creature being alarmed will probably at first remain motionless. But
very soon it will begin to play in the water, rising and falling, and
swimming gracefully from side to side. Now you will notice a curious
effect, for the bands will glitter and become tinged with prismatic
colors, till, as it moves more and more rapidly these colors,
reflected in the jelly, seem to tinge the whole ball with colors like
those on a soap-bubble, while from the two sacs below come forth two
long transparent threads like spun glass. At first these appear to be
simple threads, but as they gradually open out to about four or five
inches, smaller threads uncoil on each side of the line till there are
about fifty on each line. These short tendrils are never still for
long; as the main threads wave to and fro, some of the shorter ones
coil up and hang like tiny beads, then these uncoil and others roll
up, so that these graceful floating lines are never two seconds alike.
We do not really know their use. Sometimes the creature anchors itself
by them, rising and falling as they stretch out or coil up; but more
often they float idly behind it in the water. At first you would
perhaps think that they served to drive the ball through the water,
but this is done by a special apparatus. The cross ridges which we
noticed on the bands are really flat comb-like plates (_p_, Fig. 9),
of which there are about twenty or thirty on each band; and these
vibrate very rapidly, so that two hundred or more paddles drive the
tiny ball through the water. This is the cause of the prismatic
colors; for iridescent tints are produced by the play of light upon
the glittering plates, as they incessantly change their angle.
Sometimes they move all at once, sometimes only a few at a time, and
it is evident the creature controls them at will.
This lovely fairy-like globe, with its long floating tentacles and
rainbow tints, was for a long time classed with the jelly-fish; but it
really is most nearly related to the sea-anemones, as it has a true
central cavity which acts as a stomach, and many other points in
common with the _Actinozoa_. We cannot help wondering, as the little
being glides hither and thither, whether it can see where it is going.
It has nerves of a low kind which start from a little dark spot (_ng_)
exactly at the south pole of the ball, and at that point a sense-organ
of some kind exists, but what impression the creature gains from it of
the world outside we cannot tell.
I am afraid you may think it dull to turn from such a beautiful being
as this, to the gray leaf which looks only like a dead dry seaweed;
yet you will be wrong, for a more wonderful history attaches to this
crumpled dead-looking leaf than to the lovely jelly-globe.
[Illustration: FIG. 10. THE SEA-MAT OR FLUSTRA (_Flustra foliacea_).
1, Natural size. 2, Much magnified, _s_, Slit caused by drawing in of
the animal _a_.]
First of all I will pass round pieces of the dry leaf (1, Fig. 10),
and while you are getting them I will tell you where I found the
living ones. Great masses of the Flustra, as it is called, line the
bottom and sides of my pool. They grow in tufts, standing upright on
the rock, and looking exactly like hard gray seaweeds, while there is
nothing to lead you to suspect that they are anything else. Yesterday
I chipped off very carefully a piece of rock with a tuft upon it, and
have kept it since in a glass globe by itself with sea-water, for the
little creatures living in this marine city require a very good supply
of healthy water and air. I have called it a "marine city," and now I
will tell you why. Take the piece in your hand and run your finger
gently up and down it; you will glide quite comfortably from the lower
to the higher part of the leaf, but when you come back you will feel
your finger catch slightly on a rough surface. Your pocket lens will
show you why this is, for if you look through it at the surface of the
leaf you will see it is not smooth, but composed of hundreds of tiny
alcoves with arched tops; and on each side of these tops stand two
short blunt spines, making four in all, pointing upwards, so as partly
to cover the alcove above. As your finger went up it glided over the
spines, but on coming back it met their points. This is all you can
see in the dead specimen; I must show you the rest by diagrams, and by
and by under the microscope.
First, then, in the living specimen which I have here, those alcoves
are not open as in the dead piece, but covered over with a transparent
skin, in which, near the top of the alcove just where the curve
begins, is a slit (_s_ 2, Fig. 10) Unfortunately, the membrane
covering this alcove is too dense for you to distinguish the parts
within. Presently, however, if you are watching a piece of this living
leaf in a flat water-cell under the microscope, you will see the slit
slowly open, and begin to turn as it were inside out, exactly like the
finger of a glove, which has been pushed in at the tip, gradually
rises up when you put your finger inside it. As this goes on, a bundle
of threads appears, at first closed like a bud, but gradually opening
out into a crown of tentacles, each one clothed with hairs. Then you
will see that the slit was not exactly a slit after all, but the round
edge where the sac was pushed in. Ah! you will say, you are now
showing me a polyp like those on the sertularian tree. Not so fast, my
friend; you have not studied what is still under the covering skin and
hidden in the living animal. I have, however, prepared a slide with
this membrane removed and there you can observe the different parts,
and learn that each one of these alcoves contains a complete animal,
and not merely one among many mouths, like the polyp on Sertularia.
[Illustration: FIG. 11. DIAGRAM OF THE ANIMAL IN THE FLUSTRA OR
SEA-MAT.
1, Animal protruding. 2, Animal retracted in the sheath, _sh_,
Covering sheath, _s_, Slit. _t_, Tentacles. _m_, Mouth. _th_, Throat,
_st_, Stomach. _i_, Intestine, _r_, Retractor muscle, _e_, Egg-forming
parts. _g_, Nerve-ganglion.]
Each of these little beings (_a_, Fig. 10) living in its alcove has a
mouth, throat, stomach, intestine, muscles, and nerves starting from
the ganglion of nervous matter, besides all that is necessary for
producing eggs and sending forth young ones. You can trace all these
under the microscope (see 2, Fig. 11) as the creature lies curiously
doubled up in its bed, with its body bent in a loop; the intestine
_i_, out of which the refuse food passes, coming back close up to the
slit. When it is at rest, the top of the sac in which it lies is
pulled in by the retractor muscle _r_, and looks, as I have said, like
the finger of a glove with the top pushed in. When it wishes to feed
this top is drawn out by muscles running round the sac, and the
tentacles open and wave in the water (1, Fig. 11).
Look now at the alcoves, the homes of these animals; see how tiny they
are and how closely they fit together. Mr. Gosse, the naturalist, has
reckoned that there are six thousand, seven hundred and twenty alcoves
in a square inch; then if you turn the leaf over you will see that
there is another set, fixed back to back with these, on the other
side, making in all, thirteen thousand, four hundred and forty
alcoves. Now a moderate-sized leaf of flustra measures about three
square inches, taking all the rounded lobes into account, so you will
see we get forty thousand, three hundred and twenty as a rough
estimate of the number of beings on this one leaf. But if you look at
this tuft I have brought, you will find it is composed of twelve such
leaves, and this after all is a very small part of the mass growing
round my pool. Was I wrong, then, when I said my miniature ocean
contains as many millions of beings as there are stars in the heavens?
You will want to know how these leaves grew, and it is in this way.
First a little free swimming animal, a mere living sac provided with
lashes, settles down and grows into one little horny alcove, with its
live creature inside, which in time sends off from it three to five
buds, forming alcoves all round the top and sides of the first one,
growing on to it. These again bud out, and you can thus easily
understand that, in this way, in time a good-sized leaf is formed.
Meanwhile the creatures also send forth new swimming cells, which
settle down near to begin new leaves, and thus a tuft is formed; and
long after the beings in earlier parts of the leaf have died and left
their alcoves empty, those round the margin are still alive and
spreading....
If you can trace the spore-cells and urns in the seaweeds, observe the
polyps in the Sertularia, and count the number of mouths on a branch
of my animal fringe (Sertularia tenella); if you make acquaintance
with the Thuricolla in its vase, and are fortunate enough to see one
divide in two; if you learn to know some of the beautiful forms of
diatoms, and can picture to yourself the life of the tiny inhabitants
of the Flustra; then you will have used your microscope with some
effect, and be prepared for an expedition to my pool, where we will go
together some day to seek new treasures.
[Illustration]
NOTES
AGASSIZ, J.L.R., naturalist, born in Switzerland, 1807; died,
Cambridge, Mass., 1873. In 1846 he came to America, after having
gained a high reputation in Europe, to deliver a course of lectures in
Boston "On the Plan of the Creation," and met with such success that
he spent the rest of his days there, declining an invitation to return
to his native country and to Paris. In 1848 he was elected to the
chair of Natural History at Harvard. In 1850-51 he went on an
expedition to the Florida Reefs. In 1858 he founded and organized the
Museum of Comparative Zoölogy at Cambridge--and, later on, went on his
important voyage to Brazil. In 1872 he founded and organized the
summer school of Natural History at Buzzard's Bay. He wrote "The
Fishes of Brazil," "A Study of Glaciers," "Natural History of the
Fresh Water Fishes of Central Europe," "Contributions to the Natural
History of the United States" (unfinished), and with his wife, "A
Journey in Brazil."
BALL, PROF. SIR R.S., English astronomer, born in Dublin, 1840. Was
appointed Lord Ross's astronomer in 1865. Professor of mathematics and
mechanics at the Royal Irish College of Science in 1873, and is now
astronomer royal for Ireland. He is the author of "The Story of the
Heavens," "Starland," etc., and is well known as a successful lecturer
on astronomical subjects in this country.
DARWIN, CHARLES R., English naturalist, born, 1809; died, 1882. He
first formulated what is known as the principle of Natural Selection.
In 1831 he went in the famous scientific voyage of the _Beagle_ as
naturalist, and afterwards published an account of it. He was one of
the most thorough, careful, and painstaking scientific men of this or
any age. He is the author of many famous books. "The Origin of
Species," "The Descent of Man," "Insectivorous Plants," "The Power of
Movement in Plants," "The Structure and Distribution of Coral Reefs,"
"Geological Observations on Volcanic Islands." "The Formation of
Vegetable Mould" was his last published work.
FLAMMARION, C., famous French astronomer, born, 1842. He has written
many popular works on astronomy, most of which have been translated
into English. "The Stars," "The World Before the Creation," "Uranus,"
"Comets," "Popular Astronomy," are among his best known.
HOLDEN, PROF. E.S., American astronomer, born at St. Louis, 1846.
Lieutenant engineers, U.S.A., 1870-73; professor mathematics, U.S.N.,
1873-81; director Washburn Observatory, 1881-85; president University
of California, 1883-88; director Lick Observatory, 1888-98. Is a
member of several learned societies of Europe. Is the author of a
"Life of William Herschel," "A Hand-book of the Lick Observatory,"
"Earth and Sky," "Primer of Heraldry," "Elementary Astronomy," "Family
of the Sun," "Essays in Astronomy," "Stories of the Great
Astronomers," etc.
HUXLEY, T.H., English biologist, born, 1825; died, 1895. Went on an
exploring expedition on the _Rattlesnake_, and devoted himself to the
study of marine life. For his scientific researches he received many
honors. His lectures were models of clearness, and he could simplify
the most difficult subjects. He strongly advocated Darwin's views and
evolutionist doctrines. His writings are numerous and many of them
technical. Among some of the most popular are "Man's Place in Nature,"
his "Lay Sermons," "Critiques and Addresses," "American Addresses,"
"Physiography," "Science and Culture," "Lessons in Elementary
Physiology," etc.
KINGSLEY, C., English clergyman and author, born, 1819; died, 1875.
Wrote "Westward, Ho!" which every boy should read, "Hypatia," "Alton
Locke," "Hereward the Wake," etc., and a charming book of travel,
entitled, "At Last." His "Water Babies" is exceedingly popular, and
his "Heroes" is a book much appreciated by the boys and girls alike.
PROCTOR, R.A., English astronomer, born, 1834; died, 1888. He was a
very popular writer, and lectured on astronomical subjects in this
country, and in England and her colonies. A memorial teaching
observatory is erected in his honor near San Diego, Cal. He was a man
of untiring industry, an athlete, a musician, and a chess-player. His
books are numerous. Among them are "Half Hours with the Telescope,"
"Other Worlds than Ours," "Light Science for Leisure Hours," "The
Expanse of Heaven," "The Moon," "The Borderland of Science," "Our
Place Among Infinites," "Myths and Marvels of Astronomy," "The
Universe of Suns," "Other Suns than Ours," etc.
SHALER, N.S., professor of geology at Harvard. Born Newport, Ky.,
1841. Served in the Union Army during the Civil War. Instructor
zoölogy, geology, and paleontology, Lawrence Scientific School, till
1887. Since then at Harvard. Is the author of "Kentucky a Pioneer
Commonwealth," "The Story of Our Continent," "The Interpretation of
Nature," "Feature of Coasts and Oceans," "Domesticated Animals," "The
Individual," "Study of Life and Death," etc.
THOMPSON, SIR C. WYVILLE, English zoölogist, born, 1830; died, 1882.
He conducted scientific dredging expeditions in the _Lightning_ and
_Porcupine_, 1868-69, and was the scientific head of the famous voyage
of 68,900 miles in the _Challenger_ for deep-sea explorations
(1872-76). His books are "The Depths of the Sea," and "The Voyage of
the Challenger."
TYNDALL, JOHN, English physicist, born, 1820. Began his original
researches in 1847, when teacher of physics in Queenwood College. He
and Professor Huxley visited the Alps together, and they wrote a work
on the structure and nature of glaciers. It is impossible to detail
the work he has done; but his inquiries and experiments in connection
with light, heat, sound, and electricity have all had practical
results. He is a popular lecturer, and devoted the proceeds of a
lecturing tour in this country to founding scholarships at Harvard and
Columbia Colleges, for students devoting themselves to original
research. Among his books are "Glaciers of the Alps," "Mountaineering,"
"Heat as a Mode of Motion," "On Radiation," "Hours of Exercise in the
Alps," "Fragments of Science," "The Floating Matter of the Air," and
volumes on Light, Sound, Electricity, and the forms of water.
WALLACE, A.R., English naturalist and traveller, born 1822; was
educated as land surveyor and architect, but afterwards devoted
himself entirely to Natural History. He explored the Valley of the
Amazon and Rio Negro, 1848-52, and travelled in the Malay Archipelago
and Papua, 1854-62, publishing the results of his explorations later
on. He also wrote "Contributions to the Theory of Natural Selection,"
"Miracles and Modern Spiritualism," "Geographical Distribution of
Animals," "Tropical Nature," "Island Life," etc.
GIBERNE, AGNES, English author--living. Began to write at seven years
old. Her first story for children was published when she was only
seventeen. Her stories for children have not been so popular as her
scientific writings, "Sun, Moon, and Stars," "The Starry Skies,"
"Among the Stars," "The Ocean of Air," "The World's Foundations,"
"Radiant Suns," etc.
WILSON, ANDREW, English physiologist and lecturer, born, 1852. Is the
author of "Studies on Life and Sense," "Leisure Time Studies,"
"Science Stories," "Chapters on Evolution," "Wild Animals," "Brain and
Nerve," etc., and is a constant contributor on scientific subjects to
the magazines and newspapers, contributing weekly "Science Jottings"
to the "Illustrated London News"
WONDERS OF EARTH, SEA, AND SKY
SUGGESTIONS FOR SUPPLEMENTARY READING
Wonder Stories of Science
D.N. BEACH
Wonders in Monsterland
EDWARD W.D. CUMING
Ocean Wonders
W.E. DAMON
Among the Stars
AGNES GIBERNE
The Scenery of the Heavens
JOHN ELLARD GORR
Coal and the Coal Miners
HOMER GREENE
Wonders of the Moon
A. GUILLEMIN
The Sea and Its Living Wonders.
G. HARTWIG
The Wonders of Plant Life Under the Microscope
SOPHIE B. HERRICK
Marvels of Animal Life
CHARLES F. HOLDER
Old Ocean
ERNEST INGERSOLL
Modern Seven Wonders of the World
C. KENT
Madam How and Lady Why
CHARLES KINGSLEY
Wonders of Optics
F. MARION
The Wonders of Science
HENRY MAYHEW
Wonders of Man and Nature
E. MENAULT
A Century of Electricity
T.C. MENDENHALL
The Orbs of Heaven
ORMSBY S. MITCHELL
Under Foot
LAURA D. NICHOLS
Myths and Marvels of Astronomy
R.A. PROCTOR
The Wonders of the World
CHARLES G. ROSENBERG
The Wonders of Nature
PROFESSOR RUDOLPH
Volcanoes of North America
ISRAEL COOK RUSSELL
Aspects of the Earth
N.S. SHALER
Wonders of the Bird World
R.B. SHARPE
The Wonders of Water
GASTON TISSANDIER
Total Eclipses of the Sun
MABEL L. TODD
Wonders of Insect Life
JOSEPH C. WILLET