undifferentiated kind of life. The cells had no specialized function.
In the actual plant they were kept in order by the rest of the plant
cell community, which has no use for cells with no job to do. Once
in the nutrient solution, however, they were free of all inhibiting
influences. They were not, and never became, wood cells, bark cells,
pith cells, leaf cells or any of the other numerous, specialized kinds
of cells which make up the plant world. They were something very close
to the primaeval plant cells from which, in the course of a couple
of billion years, all the others have been derived. Very early these
unit structures of life learned that they must stick together and do
specialized jobs for each other under the actual conditions of nature.
Out of these combinations of specialists has arisen all the magnificent
structure of the living world.
But the experimental cells at the Rockefeller Institution had nothing
to do except eat and multiply. Each of them was potentially immortal.
It did not die but renewed its youth when it had reached its growth by
becoming two baby cells. That is how life might have developed from
the beginning except for the fact that a cell must eat to live and
ordinarily does not have any accommodating scientist to feed it.
_Birds That Duel_
Birds that hold fencing tournaments are the big-billed toucans of Barro
Colorado Island, the Smithsonian Institution’s tropical preserve in
Gatun Lake, Panama Canal Zone.
They fence with their formidable beaks but seem careful not to hurt one
another. One scientist who studied Barro Colorado’s bird life described
the birds as follows: “I saw fourteen toucans scattered about in a big
leafless tree in the center of the jungle. Two appeared to be fencing.
They stood in one spot and fenced with their bills for a half minute
or so, rested, and were at it again. Presently they flew off into the
forest and then I noticed two others that had now begun to fence. Then
one of these flew away, and the remaining one picked a new opponent and
fell to fencing again.... They did not move about much while fencing,
although sometimes one climbed above the other as though to gain an
advantage. They fenced against each other’s beaks and never seemed to
strike at the body. There was a fairly rapid give and take...the
bills clattering loudly against each other.”
These fencing toucans are among the more conspicuous birds of the
island, particularly because of their call—a shrill, froglike “cree,”
which is repeated over and over again and can be heard half a mile
away. The call is most frequent in the morning and late in the
afternoon, but it stops abruptly at sunset.
_Brakes on Plant Life_
There is a “brake” on plant development—perhaps one of nature’s most
fundamental controls over surging life. It is a relatively narrow
band of light on the edge of the invisible infrared in the solar
spectrum. Plant life, and through plants all life, is tied intimately
to certain solar wave bands. It has long been recognized that the
cornerstone of all life on earth is the process of photosynthesis
by which plants, through energy provided by sunlight, are able to
synthesize carbohydrates from water and carbon dioxide taken from the
air. Animals eat these carbohydrates, the basic food. Other animals eat
the carbohydrate eaters, and thus the chain extends from the simplest
organisms to man.
But without some other process the carbohydrates might be a formless
mass. The second process is that which shapes a plant and controls
development of stems, leaves, and blossoms. This may be a light effect
second in importance only to photosynthesis itself. It requires
very little solar energy. Smithsonian Institution experiments have
demonstrated that the control is exercised by red light with a maximum
of efficiency at wavelengths around 660 millimicrons—or millionths of
millimeters. It has been demonstrated, however, that this formative
action can be blocked effectively by irradiation with wavelengths in
the far red. The greatest effect is at wavelengths between 710 and 730
millimicrons.
The “brake” is not applied immediately. The maximum efficiency of
the far red energy occurs a little more than an hour after the plant
is exposed to the formative wavelengths. The implication is that
the action interferes with the development process by acting on
some product the formation of which is initiated by the shorter red
wavelengths. The experiments have been carried out with seedlings of
beans. In other experiments it has been found that damage to plants
from X-ray exposure—insofar as this results in breaking the bundles of
genes, or units of heredity—can be increased from 30 to 50 percent by
previous exposure to about the same wave band of far red light that
reverses the formative process. On the other hand, the increase in
damage is nullified if the X-ray exposure is followed by exposure to
the red wave band.
Breaking of the chromosomes, or strings of genes, is one of the first
evidences of damage to living organisms by exposure to ionizing
radiation. This breaking is responsible for some of the adverse
hereditary effects concerning which there has been a great deal of
discussion because of possible effects of the atomic bomb fall-out.
The experiments were carried out with pollen of flowers and root tips
of beans where results are relatively easy to determine.
_Snails Are the Flowers of the Sea_
There are more than 80,000 kinds of snails in the world. They swim,
jump, crawl, burrow, live at the bottom of the sea and in the tops of
trees. They range in size from the horse conch of Florida, two feet
long, to animals hardly the size of a grain of sugar. About half of all
species live in the seas.
Most are bottom dwellers, unable to swim, but several spend their lives
on the surface. One, the purple janthina, floats upside down on a raft
of air bubbles trapped in a special kind of mucous which it secretes.
Others live permanently attached to sea weeds. Most abundant of the
sea snails probably are the pterepods, or sea butterflies, which live
several feet below the surface in daylight but come to the top in
countless hordes at night. In some places the sea bottom is littered
many feet deep with their shells, of which there is almost constant
rain as the animals die.
Loveliest flowers of the sea are the nudibranchs. Seldom has nature
produced in either plants or animals such elaborate combinations of
brilliant colors and decorative appendages as in the bodies of these
shell-less ocean snails. Although there are more than 2,000 species,
they are among the least known of all sea creatures. One reason for
this is that most of them are quite small, ranging from a fourth to
half an inch in length. Their coloring hardly can be appreciated except
under some magnification.
Nowhere are they very abundant. Their habitats vary from close inshore
to deep water, but they are most likely to be seen in pools left
among shore rocks by receding tides. Their extremely elaborate color
patterns may be protective, to some extent. It is known that certain
species have the ability to change colors in response to changes in
their environment. They become bright red, for example, when living
in association with a red sponge. Even more decorative than the color
patterns are the appendages, extensions of the skin and sometimes of
the digestive tract, which take the forms of delicately modelled,
almost microscopic plants.
All these nudibranchs are flesh-eating creatures feeding chiefly on sea
anemones found on the sea bottom. Most of the anemones are equipped
with thousands of so-called nematocysts or stinging organs. These are
microscopic, ball-shaped structures filled with a virulent poison. The
same mechanism is best known in sea nettles. As soon as a nematocyst is
exposed to any tension it explodes, releasing this poison.
The little sea snails have evolved the ability to swallow the poison
balls without exploding them. They pass into the digestive tract, but
are not digested. In some way the nematocysts find their way through
certain of the appendages growing out of the digestive organs to the
outside of the body. There they are retained, and serve the sea snail
in the same way they served the sea anemone. The little creature
becomes quite dangerous to any of its natural enemies.
Among the most enthusiastic nudibranch collectors is the Emperor of
Japan, who has discovered and described several new species. Some of
his publications about them have been illustrated by leading Japanese
artists and show the unearthly beauty of the creatures to the best
advantage.
_The Brutal South Pole Birds_
The southernmost birds on earth—the only higher animal except man and
his dogs that go close to the South Pole—are the Antarctic skuas.
They are fierce, brutal little killers. Dwellers in the earth’s most
inhospitable habitat, they have been able to survive largely because of
their extreme rapaciousness.
All other Antarctic birds, such as the penguins, stay close to the
shore of the desolate continent. The skua has been seen at least 300
miles inland, and occasionally may fly across the pole itself.
These birds arrive on the coast of Antarctica about the middle of
October, the beginning of the southern summer, after spending the
winter north of the circle. Their arrival is timed to coincide with
the egg-laying of the Adelie penguins. The skua’s chief food consists
of penguin eggs and chicks which it devours by the hundreds. Scores
of half-eaten, trampled bodies of young penguins always can be found
during the hatching season near the sites of penguin rookeries. The
skua is hardly a match for the parent birds but is expert in separating
chicks from the brood and killing them when they have no protection. It
is a creature of relatively enormous strength and endurance and flies
long distances carrying chunks of meat bigger than itself. It also is
an extremely noisy, quarrelsome creature—an outstanding example of the
philosophy of every individual for itself. There is no brooding of
chicks nor protecting them from the elements. The parents hardly bother
to feed them.
Little skuas, it is reported, come out of the eggs fighting. Usually
there are two eggs to a nest. One chick probably is a trifle weaker
than the other. In a short time it is driven from the nest, killed and
eaten by its rapacious brother or sister. It may even become the prey
of its own hungry parents. Skuas also have the habit of eating their
own eggs. This keeps the population within the limits of the food
supply.
_Silk-Bearded Clams_
Jason’s golden fleece may have been woven from the beard of a
silk-bearded clam. The same sort of cloth, in fact, still is produced on
a small scale in Italy, chiefly for the tourist trade. A silk glove of
modern manufacture now is in the Smithsonian collections.
The clam is a giant Mediterranean species, the pinna marina. Its shell
reaches a maximum length of about three feet, but the average is less
than half this. From a gland in its “foot” it secretes milk-like
strands with which it attaches itself to the sea bottom. These strands
are as much as a foot long.
The silk is of exceptionally fine quality—at least it was so regarded
by the Arabs who maintained centers for manufacture of the cloth in
Spain, Italy and North Africa. Says one Arab author: “At a certain time
of the year an animal comes forth from the sea and rubs itself on the
stones of the seashore. A down soft as silk with a golden color falls
off it. It is fine and small and garments are woven from it which take
on different colors during the day. The Umayyad kings (of Spain) used
to put restrictions upon it so that it was only exported secretly. The
price of a garment is more than 100 dinars, on account of its fineness
and beauty.”
The value of a dinar—the gold coin of the Moslem world—is difficult to
calculate in any present coinage, but it was at least the equivalent of
a dollar.
Says another Arab writer: “I have seen how it is gathered. Divers dive
into the sea and bring out tubers like onions with a kind of neck which
has hairs on the upper part. The tubers like onions burst and let
forth hairs which are combed and become like wool. They spin it and
make a woof of it so as to pass a warp of silk through it. The most
magnificent royal garments of Tunis are made of it.”
Gigantic clams, nearly five feet long and weighing more than 400
pounds, who raise crops of microscopic plants for their own sustenance
are among nature’s fantasies found on Australia’s Great Barrier Reef.
These molluscan titans have formed a curious partnership with the
zooxanthellae, a family of microscopic algae. The plants live as
parasites in the blood cells of the inner lobe of the clam’s mantle.
Upon this mantle is a lens-like structure which looks like an eye.
These mollusks, however, are blind as any other clams and the eye-like
protuberances, it has been determined, are only windows by which light
is admitted to the parasitic algae within the blood cells. The surplus
of algae is carried by the blood stream to the clam’s digestive organs
where it serves as food.
Another giant clam, the tridacna of East Indian seas, may weigh up to
600 pounds. The monsters constitute a peril for divers who unwittingly
step inside the open valves. These snap shut, imprisoning the diver’s
foot and, unless he can get help, he is held in the trap and drowned.
_Pearls Grow in Brooks_
Excellent pearls occur occasionally in fresh water clams. A pearl of
perfect form and pure color was found in such a clam taken from a brook
near Paterson, New Jersey, in 1857. It sold at Tiffany’s for $1,000 and
shortly afterwards was resold in Paris for $2,200. This started pearl
hunts in brooks all over the country.
On the arrival of Europeans in Florida, Louisiana and Virginia,
fabulous legends were circulated about the enormous treasures to be
obtained by plundering Indian graves. A contemporary chronicler of the
audacious DeSoto expedition, reported that the conquistadore got 350
pounds of fine pearls at the Creek town of Cofitachique on the Savannah
River.
A member of the first Virginia colony “gathered together from among the
savage people about five thousande; of which number he chose so many
as mayd a fayre chain; which for their likenesse and uniformitie in
roundnesse, orietnesse and pidenesse, of many excellente colours with
equalities in greatnesse were verie fayre and rare.”
The supply, however, was quite limited. Indian pearls were the subject
of a special study by the late Dr. William H. Holmes. “The majority
of those obtained,” he reported, “were ruined as jewels by the heat
employed in opening the shellfish from which they were abstracted. Many
of the larger specimens probably were not real pearls but polished
beads cut from the nacre of sea shells and quite worthless as gems.
It has been found that the real pearls were obtained from bivalve
shells—from the oyster along the sea shore and in tidewater inlets and
from the mussel on the shores of lakes and rivers.
“But the very general use of pearls by the pre-Columbian natives is
amply attested. More than 60,000, nearly two pecks, were obtained,
drilled and undrilled, from a single burial mound near Madisonville,
Ohio.”
_Grasshopper-Infested Glaciers_
Among America’s natural curiosities are “grasshopper glaciers.” These
are great masses of glacial ice containing layers of imbedded, frozen
grasshoppers. Such layers are probably remnants of vast migrations
which have taken place at irregular intervals over several centuries.
Great hordes of the insects either flew over the glacier or were
carried there by winds, and while there sudden snow storms or cold air
rising from the ice field caused them to drop. They were imbedded so
quickly in the falling snow, which later became ice, that they have
remained perfectly preserved for centuries. The most notable of these
glaciers is in the Beartooth mountains of Montana. Others have been
reported from the high mountains of Africa.
_Monster Clams of Polynesia_
Largest of clams and largest of all shellfish is a native of Polynesian
seas. The two halves may weigh as much as 500 pounds. The flesh is
eaten raw by natives. The interior of the shell is like polished
marble. Such shells frequently were used as founts for holy water in
European churches. A particularly large one attracted much attention in
the Church of St. Sulpice in Paris. Such clams are found at depths up
to 17 fathoms. They fasten themselves to rocks by a process so tough
that it can only be severed with an axe.
_Corals Combine Plants and Animal Life_
A coral reef is a gigantic “plant-animal.” It is a community of
countless billions of plants and countless billions of animals which
act as a single organism, like the countless millions of specialized
cells that make up the body of a man or a mouse. It is probably the
most efficient of all earthly creatures. It is self-sufficient,
creating its own constant food supply. It is essentially immortal. It
is hungry like an animal. It is motionless like a plant. It is both and
combines the attributes of both. It is the largest and most enduring of
all creatures of land or sea.
The animals are coral polyps. They are tiny, wormlike organisms with
mouths surrounded by constantly probing tentacles. They are rapacious
and insatiable. They are essentially voraciously hungry stomachs,
bloodless, brainless, sightless, heartless. The polyps are close to
the bottom of animal life, vaguely related to the white, stinging
sea nettles which are the scourges of summer beaches. These little
creatures extract lime from sea water and secrete for themselves
limestone “houses,” the “bones” of the superorganism. Out of these they
have built up islands and almost subcontinents. Sharing their limestone
cells are quite unrelated organisms, single-celled plants or algae.
These plants possess the green of grass and forests, whose molecules
create out of carbon dioxide and water through the energy of captured
sunlight starches and sugars which are the fuel of animal life. This
process of photosynthesis is the cornerstone of all life on earth.
Thus the plants feed their partner animals. The excretion of the
animals, in turn, provides the essential fertilizer of the plants.
Considering the coral reef as a superorganism one might almost say that
it eats itself but loses nothing in the process. A reef, considered as
a superorganism, represents about the last word in nature’s efficiency.
It has been found, for example, that one acre of coral reef produces
about 74,000 pounds of sugar a year, a record barely reached by man on
his most efficiently managed plantations. All this sugar is devoured
by the polyps. Apparently the fertility of the surrounding sea makes
little difference. Coral reefs flourish in parts of the ocean that are
essentially deserts.
A marine biological laboratory has been established by the U. S.
Atomic Energy Commission, to study effects of the radiation from
nuclear explosions on plant-animal populations. The first requirement
has been to determine the natural condition of the organisms before
being subjected to this radiation. Then whatever changes take place
with subsequent bomb tests can be noted. The work has been undertaken
by biologists of Duke University and the University of Georgia.
Such a life community, both a vast assembly of organisms and a sort
of superorganism, is an almost perfect subject for the required
observations. The first job, according to the commission report, has
been to measure the “basal metabolism” of the reef as a whole.
Admittedly the conception of a reef as a sort of superorganism is
somewhat mystical. The Duke and University of Georgia biologists do not
maintain that there is any consciousness of constituting a whole on
the part of the individual organisms. It is likely that they have no
consciousness of anything. The outstanding fact is that they behave so
much like a whole.
A reef is an outstanding example of the two major divisions of
life, plant and animal, working in perfect co-operation. The actual
co-operation of plant and animal in an integrated organism is not
unique for the coral reefs. Something of the sort occurs in certain sea
worms, near the bottom of the worm family, that grow green algae in
their blood streams. These worms make some of the beaches of Normandy
grass-green in summer. The algae are necessary for their existence.
There may be a few other examples throughout the animal kingdom.
_The First Engineers—Termites_
Termite civilization probably has reached its greatest heights in
architecture and engineering. Australian mounds, built by workers out
of earth particles cemented together by a salivary gland secretion,
are steeple-shaped, as much as twenty feet high, and with bases twelve
feet in diameter. Hundreds of such structures may be scattered over
a few acres. Such an assemblage looks like a large native village,
although architecturally the structures are far beyond the abilities
of primitive man. The common type consists of a solid, hard outer
wall which has the strength of superfine concrete. It is almost
impossible to break through this material. Immediately inside are
numerous thin-walled passages and galleries. Below these, at the ground
level and about in the center, are the quarters of king and queen
and the nursery. From the mound, passages for the food foragers lead
in all directions through the soil. A mound two feet high will house
approximately two million individuals.
Long before architects, termites developed the art of air conditioning.
Proper humidity inside the nest is essential to the existence of the
soft-bodied workers. The majority of species, however, are found in
latitudes with long, dry seasons. To meet such conditions the insects
achieved humidity control in various ways still not understood. Notable
are the structures of the Australian compass termites who erect
dwellings eight to twelve feet high with flattened sides. The broad
ends always point east and west, the narrow ends north and south. These
nests are strong enough to support the stamping of wild bulls. A group
of them looks like a particularly well-constructed native village, or
the site of some extinct human civilization. Apparently the precise
orientation of the nests is associated with prevailing winds and in
some way contributes to maintaining a constant humidity.
The blind creatures seem to have developed special sense organs,
unknown to man and probably unique in the animal kingdom. One of these
is reportedly a brain barometer which is extremely sensitive to slight
humidity changes. Both soldiers and workers respond with military
precision to any threat to their neighbors. This believed due to an
extreme sensitivity to vibration.
Few varieties of termites can endure sunshine. Some construct paperlike
umbrellas which they carry with them when they come above ground. One
species on Barro Colorado island in the Panama Canal Zone which attacks
live trees first builds a thin earth crust around the trunk, seven to
eight feet from the earth. Beneath this crust they seek out weak spots
in wood which enable them to penetrate into the heart of the tree.
Termite armies, in distinction from those of ants, serve only as
defensive forces. There are two kinds of soldiers. Some are equipped
with enormous jaws with which to rend the enemy. These are so tenacious
that when the body is torn away from the prey the mandibles remain in
place. Others are the bayonet men and chemical warfare troops. These
fighters have a protrusion on the front of the head which looks like a
long nose but which actually has developed from a primitive eye.