Flowers Fruits And Seeds

Flower  that is, those that are beautiful or fragrant, or both  have always had a strong appeal for mankind. Poets of every age have praised them. Roses, tulips, gladioli, azaleas, chrysanthemums, phlox and a host of other plants are cultivate for their showy flowers. Experts are constantly seeking to improve upon nature by making blossoms larger, more showy and more fragrant. The arrangement of flowers is an esteemed art. In the scheme of nature, however, a flower is more than an object of beauty. It is a reproductive organ, by means of which a plant carries on its kind. The most beautiful and fragrant of the flowers are concerned with this task. So are inconspicuous flowers, such as those of the ragweed, and ill smelling flowers, such as we find in the skunk cabbage and the Dutchman's pipe. The only plants whose reproductive processes are centered in flowers are the angiosperms, or flowering plants, which are the most highly evolved of all. In the flowers of angiosperms, as in the reproductive organs of the higher animals, a new organ-ism arises when an egg is fertilized by a sperm. There is an important difference, however. In the higher animals the re-productive organs produce the sex cells eggs and sperm directly. The reproductive organs of flowering plants produce spores first; then egg and sperm cells develop from the spores. The visible plant of an angiosperm  an oak tree, or a rose bush or a lilac represents the spore producing stage. The sexual stage is rep-resented only by the short span between the formation of spores and the production of sex cells by the spores shortly after their formation. Each flower originates in a bud, just as leafy  shoots do.various sequestration methods science daily. In the leafy shoot, leaves arise in the bud as minute projections at the sides of a dome shaped or slightly flattened stem tip, or growing point. In many plants the same stem tip that forms leaves changes later into a floral structure. It produces the small lateral  projections that will develop into floral organs, in much the same way that it formed the young leaves. What determines whether a plant will put forth leaves or flowers? Various factors are involved. To yield flowers there must be ample stores of food in the plant, in the form of proteins and carbohydrates. Likewise certain hormones, called florins, must be produced. Florins arise in many plants after a certain age has been reached. In such cases the plant turns to flowering after it has produced a certain number of leaves. 

                          

Heat Engines

MAN'S puny strength would never suffice to accomplish all the tasks that his fertile brain suggests. To help him perform these tasks, he has provided himself with a variety of power sources  heat, wind, water flowing downhill, electricity and, within recent years, the splitting of atoms in nuclear reactors. Heat is among the most useful of these sources of power. It drives most land vehicles (passenger automobiles, trucks, locomotives, tractors), marine craft (ocean liners, freighters, warships, motorboats) and aircraft (propelled planes, turboprops, turbojets, rockets). It serves to generate electricity in power stations and on farms. It operates blowers, pumps, certain types of fans and many other devices. In all heat engines, the chemical reaction that takes place when fuel is burned imparts a high degree of kinetic energy (energy of motion) to countless gas molecules. Generally these particles strike certain movable parts, such as pistons or the vanes of turbines, and these movable parts provide driving force. In the case of certain airplanes a forward thrust is produced as expanding gas is expelled from a nozzle set at the rear of the plane. 

An ancient Greek mathematician and physicist, Hero of Alexandria (we do not know just when he flourished), was prob-ably the first to show that heat energy could be used to perform work. He invented a steam engine called the Paleolithic , which worked on much the same principle as a modern rotary lawn sprinkler.A high return on capital tilts the kids science magazines. This engine consisted of a globe mounted between two tubes projecting upward from a steam boiler. The bent upper ends of the tubes passed through holes in the globe, which could rotate freely. Two bent nozzles were attached at opposite sides of the globe. The water in the boiler was heated the steam passed from the boiler through the upright tubes into the globe and then out through the bent nozzles attached to the globe. The reactive force of the steam issuing from the nozzles caused the globe to spin rapidly. Hero never put his Paleolithic, which was a form of steam turbine, to any practical use. 

                                        

The Planet Earth

FOUR planets in the solar system are smaller than the planet earth ; four are considerably larger. The earth, therefore, is not an outstanding member of the vast solar family. However it is the most important of all the planets to you and me, for it is our home in space  the vantage point from which we view the universe. Many theories have been proposed to explain the origin of the earth and the other planets. We have discussed some of them in other articles . They are little more than ingenious conjectures, for they are based on insufficient data. However, though we know little about the beginnings of our planet, we know a great deal about its shape, structure, properties and motions. We are quite certain that the earth is round or nearly so. Photographs of the earth taken from rockets soaring far above its surface show distinctly the curvature of our planet. Before this factual evidence became available, we could infer the roundness of the earth from certain facts. It was known, for example, that the hull of a receding ship, following the curve of the earth, disappears from view before its superstructure does. It was known also that as a total lunar eclipse develops, the earth casts a curved shadow on the moon. The earth is not a perfect sphere. Technically speaking, it is an oblate spheroid, or flattened sphere. Our planet bulges somewhat at the equator, because of its rotation. It is believed that while the earth was still in a molten state, its spin caused particles to be forced outward from the . axis of rotation. The particles were piled up least of all near the poles and most of all at the equator. Later a solid crust formed at the surface of the sphere, which had become slightly distorted. 

The diameter of the earth is 7,900 miles from pole to pole, and it is 7,927 miles in the equatorial zone. The difference between the diameters is comparatively slight, therefore  it comes to a little more than one part in 300. If the earth were represented by a globe 18 inches in diameter, the polar radius would be only 1/32 of an inch less than the equatorial radius. Someone has said that the earth is more nearly a sphere than most of the balls you would find in a bowling alley. 

The Industrial Revolution

The American Revolution has had innumerable chroniclers ; the glory and the horrors of the French Revolution are just as familiar. But the story of the Industrial Revolution, whose impact on society has become more and more pronounced as the years go by, has less often been told. The Industrial Revolution evolved through a remarkable series of inventions, going back at least as far as the middle years of the eighteenth century. Power machinery was substituted for hand tools ; the factory system first supplemented and then replaced the domestic system of work ; and industry gradually assumed the form that is familiar to us. The basic drive behind the Industrial Revolution was production. By the use of laborsaving machinery it became possible to produce far greater quantities of goods  for example, cloth  than earlier generations had deemed possible. We of the twentieth century are so much the children of the Industrial Revolution that we sometimes forget how differently men lived be-fore they learned how to harness power and set the forces of nature to do the heavy work of the world. The men who invented the machines that made the Industrial Revolution were not so much scientists as artisans carpenters, weavers, millwrights and instrument-makers, with a few mathematicians and clergymen thrown in for good measure. But the men who were chiefly responsible for carrying forward the Industrial Revolution were businessmen, capitalists and entrepreneurs (risk takers). You can compare them with the merchant adventurers of earlier centuries, who had supported scientific exploration.  From the outset these new industrialists were aware of the need for science and research in the technological development of industry. Here, for example, is part of a letter written in 1780 by Matthew Bouillon, an English manufacturer : 
                                 

 

Science in Revolution

THE last third of the eighteenth century was the period of the political upheavals that we know as the American and French revolutions. In this era there also occurred an Industrial Revolution and a Chemical Revolution, which were likewise supremely important. The Industrial Revolution involved the substitution of machinery for hand tools, the introduction of the factory system and the rise of mass production. In the course of the Chemical Revolution, old, erroneous theories were rapidly over-thrown and the science of chemistry was placed on a firm foundation. It has been pointed out that revolutions are simply signals that evolution has taken place. The forces that produce them have been gathering momentum for a long time before they break out into visible and sometimes violent changes of existing conditions. The American Revolution, which began in 1775, resulted from the gradually increasing strength of the colonies and their growing unwillingness to play a subordinate role, as well as from such specific happenings as the passing of the Stamp Act (1765), the Boston Massacre (1770) and the Boston Tea Party (1773). The age-old misery of the French peasants, popular displeasure over the privileges enjoyed by the upper classes and the spirit of defiance engendered by the French "philosophers" of the eighteenth century all these factors had molded the spirit of the French people over a period of many years, so that the actual outbreak of revolution in 1789 came merely as a long anticipated climax. 

So it was with the Chemical and Industrial revolutions. The Chemical Revolution did not spring full fledged from the brow of some scientific Zeus. It was the product of many generations of scientists and pseudo scientists, who had gruelingly accumulated facts and advanced theories. The Industrial Revolution, in its beginnings, was not so intimately bound up with the history of a science, but it was rooted partly, at least, in earlier scientific achievement.the most complex science related articles facing humanity today It waxed and grew as men realized more and more that the methods of scientific thinking could be applied to the problems of industry and could bring about astonishing improvements in the manufacture and distribution of goods. One of the important results, indeed, of the Industrial Revolution was the development of applied science, or technology. 

Acorn Worm

The acorn worms look like elongated worms with an acorn like head. The "acorn" is made up of a proboscis, or tubular structure, and a collar, into which the proboscis fits. The collar is attached to a long, flat, ruffled trunk, tapering toward the end. The animal ranges in length from an inch to four feet ; the average length is from six to ten inches. These relatively rare creatures are found on the Atlantic coast, buried in the mud and sand of the low tide zones. Like in the same way as in the vertebrates and is made up of the same tissue. Other authorities deny that the acorn worm has a chordate. They include the animal with the invertebrates, because it resembles them in many respects. The acorn worm's pharynx leads into the intestine, which is perforated with gill slits. The gills lead into a pouch, which opens to the exterior by gill pores. The intestine runs the length of the body. It ends in an anus at the tapered end of the trunk. The reproductive organs are located at the front end of the trunk. The sexes are separate; males produce sperm and females eggs. Fertilization takes place outside of the body after the sperm and eggs have been ejected from it. Some deep sea types, such as Hydrocephalus, reproduce asexually by budding. The larvae of acorn worms resemble those of the echinoderms (sea stars, sea urchins and their kin) in both structure and development. For this reason many believe that the chordates are descended from the same stock as the echinoderms. 
             

 shallow sea water one often finds orange, red or purple bearlike objects attached to rocks, piles and seaweed. These colorful "bags" are the primitive chordates In the adult animal, water bearing food particles passes through the mouth and is  filtered through gill slits. Food particles are trapped by the gill slits and enter the intestine. The water then flows into a surrounding sac  the atrium  and out through the siphon called the atrial pore. Undigested waste materials also pass out of the body by way of the atrial pore. Communicates can reproduce by budding. An adult buds again and again, producing new individuals. In time a large colony may develop on a rocky surface. Sexual reproduction also occurs. Communicates are hermaphrodites: that is, each animal produces male and female sex cells sperm and eggs. Fertilization may take place within the body ; or eggs and sperm may pass out of the body and unite elsewhere. 

Resort Climates

For a long time, many Europeans have placed much faith in the curative and restorative powers of clean air, sunshine, and pleasant weather. A 1964 report of the World Meteorological Organization in Geneva used phrases such as "climatic treatment" and "specific climatic therapy." It has been alleged that blood circulation, respiration, and skin condition are made health by exposure to favorable weather. These notions have resulted in the establishment of many health resorts in mountainous and southern-coastal areas. Baths in warm, sulfur-laden waters of certain natural springs are often part of the treatment. The benefit of the redolent waters and the air that surrounds them is debatable, but a week or two in a climatically optimal resort may send a city dweller home with a healthier mind and body. European climatologists have given a great deal of study to the most appropriate attributes of resort areas. To a certain extent, these depend on the purpose of the resort and the conditions of the people it seeks to attract. Generally, anyone seeking a pleasant period of recuperation from an illness is advised to avoid the following conditions: intense heat, particularly if accompanied by high humidity; polluted air, especially if the patient has had some kind of respiratory illness; highly changeable weather with frequent passages of fronts and cyclones; and excessively high elevations, where the presence of oxygen in the atmosphere may be too low. Sanatorium should be far enough from cities and industries to assure low concentrations of gaseous and particulate pollutants Local vegetation should be of varieties that produce little pollen. The clean, brisk air often found at moderately high elevations on the lee of a ridge or along a sea coast dominated by light sea breezes is recommended for summer resorts. On mountains or hilly terrain, spas are sometimes located in forest glades, where they are protected from strong winds by tall trees. Sunshine is considered therapeutic in many parts of the world. The World Meteorological Organization report, cited earlier, discusses the value of solar ultraviolet radiation in "hydrotherapy." These rays arc "used for their effects on skin cell metabolism, formation of substances such as vitamin I and detoxification processes." Hydrotherapy calls for long periods of exposure to the sun. Today, in the United States and a number of other countries, it is recognized that the risk of skin cancer through excessive exposure to sunlight exceeds the benefits of such exposure. In the Western Hemisphere, there is relatively little stress on health resorts, but a great many people migrate to the sunny south lands in winter. 

Comfort and Health

It is easy not to appreciate the full impact of the atmosphere on human well biophysical and psychological. Violent weather is obviously traumatic, causing injury and death to thousands every year; the effects of polluted air, though not so dramatic can still be tragic, particularly for the very young and very old with already existing lung problems. Sometimes the weather has such subtle influences that the hows and whys remain a mystery. For example, certain asthmatics find miracles in the desert air of southern Arizona while others find only disappointment, and the reasons for the differences still have not been found. It is sometimes difficult to specify in detail how the weather affects human behavior and psychological well-being, but there is no doubt that it does. Who can forget the joys of the first warm, sunny days of spring after a seemingly endless cold, gloomy winter? Also, it is well established that the strong, dry, gusty winds of the alpine foe and the California Santa Ana are associated with increases in abnormal behavior. No one needs to be told which weather conditions are physically pleasant and which ones cause discomfort. The most important element is temperature, but strong winds make cold days scent colder and hot days hotter and have many other effects as well. Even at moderate temperatures, atmospheric humanities affect human perception of air temperature. When the relative humidity is low, most people react as if the temperature were below its true value; when humidity is high, the opposite occurs. Investigations have been made of the losses and gains of heat by the human body as functions of temperature, humidity, and wind speed. Such information is particularly important in the design of clothing for use by people living and working in extreme environments . For example, the maintenance crews along the Alaskan oil pipeline must be protected from the frigid conditions that can cause frostbite or hypothermia. •

Aviation

Anyone who flies an airplane, a glider, or a balloon should take the weather into account before leaving the ground. Commercial and military pilots have ready access to the necessary information. Airplanes are designed to withstand the normal stresses imposed by violet weather events of the kind discussed in this chapter. Unfortunately there still are those rare circumstances where inclement weather, combined with pilot errors, leads to fatal accidents. The more a flier knows, through study and experience, the smaller the likelihood of such an episode. The major meteorological factors that affect an airplane in flight are wind, turbulence, lightning, hail, and aircraft icing (that is, the accumulation of ice on the leading edges of an airplane flying through a super cooled cloud). But weather considerations must begin at the runway. The length of runway needed for takeoff depends on the type and weight of the airplane, the elevation of the airport, the wind velocity, the air temperature, and the humidity. The lift imparted to an airplane's wings at any speed depends on the as density that is, the mass of air in unit volume of space which decreases with height. Departing airplanes must move faster in Denver (elevation about 5,300 feet) than in Chicago (elevation about 670 feet) to take off. To reach the higher speed, airplanes in Denver need longer runways. In addition, as the air temperature and (to a lesser extent) the humidity rise, the air density decreases; so longer takeoff runs are needed in summer than in winter. The altitude of an aircraft is usually measured by a pressure altimeter, which is calibrated according to the average pressure height relationship of the atmosphere.  Although labeled in units of altitude, the instrument actually responds to air pressure, which is a (unction of height. Since vertical distributions of temperature and density vary with time and place, so do the pressure at the ground and the rate at which pressure decreases with height. To take the deviations from average into account, a pilot adjusts the altimeter before takeoff and landing. Knowing the atmospheric pressure at the airport, the pilot sets the altimeter so that it reads the field elevation  when the airplane is on the ground. Up-to-date "altimeter settings" are normally supplied, via radio, from airport control towers. When air temperatures at flight altitudes are lower than the averages used to calibrate the altimeter, the actual altitude of the airplane is less than the one given by the altimeter; air temperatures above the averages have the opposite effect. Knowing the temperature, a pilot can easily compute a corrected altitude. Two important concerns in air travel are ceiling, which is defined as the height of the base of the lowest layer of clouds or other obscuring phenomenon that hides more than half the sky, and visibility, the greatest distance at which one can see and identify prominent objects. Low ceilings and visibility most often result from fogs or stratus clouds, but heavy snow or rain, blowing sand, or dense smoke and haze can also be causes. These conditions arc most significant during landings and takeoffs. In very dense fogs, ceilings and visibility can be nearly zero, bringing traffic to a halt. Fortunately, these "zero zero" conditions are not common. More often, ceilings are reduced to a few hundred feet and visibility to less than a mile, in which cases air traffic continues, though at a slower rate, in and out of airports having suitable radio or radar systems that can guide an airplane to a safe touchdown. Some types of fogs and low cloud layers form or become more dense on clear nights as a result of cooling by thermal radiation to the night sky. For this reason, ceilings and visibility may drop during the night and early morning. Pilots of small airplanes, who are often required to fly with the ground in sight, should schedule flights out of fog-prone airports for periods after the sun has burned off the fog and before fog begins to form in the evening or night.