The evening telegraph. [volume] (Philadelphia [Pa.]) 1864-1918, 1867-02-21
Prof. Agassiz's Lecture on the
Fishes of the Amazon.
Their Species, Habits, characteristics,
and Commercial Value.
Eto., Etc, Etc, ETC., Etc" ETC.

HrOt. AgaSSE, lne great hLh0iiO"h
and savan, having recently returned from
journey of scientific exploration in South Anne
rica, is now engaged in making his discoveries
known to the world in a series of lectures at
The Cooper Institute, in New York city.
We have already given sketches of several
previous lectures, and we now reproduce a
perbatira report of the most interesting address,
that upon the Fishes of the Amazon''-a sub
ieot fraught with vital import in the scientific
world, and, as eliminated by Agassiz is full of
that popularity and simplicity that charm the
million.
STATEMENT OF THE SUBJECT.
Ladies and conference.-the aquatic popu-
lation of any extensive fresh water basin has
many points of interest: We may, in the first
place, view it in reference to the structure of
these animals, as compared with that of aerial
and terrestrial beings We may examine them
with reference to their geographical dstribu-
ton as contrasted with those which inhabit the
sea or the land. We may also examine them
with reference to their variety, or the diversity
which exists among them, under apparently
identical circumstances. This last point is one
of peculiar interest; because you will perceive
that if external, circumstances have had deep
influence in bringing about the variety of
living beings which we find everywhere on the
surface of the earth, we should expect to find
great similarity among animals living close
together, under identical circumstances,
shut out from the influences of the
great changes which are constantly
taking place in the atmosphere, shut out from
the great diversity of the bottoms which are
found along the sea-shOres, and circumscribed
within limits very similar. Now, the Amazon,
above all the rivers of the EARTH presents a
variety of organized beings whichis stupendous,
which exceeds all conception, and which was
a matter of surprise even to me, who had de-
voted my life chiefly to the study of fishes.
will, therefore, try to give you some idea of
this diversity. l regret only that cannot sud-
denly impart to you the interest which have
felt for a long time in these animals. Unknown
and uninteresting in their ways, they have
generally been neglected. Few naturalists
have turned their attention to them, and am
afraid you will find my lecture rather mono
tonous. Yet, if you will for a moment consider
that a knowledge of these beings has an i'm
portant bearing on some of the most important
questions which are now under discussion
among naturalists, | hope you will follow me
in the details which | am about to submit to
you.
PIscAToRIAL STRUCTURE.
But first allow me to say a few words CON
cerning the structure of aquatic animals. In
the infancy of our science, animals were classi-
IS,
according to the conditions under which they
are found in nature. If you will turn over the
works of the great naturalists of the eleventh
century, you will find that their descriptions
of the animals then known are arranged under
but few heads, one embracing the aquatic ami
mails, another the terrestrial or creeping ami
mails, and the other the aerial or flying animals.
But in proportion as our information of the
structure of all these beings has been growing,
it has been found that these external influences
do not so modify organized beings as to bring
together in the same habitation those which
have the closest resemblance; and we are no
longer surprised now to find in the water ami
mails of the most diversified classes, or to find
the same diversity among those which either
inhabt the land or live III the air. 1t has been
the result of modern investigation to discover
that animals, however numerous however
varied, are, after all, built upon four plans of
structure only. Those plans are very simple,
and may be recognized easily; and these sys-
TENS may be expressed by formulas so simple
that you will permit me for a moment to call
your attention to that point.
CURIOUS FORMATIONS.
There are animals which have all parts ar
ranged like rays around central axis-that is
they are radiated in structure and a figure
like this (draws a sta-shaped character on the
blackboard) may be considered as n formula
Suppose that I'VE consider any organ the sto-
mach for instance it will be found to have five
pouches radiating in five different directions.
Suppose that we consider the nervous system
it will be found to consist of five rings. five
swellings, with the same directions as the five
pouches of the stomach; five rays or threads
having the same direction, and NAV be at the
ends of the threads there may be ewes. The
ovaries will be arranged in the same manner.
with a bunch of eggs here, bunch of eggs
here bunch of eggs here, and another there.
And all those parts are so arranged around a
central axis, that they are like spokes of a
Wheel-rays around a vertical axis and in that
axis we have the mouth at the centre. So
these animals owing to this popularity Of con-
stitution, are justly called Radiates. Now, OF
those we do not find any in the Amazon. We dc
not find any in the fresh waters except one,
the simplest kind of polyp, the fresh water
pOlyp, or bush poyp, as it is called; this IS the
only fresh water specimen Of that large family
which is innumerable in salt water, such as
the elly-fshes, star-fshes, and sea-urchins-
in fact most of the animals that inhabit the
sea, and which have existed not only at al
times during geological periods anterior tc
ours but which are now common everywhere
in the ocean, but which have no representa-
tive on land, and but few very simple ones
i'm the fresh waters of the temperate zone
Another group, which are called mollusks,
embrace animals the body of which is SYM
metrical the parts of which are arranged
around two sides of a longitudinal axis, sC
that these animals have an anterior and a
posterior part-a part that is above and part
that is below--a right and left, which is not
go ,,;+I, tI,a radiateg for these radiates