Part 16

Trees change size from hour to hour. The circumference of a tree trunk gets bigger and smaller with unpredictable perversity. For light on this phenomenon the world is indebted to Dr. John A. Small of Rutgers University.

About a decade ago tree scientists were provided with an instrument which could measure continuously the radial growth of a tree with an accuracy of a thousandth of an inch. With such an instrument it seemed plausible that it would be possible to tell just how much a tree had grown in a single day and its rates of growth in different seasons. A lot of the conclusions reached in this connection must now be discarded. The circumference of a tree certainly changes but not in a straight line. It may be bigger one day, smaller the next.

Dr. Small’s experiments were carried out with the white ash. He found that circumference changes followed yearly, monthly and even daily rhythms but the changes in the same tree might vary by as much as 200 percent when measurements were made at different times. Daily variations have shown a tendency to reach maximum readings about 6:30 a.m. and sink to minimum in the late afternoon or early evening. Eccentric jumps and drops can be found almost any time.

_Underworld Cities_

Seventeen-year locusts build great subterranean “cities” during their long sojourn in the earth’s depths. The years underground are by no means a resting period—an episode of being buried alive. All the time the young locusts, in various metamorphoses, are busy building and eating. The eggs of the strange insects are laid during a few weeks late in summer inside twigs. From these eggs come minute nymphs, which at once make their way into the ground. There they shed their shells and grow rapidly. Their food is juice sucked from roots. They make successive mud dwellings attached to these roots. The largest observed in the eastern United States were eighteen inches below the surface. Each was a rough ball of earth about two inches long and three-fourths of an inch wide. The ball is lined on the inside by smooth mud and contains only one nymph. Every time an individual moults and grows larger it must make a new house.

When they emerge from the last of their feeding chambers, the locusts dig rapidly upward and construct a somewhat different type of dwelling some inches below the surface. These are two-chambered, with upper and lower rooms connected by tunnels five to ten inches long. These are so ingeniously constructed, according to Dr. E. A. Andrews of Johns Hopkins University, that they provide “the advantage of safety along with quick access to the surface when the proper time comes. In the shaft the nymph climbs close to the surface or falls rapidly to the bottom to escape attacks. The lining of the shaft is smooth mud a few millimeters thick. The shafts are by no means always straight or of uniform diameter, but may be sinuous and present swollen regions.” In one area examined he found at the topsoil was such a mass of small stones and roots that the insects must actually have cut their way through roots. Large obstacles often were avoided by a change in direction.

“The chief implements used in making cavities in the earth”, according to Dr. Andrews' report, “are the big first legs. Here, as in other legs, the end segment is used chiefly in walking and may be folded down when not needed. The second segment from the tip is used to pick off particles of earth. The third segment is the largest and, like a powerful thumb, acts with the opposing second segment as a forceps to pick up pellets of earth and small stones. The minute particles picked loose from the earth are raked together by the tip segment to make a pellet, which the forceps can carry or shove into the walls of the cavity. However, all parts of the body may come into use, for the hind legs and the abdomen may help shove earth aside and the head may carry earth plastered upon it. In vertical tunnels the animal braces its legs against the sides and, if disturbed, relaxes and drops down.”

The last dwelling is large enough for the nymph to turn around inside and usually has a flattened floor. The top comes quite close to the surface without actually breaking through, leaving only a few millimeters of earth through which the insect must dig when the transmutation to an adult locust takes place. Examination of many of these tubular dwellings shows that there are no interconnections between them. Each has its own individual exit and along its course avoids contact with other chambers, although they often are very close together. This last home of the locust, before it emerges from the everlasting darkness to the world of light and quick death which is its pre-ordained destiny, is not necessarily restricted to the earth but may be contained above the surface. Aerial extensions may, in fact, be abundant and are in the form of turrets, towers, cones, chimneys, huts and adobe houses. The walls are of dense mud, not natural soil. Externally they are made of tiny mud pellets, but lined internally with the same smooth layer found in the underground dwellings.

_Plants That Create Mirages_

An explorer in the desolate heights of the Santa Marta mountains in northeastern Colombia, fog-wrapped and 10,000 feet above sea level, may see a flock of sheep grazing placidly among rocks ahead of him. Then, looking the other way, he may see an assembly of cowled, robed priests, apparently in the midst of some weird ecclesiastical ceremony. But when he reaches the places where he thought he saw these things there are neither sheep nor priests. He finds instead two strange varieties of the aster family, both among the real curiosities of the plant kingdom.

The vegetable sheep are bushy plants which grow on nearly barren ground near the mountain tops. The individual plant consists of thickly branched stems, about the size of a human finger, bearing many layers of leaves covered with wool-like hairs. Sometimes these leaves are so thick that the point of a pencil cannot be thrust through them. Some of the plants may be as large as a living-room sofa.

The extreme compactness of these plants and their dense covering of hairs is an adaptation to the hostile conditions under which they must live. The habitat consists of rocky slopes where the hot, dry winds of summer and the snows, low temperature and violent gales of winter expose them to a perpetual alternation of desert and Arctic conditions.

In the same general region are the monk plants, belonging to a different family, who have responded in the same way to similar conditions. Seen from a distance on a mountainside, especially through a light fog, a patch of these plants looks decidedly like a congregation of several hundred priests.

The vegetable sheep also are found in New Zealand, but there are no known intermediaries between the closely similar species growing on opposite sides of the earth.

_The Octopus Worm: Evolution’s Mystery_

Worms that give birth to their own grandchildren, animals that have no digestive, muscular, nervous, glandular or excretory organs—such paradoxical creatures are the “dicyemid mosozoans”, tiny worms that live inside octopuses. These little worms are among the most curious living things in nature. It is quite uncertain whether they are a step upward in evolution from the single-celled protozoans or, like some other worms, a degenerate form of many-celled animals. It might be maintained that they represent a distinct branch of the animal kingdom.

The body of a dicyemid consists of a single cell, almost half an inch long, in the form of a hollow tube, surrounded by a layer of small cells. The immediate offspring are formed and, in some cases, live their entire lives and reproduce in turn, inside one of these “skin” cells. The grandchildren break through the body of the grandparent at any place they choose, apparently without causing any wound, and live for a short time as free-swimming animals until they find an octopus whose kidneys they can enter. Then the whole life cycle starts over again.

Apparently the infestation in no way injures the octopus and the worms are of no practical importance in the world. Each kind of octopus or squid in coastal areas has its own particular species of these parasites of which about 35 kinds are known.

The worm’s body contains no organs, tissues or glands in the usual sense of the word.

Before being born the larvae attain their full complement of body cells, are able to swim about, and have within them the germ cells that will give rise to the next generation. Birth is very simple. The larvae just push out, or are squeezed out, through the sides or ends of their parent at almost any point. The parent continues to develop and bear more larvae in the same manner. The number developing at any one time in the cell may range from one or two to 100 or more.

These larvae remain in the octopus as fully developed worms. But at certain times the germ cells develop into much smaller individuals, called infusorigens, hard to distinguish from large protozoa. These never leave the birth cell inside the parent, but produce germ cells of their own which develop into free-swimming creatures known as infusoriforms. These break away from the grandparent worm and from the octopus and become free-swimming animals. They are microscopic, less than a 300th of an inch long. They live from three days to a week. Here may be the borderline between single-celled and multi-celled animals—or perhaps the greatest degeneration in animal life.

_The Monster Bear of Kamchatka_

A gigantic black bear, probably the largest of flesh-eating animals, lives in the dense, hardly explored pine forests of southern Kamchatka. This creature still is unknown to science. So far as known it never has been seen by a white man. There is, however, considerable evidence for its existence presented in a report made several years ago by Dr. Sten Bergman of the State Museum of Natural History at Stockholm, who spent two years on the Kamchatka peninsula.

Photographs have been taken of this animal’s footprints in the snow. It leaves a track 15 inches long and ten inches wide. Dr. Bergman was shown a pelt of the giant bear. It was the largest bearskin he ever had seen, deep black in color, and covered with short hair in striking contrast to the long hair of other Kamchatkan bears. He also saw a gigantic bear skull, the teeth of which indicate that it belonged to a young individual.

Apparently this Kamchatkan black bear exceeds in size the Kodiak Island bear, which lives across Bering Strait and is the largest known flesh-eating mammal. The wildness of the country and its dense vegetation have protected the giant bear from naturalists and hunters. The whole land is a veritable paradise for bears who hide away in the dense thickets along the Kamchatkan rivers and subsist on the abundant salmon. They are so numerous that a native does not dare venture into the bush in summer without first shouting to let the bears know he is coming. They will keep out of a man’s way if they are warned, but are likely to attack him if surprised.

The great majority of the Kamchatkan bears are relatively small animals, comparable to those of northern Europe. Some are black, but the majority are yellowish-white or light brown. The giant animal may be an extreme variation of this race, or may represent an entirely different species. He naturally is the subject of much native legendary. Some stories have been interpreted as indicating that mammoths existed within the time of man in the northern wildernesses of both hemispheres, but such a giant bear would fit the descriptions as well as would a small elephant-like creature.

If it were not for the great numbers of smaller bears, man scarcely could subsist in this country. There are, for example, no roads through the desolate land between the villages. But all along the rivers and through the forests are well-marked paths made by the bears who seem to have an engineering instinct in choosing the most logical places for crossing morasses and mountains. These paths are about the only means of human communication and eventually, if the land ever is settled, will become the roads. In the same way elephant trails in Africa and India and bison trails in the United States became the hard-surfaced highways of today. Engineers hardly can improve on the instinct of the animals.

The small bears also play an important part in the domestic economy of the few inhabitants. The thick, warm pelt is used as a bed. Out of the skin the natives make reins, snowshoes and dog traces. The meat is much appreciated. In remoter parts of the country the linings of the intestines are used for windows instead of glass. Many of the native medicines are derived from the bear.

Both among the Kamchatka natives and the Ainu of northern Japan the animal is revered as a god—the concept being that the great celestial bear out of his benevolence to men provides creatures in his own form to furnish them food and clothing.

_Strange Denizens of the Deep_

Most fearsome of all sharks in appearance is Isistius braziliensis, found in the tropical Atlantic, Indian and Pacific oceans. It is a wine-brown colored creature with sharp teeth set in 20 rows which glow at night with an unearthly light.

“When the specimen, taken at night, was removed into a dark apartment it afforded a very extraordinary spectacle,” relates naturalist F. D. Bennett. “The entire inferior surface of the body and head emitted a vivid, greenish phosphorescent gleam, imparting to the creature, by its own light, a truly ghastly and terrible appearance. The luminous effect was constant and not perceptibly increased by agitation or friction.

“When the shark expired, which was not until it had been out of the water more than three hours, the luminous appearance faded entirely from the abdomen and more gradually from other parts, lingering longest around the jaws and on the fins. The only part of the under surface of the animal which was free from the luminosity was the black collar around the throat.”

One of the sea’s strangest denizens is the bramble shark. It is a shark of medium size whose body is almost completely covered with short, sharp spines. This fantastic creature apparently is widely distributed through the Atlantic and Pacific, but it is not likely to come into the hands of collectors. Its general flabbiness stamps it as a deep water animal and the anomalous position of its fins indicates that it is a weak swimmer. Its spiny armament obviously is designed for protection.

Entirely harmless, it is probable, are the giant “basking sharks”, which sometimes reach a length of forty feet. When encountered they rarely, if ever, try to defend themselves but attempt to escape by swimming slowly away. Stories that this monster dives when harpooned and sometimes will drag a small boat with its crew to the bottom now are discredited. Although it reigns as a monster among sharks it is not actually as dangerous as the common dogfish shark.

Perhaps the most dangerous are the so-called “carchaodons”, found in most warm seas although nowhere in abundance. They are among the most powerful and voracious of fishes, but still far less frightful than their fossil ancestors. The latter were the largest of all fishes; they were probably twice the length of the largest basking or whale sharks. Some were more than 88 feet long.

_Communism Among the Bees_

Honey bees have achieved an ideal communistic state. All the 50,000 or more members of a family—all progeny of a single queen—share and share alike. A single sample of sugar or nectar brought into the hive by a forager is participated in by all the bees. Thus all get essentially the same diet. They all acquire a common odor by which they can recognize each other. This odor constitutes a “scent language” which is the basis of the extremely complex bee social life.

These observations, based on experiments with radioactive sugar, are reported by Dr. Roland Ribbands of Cambridge University. In one of these experiments, Dr. Ribbands reports, “a marked bee is trained to collect sugar solution from a small glass tube, and when radioactive sugar is substituted the bee continues to collect the radioactive syrup quite happily. It returns to the hive and what happens to the labeled sugar can be followed quite easily. Every bee that receives some can be spotted by means of a Geiger counter. By collecting a sample of bees from the hive, one can discover what proportion of the colony has acquired some of the sugar. One stomachful can be shared among almost all the bees of a large colony. The experiments indicate that this sharing is a random affair. The sugar is passed on irrespective of the recipient’s age or occupation.”

Building up of a colony odor through universal sharing of the food supply enables members of the colony to recognize each other. This apparently makes little difference when food is abundant but becomes of great importance in periods of scarcity.

“At those times of the year,” Dr. Ribbands points out, “when there are insufficient flowers to provide all the bees with food, they often try to steal the honey stored in other colonies. Then the ability to recognize hive mates and to distinguish them from other honey bees will enable a colony to defend itself against attempts at robbery.

“However, the honey bee community does not defend itself by attacking every invader that does not possess the community odor. Strangers are attacked only under certain circumstances. In order to investigate these circumstances two colonies of differently colored bees were placed close together, with their entrances only two inches apart, so that bees often went into the wrong colony by mistake. When good supplies of nectar were available, the intruders were allowed to enter the strange colony, but when nectar was short the strangers were attacked and thrown out, often being killed in the process.

“Production of a common and distinctive odor which enables the colony to defend itself against members of other communities is a very important consequence of the habit of food-sharing. Better sharing means better defense and so a greater likelihood that the community will be able to survive and perpetuate its kind. The habit plays the key role in the system of communication which enables the new forager to learn about suitable crops, in that the new recruit always receives a sample of the crop the colony is working. The first flight becomes a search for a crop with a similar scent. The habit enables the worker bees in a colony to be apprised of the presence of their queen. A substance derived from her body is conveyed from bee to bee in the shared food, and in the event of any deficiency in the substance they take steps to rear another queen.

“In addition, it probably helps to ensure an effective division of labor in the colony, which has to be so integrated that a suitable proportion of the worker population carries out each of the various tasks necessary for maintenance of the colony.”

_Candles on Bushes_

In parts of Colombia candles in the form of white, wax-like berries grow on bushes. These berries produce oil of such excellent quality that it is used almost exclusively for altar lamps in Catholic churches throughout the country.

The berries grow abundantly on a jungle plant with leaves like those of rhubarb. In only one part of the country is the plant cultivated. It is a crop of the semi-hostile Paez Indians. Harvesting is somewhat difficult because the oil-containing white seed is inside a burred coat. This must be removed and the seeds placed in hot water. The oil rises to the surface where it can be skimmed off.

When it is desired to make candles a dozen or more berries are strung on a stick. Such a candle gives off a beautiful, soft light.

_The Desert Rat Manufactures Water_

All animals require water in their bodies, but some can get it without actually drinking. The desert rat which lives among the bare sand dunes of California’s Death Valley, can get along indefinitely without water and with only dry barley seeds for food. In spite of this about 65 percent of its body weight is water. Most of the water is actually made in the animal’s body. The rat’s digestive processes extract the hydrogen contained in the barley seeds and combine it with oxygen in the air to create water.

_The Caste System of the Termite_

The oldest civilization on earth is that of the termites. The super-organization which these blind white creatures of the dark have achieved precedes by thousands of millenia those of the ants and the bees. Termites have a far longer history on earth, being considered modifications of the ancient cockroaches who were among the first insects to leave any traces of their existence on land. Cockroaches swarmed in the club moss forests at least 250,000,000 years ago. The termite order is at least 30 million years old; some of its most primitive forms still are alive.

In most of the approximately 2,000 species of termites which have been identified all over the world there are five castes, apparently determined from birth although not so rigidly as among ants. First are the winged males and females with large brains and eyes and hard, dark shells. These depart in great swarms from the ancestral nest once or twice a year, usually in spring and fall. They are feeble flyers and depend chiefly on transportation by air currents. The majority are eaten by birds. The few surviving pairs from such a flight excavate cells in the earth or in wood and start new colonies. There is at least one king and one queen in each cell. Sometimes there are two or more pair. They remain partners for life. Both are imprisoned within the cell. Before entering it they slough off their wings, which henceforth would be worthless.

The termite queen becomes an inert, egg-laying machine, sometimes the size of a small potato. In some species she lays an average of sixty eggs a minute, or 80,000 a day. She may live as long as ten years. Thus each queen ideally produces about a half billion new individuals. Her bulk increases as much as 50-fold in adult life—about the most phenomenal growth in nature.

The second termite caste, for which there is no parallel among the ants, consists of both males and females with only rudiments of wings, less fully developed reproductive organs, and somewhat smaller eyes and brains. They presumably serve only as an auxiliary royalty, functioning in case the true rulers die. Apparently by some subtle alchemy known only to termites they can be transformed into fully functioning sexual individuals if an emergency arises.

A third caste is made up of smaller insects with extremely minute eyes and brains and barely discernible reproductive organs. Below them come the entirely unpigmented, soft-bodied workers with still smaller eyes and brains—usually, in fact, with no eyes at all. These still are potentially males and females, in distinction to any society where all workers and soldiers are female. Lowest in the scale are the big-headed, blind soldiers, also of both sexes, with barely a trace of brain.

Relative numbers in these castes differ from species to species. An analysis of an Australian termite colony accounted for 1,560,500 workers, 200,000 soldiers, and 44,000 potentially reproductive individuals.

_The Shark That Stands Upright_