Does a black cat bring bad luck?

          Many people all over the world regard the sight of a black cat as inauspicious. If a cat crosses our path, we take it as a bad omen. Do you know why a cat in general and a black cat in particular are considered inauspicious?

          In fact, it is nothing but superstitious to consider a cat inauspicious. This superstition goes back to a belief of thousands of years. The ancient Egyptians worshipped the cat. They had a goddess called Pasht whose head resembled that of a cat. They believed that this goddess had nine lives. Whenever a black cat died in Egypt, its dead body was preserved as a mummy (preserved corpse of a human being or animal). Remains of thousands of black cats have been recovered from a cemetery of Egypt. Killing a cat was then considered as an offence, punishable with a death sentence. Thus people had a great fear of the sight of a black cat.



               During the middle ages witches and witch doctors always used the skull of a black cat to prepare mysterious medicines. As a result people started thinking that a black cat was a bad omen. Thus people have been suffering from this superstition for many centuries. The truth is that no cat is inauspicious. The cat is a pet animal that was domesticated about 5000 years ago. 


What are pain relievers?

          A pain reliever is a drug that reduces pain without causing unconsciousness or complete loss of feeling. In medical terminology, they are called analgesics. There are two main types of analgesics: The peripherally-acting analgesics or non-narcotic pain-relievers and the centrally acting analgesics or narcotic pain-relievers.

          The first type acts on any pain associated with muscles or bones or their related structures. Hence these are called peripherally-acting analgesics or ‘mild analgesics’. The most common of these is aspirin. Its active constituent is acetylsalicylic acid. It was first synthesized in 1899, and produced in huge commercial quantities ever since. Other analgesics of this group include analgin and paracetamol. These are used to relieve headaches, rheumatism and other body pains.



          The second groups of pain killers, the centrally-acting analgesics are very potent drugs and include substances derived from opium, an extract of the poppy plant. Two such analgesics are morphine and heroin. In the brain they depress the activity of the cortex, and thalamus which is the part that receives messages from the body’s pain receptors. They are very effective and act instantly when injected into a muscle or vein. They are only used by physicians for relieving intense pain of those suffering from cancer, heart attack or severe injuries involving broken bones or wounds. Some common drugs of this group are Codeine, Pentazocine and Ethoheptazine.



          Both types of analgesics have a number of side effects. For example, aspirin can irritate the stomach, cause indigestion or in serious cases it may even lead to an ulcer. If used indiscriminately, it may cause anaemia.



          Morphine drugs can cause nausea and vomiting, but this side-effect can be blocked by giving the drug Cyclizine along with it. Morphine and its allied drugs can cause addiction when used over a prolonged period.



          Some other analgesics such as antipyretics are used to bring down fever. In severe cases or while carrying out a surgical operation, doctors apply many anaesthetic drugs to deaden pain.



          These drugs are available under different brand names. Aspirin is available in the brand name of Disprin, Mejoral etc.; paracetamol is available in the name of Calpol, Crocin etc. Novalgin is an analgin whereas Fortwin is a brand of Pentazocine. It is always advisable to check the constituents before buying these drugs. 


Why do giraffes have a long neck?


               Giraffe is the tallest land animal in the world, but scientists are unable to explain how it got its long neck. A famous French zoologist, Jean Baptiste de Lamarck, proposed a theory that at one time giraffe’s neck was much shorter than what it is now. It had to raise its neck to eat the leaves of the trees. According to Lamarck, the part of the body which is used most develops most. The giraffe had to raise its neck time and again to reach the upper branches of trees when the leaves on lower branches were eaten away. This excessive use of the neck resulted in its gradual increase. The successive generations of the giraffe started having longer necks and finally today’s long-necked giraffe emerged.



               The male giraffes grow upto a height of 5.5 m and weigh more than 1, 000kg. It is an herbivore. It chews its food in spare time. The formation of giraffe’s body is such that its mouth can easily reach the leaves of high trees. Its tongue is about 45 cms long and so constructed that it can even eat the leaves of thorny plants. Its upper lip is long which helps it wrench off many leaves at a time.



               The colour of giraffes resembles the shadow of the trees and as such it is not easily visible to its enemies. It is usually yellowish-brown. Its ears are very sensitive.



               It can hear the faintest sounds, but it is nearly incapable of uttering sounds. The word ‘nearly’ has been used because some of the female giraffes and their young ones have been found mowing like cow or ox in the zoological parks but most of them do not utter sounds. The reason for this inability lies in the underdevelopment of its voice box or larynx. Probably due to this reason, it has a keen sense of smell and sight. If attacked, it can run at a speed of 45 kms per hour for an extended period of time without tiring. As far as fast running is concerned, it can beat even the fastest of horses. When it is attacked by some other animal, it retaliates with the help of its head and hind legs. As its eyes are far above the ground, it can easily see predators long before they can get close enough to attack. That is why even the lion has to be very cautious while attacking a giraffe. Lion always attacks it from behind because giraffe strikes with its head like a hammer.



 


What is a flying fish?


          There is a kind of fish which can glide like a glider. It is called a ‘flying fish’. It does not fly like birds, because it has no wings. It first swims very fast on the surface of water up to a speed of about 65 km/hr and then spreads its front fins and starts flying in the air. The fins remain spread firmly during the flight with the help of its muscles. But as soon as it lands on water, they shrink to their original position.



          The most common flying fish is the two-winged type, which is found in all tropical seas. It is about 25 cms long. The largest flying fish is about 45 cms long and has four wings. It lives off the coast of California. The length of flying fishes varies from 5 cms to 45 cms. Sometimes while flying it dashes against the water waves. At that time it looks very beautiful. The collision with waves gives it extra energy and it can further fly up to greater distances. It usually flies quite high in the air. A flying fish can glide for over half a minute. 


How fast can marine animals swim?

          The sea abounds with different kinds of living creatures such as fish, tortoise, crocodile, eel, dolphin, whale, etc. Do you know with what speed these animals can swim? 






          The sailfish swims the fastest amongst all the aquatic animals with a speed of up to 110 kms per hour. Next is the sword fish with a maximum speed of 95 kms per hour. The tunny and the rainbow trout can swim at a maximum speed of 75 kms per hour. The speed of dolphin goes up to 65 kms in an hour.



          Besides these, the swimming speed per hour of some other aquatic animals are: tarpon, 55 kms; shark, 45 kms; trout, 35 kms; salmon 25 kms, eel, whale and pike, 15 kms. Cray fish, carp, tench, perch, octopus, etc. swim at a speed of less than 10 kms per hour. These are not the normal speeds but are the maximum recorded speeds of sea animals.  



Which animals resemble man?

          Gorilla, chimpanzee and orangutan are some of the animals which resemble man many respects. They are a kind of monkeys without a tail. They fall under the ‘anthropoid’ category and are found in the dense jungles of Africa and Asia.

          Among these animals, chimpanzee has the closest resemblance to man. In fact, the bone structure of all these animals has many similarities to that of man. The number of their teeth and their constitution are similar to ours. Like human beings, they too have wrinkles on their forehead. Their skulls are also like ours. Even their blood is similar to ours. However they cannot speak like us. They eat blossoms, leaves, stems, fruits, insects and bird’s eggs. 





 



          Gorillas are generally as tall as human beings, but heavier and stronger. They live in groups of 20 to 30. The young ones live with their parents till they become adults. Young gorillas sleep on trees, while the adults, on the ground. They are generally peace-loving animals, but once teased or wounded, they start beating their breasts. They can produce a drumming sound from their mouth. Their skin is black.



 



 





          Chimpanzee is the cleverest of all these animals. It can imitate many habits of man. Its body is covered with black hair. It can be easily captured.



          Unlike gorilla and chimpanzee, the orangutan is almost completely arboreal. It has bony crests over the top of its skull. Its forehead is higher than that of gorilla and chimpanzee. The lips protrude and the ears are small. All these animals belong to the group to which we belong.



 


Do some plants eat insects?

               You will be surprised to know that there are some plants which catch and eat insects. Such plants are called insectivorous plants. Since they cannot prepare their own protein, they get it by eating insects and worms. Every plant of this kind uses it own technique for capturing insects. The leaves of these specialized plants are adapted to trap and digest insects - which supplement their food supply.



               One of the famous insectivorous plants is ‘pitcher plant’. The upper part of its leaf resembles a small pitcher. Its colour is very attractive. It contains a sticky liquid. The opening of the pitcher has small fibres which allow the insects to go inside but obstruct their coming out. On being attracted by the beautiful colour, when some insect enters this pitcher, it is unable to come out. It gets entangled in the juice of the pitcher and the plant produces certain enzymes and digests it. The ‘cobra plant’ of America which appears like a snake, also eats insects. It also has pitcher-shaped mouth.



               The ‘sundew plants’ have hair on their leaves. The tips of these hairs have droplets of a liquid which appear very attractive. As soon as some insect is attracted towards a leaf, these hairs bend forward, capture the insect and digest it with the help of their own juice. The digested flesh is absorbed through their leaves. After that the hairs again become normal.



               There is a plant called ‘venus-fly trap’ which is found in America. Its leaves have beautiful red coloured elevations on both sides. Whenever an insect sits on a leaf it closes like a fork and the plant digests the trapped insect by digestive juices. The ‘uticularia’ is a water plant. It is found all over the world. The roots of this plant which are submerged in water have bulbous bladders. When some aquatic insects enter the bladder, the hairs on its opening do not allow it to come out. The walls of these bladders give out digestive juices which suck the proteins out of the bodies of these small insects.



Similarly, a plant called ‘Indian pipe’ is found in the hills of Shimla. It also eats insects. In addition to these, there are many other insectivorous plants all over the world.



 


What is a Dragon?

         Dragon is a legendary dreadful monster that never existed in reality. It is a mythical figure born out of people’s imagination long time ago. The belief in this creature apparently arose without the slightest knowledge on the part of the ancients about the gigantic, prehistoric dragon like reptiles.

         The word ‘Dragon’ comes from the Greek word ‘Drakon’ which was used for a large serpent. But dragon as a monster represents a huge, fire-breathing, bat-winged scaly lizard or snake with a barbed tail. In later period it mostly remained in the shape of a snake. In the Eastern world where snakes are large and deadly, a dragon symbolized evil. But in the West it was accepted both as a symbol of good and evil depending on circumstances. On the whole its evil reputation was stronger. The Christians and Jews perceived it as evil and dangerous. In Christian arts, dragon represented sin and sorrow.



          The form and appearance of dragon varied from place to place. The Babylonian dragon had four legs and the Biblical dragon was described as a many-headed creature, like the Greek Hydra. In wartimes it was used as an emblem representing valour. In the 20th century the dragon was officially incorporated in the armorial bearings of the Prince of Wales. The Chinese dragon, known as lungs, appears as the national symbol. The Japanese as well as Chinese dragons are usually wingless. Dragon images are also used in the north-eastern states of India as well as in Bhutan during different festivals.



         The Komodo dragons found in some Indonesian Islands are infact very large lizards. However, the dragons in the general sense still are mythical figures. 


What is Darwin’s theory of evolution?


          For a long time it was believed that each form of life on the earth appeared separately and that none had ever changed its form. Charles Darwin was the first scientist who disproved this belief and laid the foundation of the modern theory of evolution. According to this theory, evolution is the process by which all living things on earth today descended from common ancestors that lived millions of years ago. All plants and animals have evolved in an orderly way and continue to change even now. 





          Charles Darwin was born in 1809. He received his education in Edinburgh University. He was deeply interested in the study of biology. When he was only twenty two, he got an opportunity to go around the world on a voyage on the Beagle ship of England. The voyage lasted five years and during this period Darwin could see many new countries and study different creatures. It was on this voyage that Darwin formed many ideas on evolution and adaption. After his return to England, Darwin received a letter from the naturalist Alfred Russel Wallace, who had formed similar conclusion about evolution. A joint paper by Darwin and Wallace was read in 1858. Darwin then wrote an account of his voyage and published it in the form of a book. The title of the book was The Origin of Species by Natural Selection. Its first edition was published in 1859. Setting a record, it was sold out on the very first day it appeared in the market.



          The Origin of Species attempted to prove on the basis of Darwin’s study that the living creatures had acquired their present shape and form after generations of evolution; and all of them had a common ancestry. In addition to this, his theory on natural selection explains that in the struggle for life only the fittest creature survives. Each organism differs slightly from its predecessor and in the course of time they acquired their present form. The book caused uproar when it was first published. Today, Darwin’s theories are widely accepted. Darwin devoted his entire life to the study of complex problems of biological science. He avoided entering the controversies surrounding his work and left it to others to debate the supposed consequences of “Darwinism”. The great naturalist died in 1882.



 


How long can man survive without food?


          Like air and water, food is also essential for all living beings. From the smallest insects to the biggest animals - all need food for their survival. So much so that even plants and trees can not live for long without food. Each person requires a certain amount of food daily, according to size, weight, age and amount of activity. Most of us feel upset if we skip just one meal, and if we try to go without food for 12 hours we would really be uncomfortable.



           Energy required for doing work is obtained from food. Cells and tissues damaged in doing work are repaired and replaced by it. It is very much needed for the growth and development of the body. In short, food is very essential for the proper functioning of the body.



          Now the question arises: how long can we survive without food? There are some animals which can store food in their bodies and live on it for a long time. It has been observed that the smaller and the more active the animal is more rapidly it consumes its stored food. Warm blooded animals use up their stores of food in the body more quickly. A dog can survive without food for 20 days at the most. However, the bug is such a wonderful creature that it can survive without food for one full year.



          But man cannot store food in his stomach. If he misses one meal, his condition becomes bad. Food is required to maintain the flow of blood. All the constituents of blood are obtained from food. The moment, the blood lacks nutritional materials, a signal, via blood, goes to the hunger centre of the brain and we start feeling hungry.



        There are a few examples of persons who survived for a very long time without food. Angus Warviern of Scotland survived without taking any food for 382 days i.e. from June 1965 to July 1966. During this period, he took only coffee, tea, water and soda water. One South African woman survived for 102 days on water and soda water only. Stefan Taylor of New Zealand remained alive for 40 days in 1970 on a daily intake of one tumbler of water only. These are some uncommon examples. Such people are endowed with exceptional power. Common man can at the most survive without food for three week. 


Why don’t women have beard?

            All mammals have some hair on their bodies and man is also a mammal. In some mammals hairs cover the whole body but in humans, hairs grow only in certain parts.



            Hairs on our body preserve the body warmth and protect the skin and body openings. They also help us in realizing the sensation of physical touch. The hair on our eyebrows and eye lashes, ear and nose help guard these body cavities against dust and insects.



            Now the question is, why do men have beards, and women do not? This can be understood as follows. When a child is born, he has only fur like hair on the body.



           As he grows, hair becomes harder. Boys and girls reach puberty at the age of 11 to 13 years. There is faster growth of sex glands at this age. In man, the testes and other sex glands, produce a group of hormones known as ‘androgens’. In woman, the ovaries and other sex glands, produce another group known as ‘estrogens’. The function of the androgens is to regulate secondary male sex features such as the growth of facial and chest hair and deepening of the male voice at puberty. The function of the estrogens is to regulate secondary female features, such as the change in the size of breasts, growth of pubic hair and onset of the menstrual cycle. There are various other changes in men and women brought about by these hormones. For example female body becomes soft and tender whereas, male body turns hard and strong. A special group of hormones called the ‘progestrogens’; are responsible for the regulation of pregnancy. Hence women do not have beards due to the absence of androgens.



 


How does our tongue tell us the taste?


            Man has five senses of perception – skin, ears, eyes, nose and tongue. The tongue tells us the taste of food and drink warns us if food has gone stale or is bad.



            The tongue is located inside the mouth and is an important muscle in our body. It is red in colour. If you examine it minutely, you will see granular bumps or projections on its upper surface, sides and back. These are called papillae. These papillae contain groups of contact called taste buds (chemoreceptors). They are composed of cells. Hairs like fibres emerge at the upper side of our tongue. At the lower end of the tongue, they end in nerve fibres of cells. These join the nerves of taste that lead to the brain.  



    The 4 main tastes are – sweet, salty, sour and bitter. All other tastes are a combination of two or more of these. These 4 main tastes are felt by different portions of our tongue. For example, salty and sweet tastes are felt by the tip of our tongue. Similarly, a sour taste is detected by the buds on the sides of the tongue and bitter taste, by the back portion of the tongue. The tongue is also sensitive to irritants such as pepper.


            The taste of food is known only when it is in the liquid state. As we chew our food, a portion of it dissolves in the saliva. This dissolved form of the food activates the particular taste buds. These generate nerve impulses and the nerve fibres carry these messages to the “taste centre” in the brain. The brain then perceives the taste.



            In addition to the tongue, our nose, which smells the food, also helps in perceiving the total taste of food. Smell is also a part of the taste. In the case of wine, cocoa and fruit juices, it is the smell which helps in the realization of the real taste. When liquids are taken into the mouth, the tongue experiences the taste while their smell enters the nose and through the “smell nerves”, it reaches the brain. In this way is derived the total pleasure of taste.



            When we suffer from cold, fever, or even constipation/indigestion, the taste buds get covered by some impurities and do not get properly activated. Heat of the body (in fever) or even hotness of food, also deactivates the taste buds. Hence, we do not perceive the real taste under such unhealthy conditions.



            The number of taste buds on the tongue of an adult is about 3000 which is much more than that of a child. As we grow older, the taste buds start losing vitality and, finally, become inactive, thus decreasing in number. In a 70-year-old man, for example, the number of taste buds is only 40. The taste buds, like all skin cells, are constantly being replaced. About half of the taste buds are replaced every ten days.



            



 


What happens to our body in sleep?


            Sleep is a bodily need that takes up about one third of life-span. After a whole day’s toil, both brain and body get tired. Sleep is necessary to restore energy and freshness to the tired organs and tissues of our body. It enables the body to repair worn out tissues and cells.



            Do you know how sleep comes to us and what happens to our body during sleep? According to scientific facts, there is a very complex area in the brain called “sleep centre”. Calcium ions present in the blood, control this centre. When an optimum quantity of calcium is received by the “sleep centre”, we get sleep. It has been observed from experiments on animals that they start sleeping when calcium is injected directly into the sleep centre. But if calcium is injected into the blood stream, this does not happen. During sleep, the sleep centre does two things. Firstly, it blocks off the brain so that we have no will-power or consciousness left and secondly, it blocks all nerves leading from the brain so that our internal organs and limbs fall asleep.



            In sleep, our body continues doing many types of movements. A man on an average changes his sides 20 to 40 times during sleep in one night. Blood circulation continues during sleep. Heart beat slows down a little bit. The digestive system works normally. Liver and kidneys perform their functions. The effects of sound, light, heat, smell etc. in sleep are the same on every sleeping person. During sleep, the body temperature is lowered by about one degree centigrade and the body cells are quietly engaged in getting rid of waste materials that have accumulated during the active part of the day.



How many hours a healthy person should sleep? The number of sleeping hours needed varies with individuals. The average adult needs from 7 to 9 hours of sleep. Boys and girls of 15 years of age need about 10 hours sleep each night. It is wise to form the habit of going to bed at the same time each night. Insomnia is the condition in which a person has difficulty in falling asleep. Such sleeplessness is often associated with pain, but worry can also keep a person awake. A dark, quite room that is well ventilated and cool is good for sound sleep. 


What causes people to faint?

               We often see that people faint on hearing some sad news or on getting frightened suddenly. The bodies get drenched in sweat and become cold. Their faces turn pale. Physical consciousness diminishes. Unconsciousness can be caused not only by a shocking news or terrible fear, but by many other factors also. People may faint because of confinement in a close and poorly ventilated room, or because of hunger, fatigue, severe pain, emotional shock certain heart condition of sudden fall in blood sugar. Now the question arises: why do people become unconscious?



               In order to know the reasons of fainting, it is essential to know what consciousness is. For the normal functioning of the brain, it is essential that there should be proper circulation of blood in the brain. As long as the brain is in receipt of proper supply of blood, all our physical activities remain normal. The normal functioning of the brain is in fact consciousness. If there is some obstruction in the supply of blood to the brain, the common physical processes get disturbed. Whatever may be the cause of fainting, man will become unconscious when normal supply of blood to the brain is disrupted. Hence, fainting or syncope is a temporary loss of unconsciousness resulting due to the insufficient supply of blood to the brain.



               The state of unconsciousness can be prevented by some measures. If somebody feels that he is about to faint, he should immediately lie down. If that is not possible, he should bend downwards and enclose his head in between the knees. Both these measures enhance the blood supply to the brain and as soon as the brain starts receiving proper quantity of blood, the chances of one’s becoming unconscious reduce.



               If somebody has become unconscious, he should be laid down and his clothes should be loosened so that he can breathe easily. His head should be kept at a little lower level than rest of his body. This will increase the blood supply to his brain and he will regain consciousness. Once he is conscious, he should be given tea or coffee. If somebody has fainted because of head injury or heat stroke, he should be taken to the hospital immediately. 





 

Why are people dwarf?


           Generally most of the people are of normal height, but sometimes we come across people who are exceptionally tall or small. Persons who are exceptionally small are called dwarfs. In circus you must have seen such dwarfs who entertain you.



          Do you know why some people lack normal height? The growth of a person depends on many factors. Heredity plays an important role in determining the height of a man or a woman. Children of tall parents are generally tall while of dwarf parents are dwarf. In Africa, some tribes such as the Watusi and the Masai have many men who are about 200 cm tall. At the same time, there are Pygmy tribes in Africa, whose people are only about 130 cm tall. These variations are due to heredity only.



            Disease is also a reason causing dwarfness. There are cases of dwarfness in which head and trunk are normal in size, but arms and legs are short. This is caused by disease of cartilage. A normal body skeleton increases in length during childhood and adolescence because cartilage changes into bone at the growing ends of the bones. Disease of the cartilage prevents arms and legs from growing to a normal size.



            Dwarfness is often caused by the lack of hormones produced by pituitary gland. The underactive pituitary gland during childhood does not allow the body to grow normally. This type of dwarfness can be treated by injecting hormones. Too much or too little growth is also determined by some disorder in adrenal, pituitary, thyroid and male and female sex glands (testes and ovaries). The growth retardation may also be due to inadequate nutrition and intake of vitamins. The restoration of an inadequate diet, vitamins and mineral intake will also cause the child’s growth to spurt. A dwarf, named Jeffery Hudson, eighteen inches tall served as a captain of cavalry in the British Army. He lived from 1619 to 1692.