Part 19

Where the bees do this it is because the bee has been visiting the flowers in his search for honey. They do not fly from flower to flower for the purpose of uniting the mother and father natures of plants, but they help the flowers incidentally while getting the honey for which they are searching. In gathering his honey the busy bee will go all over the father flower and get his legs all covered with pollen powder. Sooner or later he comes to a mother flower of the same kind of plant or tree from which he has father pollen on his legs, and, still bent on gathering honey, he incidentally rubs the pollen powder on to the ovary of the mother flower and the fertilization takes place. The wonderful thing about this is that the father pollen of one kind of a plant will not fertilize the mother nature of another kind of plant. To illustrate this, if a bee carrying pollen on his legs from a walnut blossom visits the mother blossom of a hickory tree the pollen of the walnut would not affect the hickory blossom, but would still have the proper effect on the first walnut mother blossom he visited.

This is how life in general is reproduced among the plants and trees. Life in the vegetable kingdom has no sense of feeling or any of the other senses, but this kind of life is still true to its own nature and is a wise thing in the plan of creation, because, since all seed will produce only plants like those from which the seed came, man can control the growth of the vegetables and fruits he needs as food. He knows when he plants corn that he will get corn in return, because perfect seed never makes a mistake. It would mix things up terribly for man if this were not so, because man might then plant one thing and find another thing growing. It would be a sad thing to plant wheat and find thistles growing.

In order that seeds may grow they must be planted under conditions that suit the kind of vegetable life in the seed. Man has to study and learn what these conditions are.

If a seed is planted too deeply the sun may not have a chance to warm the ground to that depth, and if it is planted too near the surface it may become too warm and be killed by the sun. When planted under the proper conditions the seed soon begins to grow. It grows upward toward the sun to get light and air, and it sends roots down into the ground to get food and moisture.

The life in the vegetable kingdom is soon able to take care of itself.

How Are Fishes Born?

The next step in the study of the reproduction of life brings us to the animal kingdom. The first thing we discover in this section is that in the animal kingdom father and mother natures are almost always separated. In plants and trees these parent natures are sometimes in the same flower, often separated, but on the same plant, and in other instances on different plants miles apart. What we must remember, then, is that in the case of plants it is given more or less to the chance of wind or other circumstances to bring the parent natures together.

In the animal kingdom there are a few cases where the mother and father natures are found in the same living object, as in the oyster and clam families, one of the lowest forms of animal life. These have but one of the five senses--that of feeling. This class of animals--the cold-blooded animals--includes the fishes, and in most members of this class the father and mother natures are separated and in different bodies. Step by step from now on we enter higher forms of animal life, and through each step we find a greater difference between the father and mother natures, and in the animal kingdom we speak of the father and mother natures as “_male_ and _female_.” In the animal kingdom, too, what we have previously called the seed is known as the _egg_. Seeds and eggs are the same so far as their usefulness is concerned, but we say eggs in the animal kingdom to distinguish from seeds in the vegetable kingdom.

Fish have eggs, then, and it is from the eggs that little fish are born into the world and grow to be of eatable size. You recognize the eggs of the fish in the “roe,” which is eaten as food. Not all fish eggs are used as food, however.

In the fish world the eggs are developed in the body of the female fish. Each little round speck in a “shad roe” is one egg, and there are many thousands in a single “roe.” Each egg will produce a little fish, under favorable conditions. These eggs develop in the body of the female fish in winter. In the spring, which is the time in which most living things are born, and, therefore, the time for hatching out fish eggs, all of the fish swim from the deep water where they live in winter to the places where the water is shallow and warm, and in these shallow waters the female fish expels the eggs from her body where the sun can get at them and hatch them by warming them. After the female fish has thus laid the eggs, the male fish swims over the eggs as they lay in the water, and expels from his body over them a fluid which is white in appearance and which fertilizes the fish eggs. If any of this fluid fails to reach some of the eggs it is not possible for the sun to bring them to life.

When the eggs are laid and fertilized the mother and father fishes swim away and they never see their children or recognize them as such, even if they meet them later in life. The parent fish do not act like other fathers and mothers, and they do not need to, because as soon as a baby fish is born he is able to find his own food and needs no help from father or mother to teach him how to find it or enable him to grow into a real fish.

Of course, many of the tiny fish are eaten by other fish and not all the eggs which the mother fishes lay hatch into live fish, because, if they did, the waters would be so crowded with fish that there would not be any room for the water. A single female fish will lay millions of eggs in a year, and if each egg developed into a fish there would be far too many.

This order of animals, which includes turtles, frogs, etc., is the cold-blooded class of animal life. They have only part of the five senses. They all can feel and some of the fishes can see and hear, but a great many of them, particularly those kinds which live on the bottom of the ocean, cannot either see or hear, and some members of the fish family cannot even swim.

The thing to remember about fishes in connection with the reproduction of life is that the mother fish must select a place which is favorable to deposit the eggs, but after that her responsibility ceases. The father merely fertilizes the eggs, and then his responsibility ceases. The little fish look out for themselves as soon as they are born and never know what it is to have a father or mother to look after them.

When we study the next higher form of animal life we find that the young ones have to be looked after, and that this becomes more necessary as we ascend the scale of animal life until we reach man, the most intelligent of all animals and yet the most helpless of all at birth.

How Birds Are Taught to Fly.

The next step brings us to the birds. Before they can look after themselves the little birds must learn how to search for food and the kinds of food good for them. They have to learn the habits of their kind of life. The higher you go in the study of animal life the greater seem to be the dangers which surround the young animals and the longer it takes to teach them how to look after themselves and what to do for themselves.

The bird family includes not only the robins, larks, sparrows and pigeons, but also the ducks, geese, and chickens, etc. We are all more or less familiar with birds’ eggs, and if not we know what a hen’s egg looks like. The eggs of the bird family are laid in nests, which is the first sign of home building in the animal kingdom.

The birds are the first of the large class of warm-blooded animals. The egg here represents again the reproductive power. The eggs, too, form in the body of the female bird, but are laid in a nest which the parent birds build together. Now this is the first step away from the fish family. The fish looks for a suitable place to lay the eggs and then goes off and leaves them. The birds, however, have to make a nest in which to deposit the eggs. The fish, as you remember, depended upon the warm sun shining on the shallow water to hatch out the eggs, thus depending on an outside force to supply the necessary warmth. In the bird family the mother bird must cover the eggs with her own body and keep them warm until they hatch out. Then, too, the father and mother birds feed the young until they are strong enough to fly and find food for themselves, and so the mother and father birds look after their babies until they are old enough to look after themselves. When this time arrives the old birds cease to bother about the young ones altogether. The fishes never act like parents after the baby fishes are born, because the little fish are able to look after themselves right away. The parent birds are a good deal like fathers and mothers for a time, but only so long as it takes them to teach their little bird children to look out for themselves. Then they forget the children completely.

It requires but a few days and no parental care to hatch out a family of baby fishes and no attention at all after birth. It requires several weeks and much patience for the parent birds to hatch out their eggs, and it involves care and attention for several weeks to teach baby birds to take care of themselves.

This being a father or mother in the animal kingdom becomes a greater responsibility in every step as we get closer to man, and when we reach man we find him to be the most helpless offspring of all at birth, and that it takes more time, care and attention to bring up a human child to maturity than any other animal.

What Makes the Hollow Place at One End of a Boiled Egg?

This hollow place on the end of the boiled egg (sometimes it shows on the side) is the air which is put inside of the egg when it is formed so that the little chicken will have air to breathe from the time it comes to life within the egg until it becomes strong enough to break the shell and go out into the world. There is also food in the egg for him. When you boil the egg this pocket of air within the shell, which would have been used up by the chick if the egg had been set to hatch instead of being cooked for breakfast, begins to fight for its space and pushes the boiling egg back and forms the hollow place.

The purpose of the air in the egg is a good thing to remember when we come to study the higher forms of animal life from the standpoint of how they reproduce themselves.

The mammals are the next higher form of animals. The babies of this class of animals must be fed for several weeks or months before they are ready to come into the world.

A little chicken is ready to come out of the egg almost as soon as it comes to life, and, therefore, needs only a little air and food before it is strong enough to peck its way out, but the babies of mammals begin to live months before they are ready to come into the world, and they need a great deal of air and food during this time. This class includes the dogs, horses, cows, cats and all other animals in the Zoo and in the woods. The name mammals means the same as “mamma,” and indicates an animal which must be fed from the body of a female mammal even after it is born.

In this class the eggs are retained within the body of the female animal instead of being laid in a nest or some other place, as in animals of lower classes, after being fertilized by the male animal, so that the baby animal may secure its food and air from within the mother’s body after the life within the egg is begun.

The mother’s body supplies the necessary warmth to develop the life of the little animal in the egg, just as the birds supplied this with their bodies. In the bird class it only takes a few hours to give the little bird sufficient strength to peek his way out, but in the mammal class it is a long time before the baby animal is strong enough to come out into the world, and even after it is born the babies of mammals require a great deal of care and attention before they are able to look out for themselves. During this period the animal secures all of its food from the breast of the mother animal.

Another reason why the eggs of mammals are retained within the bodies of the females is the need for protecting the young animals from enemies. In the animal kingdom each kind of animal preys upon another kind. They attack and devour each other and are constantly in danger. If, then, mammals laid eggs in nests and sat upon them to hatch them out, the mother animals sitting on the nests would be continually in danger of attack from their enemies. They would either have to flee and subject the nest and its contents to the danger of destruction or else stay and fight, and perhaps be destroyed. But by carrying her egg within her body the mother mammal is able to move about from place to place and protect her baby.

Is Man an Animal?

Men, women and children belong to the “mammal” class of animals. The offspring of the human family is the most helpless of all animals at birth. The young of most kinds of mammals can stand on their legs shortly after being born, but the human baby requires months before it can stand up. A baby horse can also walk within a few hours, but human children do not begin to walk until they are more than a year old.

Why Cannot Babies Walk as Soon as Born?

The human baby has a great many more things to learn than a horse baby before it is safe for him to go about alone. It takes time for the brain to develop, and if a baby could walk before the brain had even

## partially developed it would only get into trouble.

This, then, is what we have learned about the reproduction of life and the reasons for its being different in different classes of life. First, we had the division of organic life into the vegetable and animal kingdoms. Life in the vegetable kingdom has none of the five senses, for plants cannot see, hear, feel, smell or taste. They cannot move from place to place, but remain where they grow until destroyed or removed. On the other hand, all animal life has at least one of the five senses--feeling. The oysters and clams belong to this class. Starting with this level of life in the animal kingdom we find that as we go on up through the different classes we find each class able to do things which make it superior to the class below it, until we reach the human mammal, who can do most of all. And, further, that since each class as we go up in the scale of life has greater ability to do things than the class beneath it, so in each case the task of the parents in preparing their offspring for their kind of life becomes greater, and the period during which the offspring is learning becomes longer and longer until we reach the human family, in which we find that parents have the greatest responsibility, and the children are the most helpless of all animals, but that in the final result man has a right, on account of his superior qualities, to be the ruler of the other creatures of the world.

What Are Ball Bearings?

Some years ago a gentleman in trying to find some way to reduce the friction, which is constantly developed to a certain extent, even when the axle is oiled, discovered that if between the axle and the inside of the hub a circle of steel balls were arranged, so that the hub of the wheel did not touch the axle at all, but rested on the little balls which in their turn touched the axle, that a great deal of the friction was eliminated. This proved to be a wonderful invention, and when this combination is arranged and oiled, there is hardly any friction.

Why a Gasoline Engine Goes

[Illustration: FIG. 1.]

As you know, gasoline is a very inflammable fluid, and will explode if placed too close to fire.

This explosive quality is the basic principle of the gasoline engine. By admitting a small quantity of gasoline vapor into an enclosed cylinder, and exploding it by means of an electric spark, repeating this operation continuously, the engine is given a regular rotary motion.

Look at Fig. 1. Starting from the gasoline tank, the fluid is fed into the ‘carburetor’, which is a sort of atomizer. Here the gasoline is mixed with air, and broken up into a very fine spray, in which condition it will explode readily.

The engine will not start of itself. Its fly-wheel must first be turned by hand, or by some other outside force, until the first explosion takes place. After this its action is automatic.

As shown in Fig. 1, the fly-wheel is being turned, and is drawing the piston down the cylinder, which in turn sucks gasoline vapor, (shown by little arrows) through the ‘intake valve’. This ‘intake valve’, and the ‘exhaust valve’ on the opposite side of the cylinder, are opened and closed at the proper time through the action of the gears shown in the illustration.

Passing to Fig. 2, the fly-wheel in turning has drawn the piston to its lowest point, and is now shown forcing it up the cylinder. This compresses the gasoline vapor in the cylinder to a density at which its explosion produces the greatest amount of power. The intake and exhaust valves are both closed.

~WHAT CAUSES THE EXPLOSION IN A GAS ENGINE~

Fig. 3 shows the explosion. The cylinder has been filled with compressed gas, and the piston has again started on its downward travel. The spark plug, set in the top of the cylinder, makes a spark every time an electrical current passes through it. A switch on the engine permits the current to pass to the spark plug only when the engine is at this position in its action. (Fig. 3.) The consequent explosion drives the piston downward with great force, turning the fly-wheel, which by its weight continues the rotary motion after the downward impulse of the piston has been expended.

Fig. 4 shows the fly-wheel, still turning, forcing the piston up and thus expelling the burned gases from the cylinder through the exhaust valve, held open for this purpose. From this position the engine goes again to that of Fig. 1, and through 2, 3, and 4, continuously, exploding every second revolution, and giving a regular rotary motion to the fly-wheel.

[Illustration: FIG. 2.]

[Illustration: FIG. 3.]

[Illustration: FIG. 4.]

The illustrations show a one-cylinder motor, but these engines can be built with two or more cylinders, arranged to explode at different times, thus giving very smooth action to the fly-wheel and main shaft.

Aeroplanes, almost all automobiles, various pumps and other machinery are driven by gasoline engines. The rotary motion can readily be transmitted by chains or gears to the propellor of an aeroplane or motor boat, or the wheels of an automobile. It is only in the past few years that the gasoline engine has reached its present high state of perfection.

[Illustration: THE BEGINNING OF AN AUTOMOBILE

CRANKCASE SHOWING BEARINGS.

The heart of the automobile is the engine. It is built around the crankcase, which is its foundation or base.]

[Illustration: CRANKCASE WITH CRANKSHAFT AND FLY-WHEEL ADDED.

The crankshaft serves the same purpose in an automobile as the pedals do on a bicycle.

The fly-wheel on the end helps it to keep turning at an even speed.]

[Illustration: Gasoline vapor is exploded in the cylinders. This pushes the piston down, and as the piston is connected to the crankshaft it starts the crankshaft turning.

The piston and the rod that connect it to the crankshaft are just like the feet and limbs of any one riding a bicycle.

Cylinders showing piston in place and connected to crankshaft.]

[Illustration: The gears or “cog-wheels” are for running the fan, the pump and other parts.]

[Illustration: THE HEART OF THE AUTOMOBILE

Cylinder added to crankcase.

The cylinders are next bolted down to the crankcase, the pistons and crankshaft having been connected, as shown in Fig. 3. A cover is placed over the gears to keep them clean.]

[Illustration: An oil pan or reservoir is attached to the bottom of the crankcase to hold oil for the engine.]

[Illustration: The carburetor furnishes the gasoline vapor for the cylinders. It is connected to the engine by a crooked pipe called the intake manifold.

After the gasoline has been exploded a valve opens and allows the burned gases to escape through another pipe, called the exhaust manifold.]

[Illustration: Oil is poured in the spout which is at the left of the carburetor. It runs down into the reservoir and is pumped up through the engine a little at a time.

Oil pump and filler added to motor.]

[Illustration: THE POWER PLANT OF AN AUTOMOBILE

The electric generator makes electricity to be used for starting the engine and lighting the car.]

[Illustration: The magneto gives an electric spark, which explodes the gasoline in the cylinders.

The water pump keeps water flowing around the cylinders to prevent them from getting too hot. This water comes back to the pump through the radiator at the front of the car. Wind blows through the radiator and cools off the water. The tire pump on up-to-date cars is run by the engine. It does not pump except when the gears, which are shown in the picture, are pulled together.]

[Illustration: An electric motor starts the engine by turning the fly-wheel. This makes it unnecessary to get out and crank the car by hand.]

[Illustration: SECOND STAGE OF CONSTRUCTION

The transmission is added.