This edited article about chalk originally appeared in Look and Learn issue number 703 published on 5 July 1975.

Bleriot crosses the famous challk-white cliffs of Dover

If you look at a tiny fragment of blackboard chalk through a fairly powerful microscope, a fantastic world is opened up before your eyes.

Each speck of chalk is seen to have a most unusual shape: here is a tiny white star, there is a small sphere covered with minute holes, there again is a minute and delicate sea shell.

All these white stars and hollow globes are in fact the skeletons of microscopic sea creatures that lived in the sea many millions of years ago.

In their living state most of these animals looked like tiny blobs of jelly less than a hundredth of an inch across. Through the holes in some of the skeletons thin jelly-like tentacles projected out into the surrounding sea water, intertwining to form tiny nets to collect food.

Most of the star-shaped and sharp spiky skeletons are the skeletons of tiny sponges.

Mixed with all these strange skeletons we can also see crushed fragments which are the powdered remains of skeletons of other living creatures, such as sea-urchins.

When all these microscopic and primitive living creatures died their skeletons slowly drifted down to the sea bed, and formed a layer of creamy mud or “ooze.”

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This edited article about longevity in nature originally appeared in Look and Learn issue number 700 published on 14 June 1975.

Giant tortoise

A cone fell from a tree in Nevada, U.S.A. nearly five thousand years ago, took root and began to grow. Today, it has developed into a magnificent bristlecone pine tree and is the oldest thing alive.

Scientists dated it in the early sixties, probably by cutting a core through to the heart of the trunk and counting the rings revealed in this.

When a tree is cut down, the concentric rings across the trunk reveal the age of the tree, each ring representing one year’s growth. One bristlecone pine that had been felled was found to have five thousand rings, showing that it had begun growing at about the time the ancient Egyptians started to build their pyramids.

The surviving bristlecone pine, however, sprouted into life when the pyramids were already desert land marks 4,900 years ago. It is even older than the giant sequoia, known as the California big tree, which has a life span of between 3,500 and 4,000 years.

Compared to these, longevity in the animal kingdom is an insignificant thing. No creature’s average age is longer than that of Man’s. Few people live beyond the age of 110, although the average age is nearer seventy. Man’s closest rival is the tortoise, which holds the record for long life among the vertebrates. A common box tortoise has lived to become 138 and a European pond tortoise more than 120.

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This edited article about nature’s smallest animals and plants originally appeared in Look and Learn issue number 699 published on 7 June 1975.

Pygmy shrews

Our smallest native bird is the Goldcrest, but this is a giant compared with the world’s smallest bird the tiny Bee Humming Bird, found in Cuba and Ecuador. It gets its name because it is no bigger than a large bumble bee.

Its wings beat so fast that they are just a blur when it hovers in front of a tropical flower, its long beak dipping into the nectar in quest of nourishment. The adult females are slightly larger than the males.

Our smallest animal is the Pygmy Shrew, at two and one quarter inches, (57 mm), slightly smaller than the long-tailed Harvest Mouse. Even smaller is the Etruscan Shrew with a body length of only 1 and a half inches (38 mm) and reputed to be the smallest animal in the whole world.

Apart from animals, there are also a great number of microscopic insects. Some of these are so minute that they are scarcely visible to the naked eye.

The Dwarf Beetle, for instance, is small enough to pass through the eye of a small needle. The Small Blue Butterfly, less than 1 and a quarter inches (about 25 mm), across the wings, is the smallest British butterfly.

Unlike most of its kindred, it is only on the wing during the months of May and June.

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This edited article about size in nature originally appeared in Look and Learn issue number 698 published on 31 May 1975.

A Giant Squid

The Blue Whale is not only the largest animal living in the world today but it is the largest creature that ever lived on this planet and that includes any of the prehistoric monsters, such as the largest of the dinosaurs.

It grows up to a hundred feet long and can weigh as much as 135 tons. This is approximately the weight of 30 elephants.

These immense mammals are still hunted today, although their killing is now severely controlled. Many people believe that sighting of these huge whales gave rise to the age-old legend of sea monsters which could swallow up a ship in a single gulp.

Another giant of the deep is the Giant Squid, the largest of the molluscs. It lives at depths of 1,500 feet or more and grows up to nearly 60 feet long.

They possess ten arms and some varieties are known to be excellent swimmers; others seem just to be content to drift with the oceanic tides.

The largest living trees in the world are undoubtedly the Sequoias of California. The largest towers 368 feet into the air. It is taller than St. Paul’s Cathedral and has been estimated to weigh as much as 11,000 tons.

The “General Sherman” tree in Sequoia National Park stands only 272 feet high, but in total bulk, it exceeds any others. An age estimate which is based on ring counts, has put some of these trees at 3,000 years old.

The heaviest flying bird is the Mute Swan, although the South American Condor has the largest wing span.

The biggest bird of all is the African Ostrich. It stands 9 feet high and although it is too heavy to fly, it can run at nearly the speed of a racehorse, its short wings helping to balance it when running.

It can outdistance even the fleet antelope over sandy plains and open country and has been timed at a speed of nearly 40 miles per hour.

Among insects, the Goliath Beetle found in New Guinea, is over 3 inches long and is the largest of the world’s beetles.

The Hercules Moth, a native of Australia, is our biggest moth and boasts a wingspan of 9 inches.

The heaviest reptile known is the Leatherback Turtle. This is 8 feet long and could weigh half a ton.

The longest reptile of which there is any record, is the Anaconda Water Snake of South America, specimens of which have exceeded thirty feet.

This edited article about chocolate originally appeared in Look and Learn issue number 697 published on 24 May 1975.

Montezuma, the Aztec emperor, liked drinking cocoa

The Aztecs liked drinking cocoa almost as much as they enjoyed a good fight. Their last emperor, Montezuma, used to get through fifty golden cups every day, as Hernando Cortez and his band of Spanish adventurers noted, after they had invaded Mexico in 1519 and conquered the remarkable Aztecs.

It was certainly a better habit than tearing out human hearts as a sacrifice to the gods to ensure that the sun came up each day, another local custom.

Not that Cortez and his men discovered the humble cocoa bean, for, a quarter of a century earlier, Christopher Columbus had shipped a number of beans back to Europe. But the story of chocolate really begins with Cortez and his daring band of adventurers.

The Aztecs believed that their gods had provided them with cocoa trees, and they made chocolate from crushed cocoa beans, corn and water, and proceeded to spice it with pepper. This was too much for the Spaniards. But one of them had the bright idea of putting sugar into the brew, and it rapidly became so popular that women had steaming cups of it brought into church to sustain them during the sermon.

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This edited article about the Mutiny on the Bounty originally appeared in Look and Learn issue number 690 published on 5 April 1975.

Mutineers from the Bounty land on Pitcairn Island by Severino Baraldi

Mutiny on the Bounty . . . most of us have seen the film, most of us know the story of the savage and hasty-tempered Captain Bligh, who ruled his officers and men with such brutal discipline that finally many of them revolted and put him over the side of the ship in a small boat with eighteen men who remained loyal to him.

We know how, with superlative seamanship, Bligh navigated his tiny boat over 3,600 odd miles of the Southern seas, until, finally, he and his small party came to the safety of the island of Timor, part of the collection of islands that was then called the East Indies, and is now Indonesia.

We know that Captain Bligh eventually returned to England, that some of the mutineers were captured and hanged, that others were drowned at sea, that one small party sailed on to found a community on Pitcairn Island in the middle of the Pacific Ocean, and that their descendants are there to this day.

The story of the mutiny on the Bounty must be one of the best-known in British naval history. Not so well known is that the whole tragic affair began in the peaceful setting of the Royal Botanical Gardens at Kew, near London.

Two plant experts from Kew were on the ship. The object of the voyage was to collect breadfruit trees from Tahiti in the Southern Pacific and carry them across the seas to be replanted in the West Indies.

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This edited article about vitamins originally appeared in Look and Learn issue number 690 published on 5 April 1975.

A poster from the 1940s promoting healthy food consumption

Doctors were puzzled. In Britain’s smoky industrial cities, children were suffering from a disease which made them very ill and left them with bent bones.

But in the fishing ports, the youngsters seemed miraculously free from this ailment. What was the reason? In time, the doctors found the answer.

The fishermen’s children were eating bread dipped in fish oil, and it was the oil which was keeping them free from the dreadful illness, called rickets, which was spoiling the health of the city children.

Rickets is caused by a lack of calcium which is necessary for the building of strong bones. This cannot be obtained unless there is vitamin D in our food. Fish oil is rich in vitamin D, and that is why the fishermen’s children who ate it were fit and the city children, who were denied it, were sickly.

If we eat a balanced diet, we will get all the things we need to be healthy, including all the substances called vitamins, from the Latin word vita for “life”. They are tiny chemical compounds and were discovered in 1911 by Casimir Funk, a Polish scientist.

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This edited article about Louis Pasteur originally appeared in Look and Learn issue number 689 published on 29 March 1975.

Observing inherited characteristics of plant life led to Mendel’s Laws by L R Brightwell

Soup simmered merrily, its smell wafting appetisingly around Louis Pasteur’s laboratory in 19th century France. But Pasteur, the great chemist, was not cooking his lunch but conducting an experiment designed to dispel an illusion that had persisted for centuries.

Life, people had thought, sprang magically from rotting meat. They believed this because they had seen maggots crawling on bad meat and did not know that they had been hatched from flies’ eggs.

This is why Pasteur was boiling his soup in a long bottle with a neck so curved that dust could not enter it. The steam was so hot that it killed any bacteria in the neck of the bottle. And there were no bacteria in the soup because the heat had killed them.

After he had allowed the soup to cool and left it, Pasteur saw that no bacteria grew upon it. Then he broke the neck of the bottle so that dust in the air could settle upon it.

Bacteria then began to grow upon the cold soup because small bacterial spores had settled upon it.

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This edited article about soil originally appeared in Look and Learn issue number 687 published on 15 March 1975.

Farmer sowing seed by Peter Jackson

Without the thin, loose layer of soil or earth that covers most of the land surface of the world, there would be no plant life. Not only does the soil anchor and support plants so that they grow firm and upright, but the minerals, water and air trapped in it provide the plants’ food.

If there were no plant life, there would be no human or animal life. We and all the animals, birds, reptiles, insects and even fish live on plants directly or indirectly.

Soil, then, is one of the most important things in the world.

The earth in which plants are growing today was solid rock millions of years ago; and the solid rock of today will turn into soil millions of years hence.

The great soil makers are rain, ice and wind, helped by changes in temperature. These natural forces slowly break up the top surfaces of the rock and grind it into small pieces, or pebbles.

Thousands more years pass and the pebbles are ground down by the same forces, and also by rubbing against each other, into the small particles of earth we call soil. But it is constantly being changed by chemical action and the activity of bacteria and other microscopic organisms. True soil is formed only when living organisms start to become active.

Lichens, mosses and other kinds of simple and hardy plant life gain a foothold in the forming soil. These catch and retain fine particles of minerals carried by the wind and rain, and at the same time absorb or take up from the soil various minerals which serve them as food.

The decaying vegetation also releases certain acids and these dissolve many of the minerals present in the forming soil. The growing mosses and lichens release carbon dioxide which, with water in the soil, also helps to dissolve the minerals.

All this results in a thin layer of organic or living matter being built up on the surface of the forming soil.

Then larger and bushier mosses are able to take root. These trap and hold more minerals in greater quantities. When they die, their remains are added to the top layer which steadily becomes thicker and richer.

At last the soil is deep enough and rich enough to provide the firm support and mineral foods needed by grasses, shrubs and trees. The leaves and bits of bark and stalks shed by these plants fall on the soil and fertilize it, making it still richer. In this way a layer of humus begins to form.

The presence or absence of humus makes all the difference between a sterile soil and a rich and productive one. Humus holds in the soil nitrogen, minerals, gases and moisture essential to plant growth. It also keeps the soil warm so that the seeds of the higher forms of plant life can germinate.

This edited article about the dandelion originally appeared in Look and Learn issue number 686 published on 8 March 1975.

The Dandelion by Clive Uptton

“Dandelion” comes from the French “dent-delion,” meaning lion’s tooth. Look at the jagged edges of the flower’s leaves and you will see why.

Although the dandelion is spurned as a weed and ruthlessly destroyed, it is one of the most interesting of all wild flowers. Nature seems to have taken pity on the poor dandelion and given it the means to grow and flourish in spite of persecution. It even has parachutes with which to launch its seeds so that they have the best chances to root and grow.

If its flowers are cut close to the ground by a spade, scythe or mowing machine, a healing, cork-like substance called calus forms across the cut and protects the root. New shoots then spring up from the scar.

When growing on bare ground, the flower’s leaves lie flat and fit closely together but with very little overlapping. In this way the entire surface of the leaves gets the greatest possible amount of the air and sunshine essential to plant life. The leaves are so shaped, too, that when rain falls on them it runs down their centres and so reaches the root as soon as possible.

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