The evening telegraph. [volume] (Philadelphia [Pa.]) 1864-1918, 1867-02-21


arbitrary distinction, when you hear described
these radiate animals, with reference to which
is the right and which the left side which is
the part that is above, and which is the part
that is below.
PEcULIARITIEs OF THE MoLLUsKs.
Not so with the molusks. They have in
ternal features, which determine their relations,
their symmetry, and fix the position of their
parts i'm manner which enables us to distin-
guisb the anterior or head end from the pos
terror or tail end as well as the right and left
and above and below. To this group of animals
belong all the shell-fshes-the CLANS oysters,
and the like the snail and the cuttle-fshes
also. Part of them are aquatic animals that
inhabit the sea, part of them are fresh water
fishes and part of them are terrestrial animals.
So you see, here we have animals of one and
the same structure inhabiting the different
elements, which were made in the infancy of
our science, the foundation of the classification
of the whole animal kingdom. Of this type
there are several classes-three classes-and to
them / shall refer presently, as we have
number of representatives of them in the fresh
water animals of the Amazon. Let me say that
the majority of those which have two valves
are either fresh water or marine, the greater
part, however, marine, and the less are fresh
water. OF those which have only one valve
and are generally wound up in a spiral, we
have also a majority in the sea, but some in
fresh water, and some on land. Of the cuttle-
fish class there are none in fresh water, none
are terrestrial, but all of them are marine. And
they have been inhabitants of our globe from the
very earliest periods of the earth's history
during which animals have lived upon it. l
may represent the formula of these animals
in this way illustrating on the blackboard)
the anterior end marked by some prominent
feature which indicates something of a head.
Not all, however, have the anterior end very
hn LONGITUDINAL
axis, on the side of which organs are arranged.
For instance, in the oyster there is a pair of
gills on each side, so that the respiratory
organs are placed on the right and on the left;
while about the sides of the mouth are those
fiat appendages, with the aid of which these
animals introduce food into their mouths, and
the organs, the intestines the ovaries, the
heart, and the organs of respiration are clus-
tered in the centre. Now, the manner in
which these several parts are protected by
shell are accessory details of their structure,
which cause the different families, different
generas, and different species.
THE ARTIcULATEs.
Then we have another group which are
called articulates, animals the body of which
may be compared to a cylinder, or to a tube,
but tube divided into number of rings,
movable one upon the other, so that, i'll fact,
the body is an articulated cylinder containing
organs. l represent that in this way (makes
a drawing); these transverse rings in this man
ner; the internal organs arranged i'll the inte-
riOr; the alimentary canal i'll the interior; the
respiratory organs i'll the upper part; the ner-
vous system mainly in the lower part; the
respiratory organs upon the sides; and on the
rings are frequently locomotive appendages in
the shape of limbs, which may be mere hoops,
as i'll the case of the worms, or may be articu-
lated limbs, as in the case of crabs, Holsters,
insects, and the like. Now, these articulated
animals embrace also several classes of such
worms, of which there are marine kinds and
fresh water kinds, and terrestrial kinds. 1t is
one of the class which has the most eXtraordi-
nary distribution, for worms are found every
where. They are found even as parasites in
the bodies of other animals in the internal
organs of other living beings they are found
in fresh water and salt water, and also in the
earth, burrowing under the ground.
IDENTITY OF STRUCTURE.
Then we have the class of crabs, the crus-
taceans, which is next above, and that of in
sects which contain animals breathing air and
living out of the water. So that we have here
again, animals of an aquatic, or terrestrial, or
aerial mode of life, all showing one and the
same structure. l like to insist upon these
facts, which are most brilliant results of
modern progress or science because you see
at once what bearing they have upon the
question of the origin of these things. If we
have identical structures under the most di-
versifed conditions of existence, these external
things which act upon living beings cannot
have been the cause which has produced such
unity of plan. The unity of plan-that ideal
common basis of anmals-must be derived
from something higher than the conditions i'll
which these animals live when we find that,
notwithstanding these diversified conditions,
the animals present one and the same plan and
structure. (Applause.) The next type is
that of vertebrate. 1t is one which has a special
interest for us, for we belong there Qaugh-
ter) and with us all the animals which have
a backbone, all the animals which have an in
ternal solid axis so arranged as to surround
two distinct cavities in which the various
organs of the body are inclosed, one cavity
below that axis in which all these parts or all
those systems of the organs are contained by
which life is maintained in its normal condi-
ton, These are the organs of digestion
through which food is assimated and trans
formed for the sustenance of the body, the
organs of breathing in which this assimilation
is tosteled, the organs of circulation through
which the result of these operations is circu-
lated through the system, and also the organs
Of reproduction. All these organs by which
animal life is simply maintained are CON
tanned in the lower cavity of the body, while
an upper cavity contains organs which
establish the relations between the animals
and the surrounding world In that upper
cavity is contained, in the anterior part of the
body. the BRAIN and in the middle and posterior
parts Of the body the proongatiOn of the brain
which we call the spinal marrow. From it
arise the nerves. which are scattered through