at a
and
later period, announced another division under two heads, those with continu ous solid nervous centre, and those with
–
scattered
But
there was
ther
nervous
swellings."
real progress these latter classifications,
ei
merely
far
to
of
or
on
so
on
a
of
or
of
of
to
of
or
Lamarck,
back
For more details upon the different sys Zoology, see Agassiz's Essay Clas sification his Contributions the Natural History the United States, Vol. on
tems
I.
either
the circulating fluids, that presence the absence
to
In
parts are here again arranged
will bring animals together whatever classify them; set features we try Aristotle, founded on that the division
in
in
the Articu but one cavity, and the parts.
on
is
dividualization
of
a
is a
try either side the body, but the body has but one cavity, and soft, concentrated mass, without distinct
based
of
of
on
to a
the Mollusks, also, the parts are arranged according bilateral symme
between systems different foundations may teach that every structural combination in cludes certain inherent necessities which
This coincidence
ma.
of
In
of
of
on
a
double internal cavity. The parts are symmetrically arranged either side the longitudinal axis the
Aristotle, under the head animals with without blood, the Enaima and Anai
us
col be
of
as
the primary divisions are concerned; for they correspond the old division
on
a
in
low, forming
in
be
the Verte column ter
minating prominent head; this umn has an arch above and an arch
lates there
not this principle, distributed the animal kingdom into two great divisions, which calls Vertebrates the truth
is a
stated
In
these plans may
the most general terms. brates there vertebral
body.
ani
in
on the
departures
principle are away from the the true affinities among
but lead
of
of
Each
do
from errors, and recognition animals.
in
been made
his classification, great fundamental
key
the
affinities among Lamarck, his contemporary, the natural
mals. recognizing
us
its
details
at
and many
but though some
of
to
tempts change improvements have
new road for study, and gave
so
Cuvier's,
it;
this division
all
of
to
every naturalist. tial There have been many criticisms
classification was opened but
a
is
built
the plan now essen
cause, his principle not fully appreciated; note
the
Whatever the
his views.
of
structure is
read the finished on which the whole
grandeur
he
on
in
of
of
to
of
a
in
strange city, who looks ler the him, exterior edifices entirely new but knows nothing the plan their internal architecture. To be able to
haps there was also some jealousy
no
like the travel
of
this,
coldly received contempora first naturalists: they could hardly grasp Cuvier's wide generalizations, and per
to
can
he is
Till
do
he
to
of
animals, number must penetrate deep enough into their organization find the secret of their internal structure.
of
certain
he
a
of
characteristic
—
features
a
to
it
no
as
of
With this new principle the basis investigation, longer enough for was the naturalist know certain amount of
features,
of
Radiates.
sphere,
ry
and
organic
bear definite relations not upon any special
It
he
structural Cuvier found the whole animal kingdom only four, which called Vertebrates, Mollusks,
is
another
these plans. conceptions
by
to
at
of
in or or
true relations with other animals taining whether they were built
end
movable
of
that animals
a
was found
whose affinities had been questionable before were now once referred their
the longitudinal axis, but these animals the whole body divided from side
to
it
to
its
The value of this principle was soon application tested by facts already
known, and
[January,
Study in Natural History.
of
of
as so we
Methods
an
4