Nest of Tree Wasp.
Nest of Tree Wasp.
In the morning the wasps were all dead, and the boys examined the huge nest. Thus they were able to see queens, workers, and male wasps, eggs, larvæ, and pupæ, and to make drawings of each.
“What becomes of the wasps in winter?” Frank asked his uncle.
“They come to a sad end, Frank,” said Uncle George. “They do not store food like the hive bee, and so, when the cold weather comes, they starve to death.
Queen Humble Bee.Worker Humble Bee.
“Our good-humoured and hard-working friend, the humble bee, shares the same fate. A few young queens leave the nest before winter comes on. These bury themselves in mossy banks and sleep the winter through.”
Uncle George and the boys were having a stroll along a lane where briar and hawthorn and all sorts of wild flowers grew. Although it was an October day the sun was shining brightly, and all along the wayside the golden flowers of the dandelion opened wide to the sunlight.
“I thought that the dandelion was an early summer flower,” said Frank.
“So it is,” said his uncle; “but this year the autumn has been so warm that our dandelions are flowering a second time. This often happens with many of our wild flowers during an extra mild season.
“You ought to dig up one of these dandelion plants, take it home and grow it in a pot. It is a most interesting plant to observe, especially the growth and ripening of its seeds. I see here dandelion flowers in almost every stage of their growth.
“If you look you will find among the wide open flower-heads many others which are closed. Let us split a few of these down the centre, and we will find that they are not all alike.
“Here is one with a bright yellow tip. This one has not yet opened. If you use your lens you will notice that, like the daisy, this is not a single flower, but is made up of a great many small yellow florets. These florets stand upon a flat round disc, and they are surrounded by two rings of green things called bracts. One set of thesebracts stands up straight. These protect the florets. They open and close the flower. The down pointing bracts protect the flower from ants and crawling insects.
Dandelion.
Dandelion.
“Now, Frank, look at the split flower and tell me what you see with your glass.”
“The florets are all of one kind,” said Frank. “They are all strap shaped, and there are a great many of them. The younger florets are in the middle.”
“If you were to pull the florets out and count them you would find about three hundred of them in a single flower-head,” said Uncle George.
1. Dandelion Flower-head not yet opened.2. Single Floret of same.3, 4, 5. Flower-head closed for Seed ripening.6. Second time of opening.
“Now, take one single floret and examine it, please. It is very like the outer (white) florets of the daisy. But it is more complete. There is a large seed-vessel at the bottom. Just above this there are a great number of long silky hairs. You will see what these are for by and by. The lower part of the floret is tubular, but it opens up into a long yellow strap-shaped petal. There are really five petals all joined together here.”
“Oh yes,” said Frank, “at the top of the floret I can see five distinct teeth, and five ridges run down from them. I also see the barrel-shaped ring of stamens.”
“Let us gather some more of the closed flowers,” said Uncle George.
“Here are two other closed flowers. One of them has a yellow tip, withered and faded almost to brown. The other has a white woolly tip.”
“Have these not opened yet?” Tom asked.
“Oh yes! they have opened and closed up again. The dandelion opens out to the sun so that flying insects may visit it and carry pollen from flower to flower. When it has received, in this way, enough pollen to enable its seeds to form, it closes up completely and remains closed until its seeds are ripened. During this time the short stalk between the seed-vessel and petal part grows long. If you look again at a single floret you will see that this short stout stack bears the long straight hairs I spoke of. The flower-head closes so tightly that the yellow strap-shaped petal parts of the florets are squeezed together into a bunch. They soon wither. Meantime all the hair-tipped seed-stalks are growing longer and longer. At last they push the bunch of withered petals right out of the flower and it falls off.”
Uncle George then gathered a few more closed heads, and, by cutting them open, showed the boys all the stages in the growth of the seeds.
“When the dandelion flower-head opens for the last time, instead of a flat golden mass of florets, this is what appears.” As he spoke, Uncle George pointed to a dandelion head which was one huge fluffy ball of stalked seeds.
Frank held it up and blew his breath upon it. Immediately all the seeds went sailing through the air.
“Why does the flower-head keep closed when the seeds are ripening?” asked Tom.
“Because,” answered Uncle George, “not only has the seed to ripen, but a plumed stalk has to be formed by means of which the seed is carried away from the parent plant. These plumes have to be perfectly dry or they would be of no use as sails to the seed. Notice that it is only on dry days that these ‘clocks’ of the dandelion appear.”
“But, Uncle George,” said Frank, “are these seeds actually fitted with feathery tops so that they may be carried far away from the parent plant?”
“Certainly, my boy. You would not have them all trying to grow in the place where the parent plant grows, would you? There would be no room for three hundred seeds to grow there. Besides that, the parent plant has already exhausted the soil. It is necessary that they should seek pastures new, and therefore the seeds of most plants are furnished with some means of travelling.”
“Are all seeds carried by the wind?” Tom asked.
“Oh dear no,” Uncle George replied, “plants have many ways of scattering their seeds. Some plants, by suddenly bursting their seed-vessels, shoot their seeds far out; some seeds are furnished with little hooks which grip on to the fur of passing animals; some are carried by birds; but by far the greater number are scattered by the wind.
“We shall learn more about these at some future time. Meantime we will grow a dandelion plant athome, and watch the opening and closing of its flowers, and the wonderful way in which its travelling seeds are produced.”
TROUT
TROUT
One day in November the postman brought Uncle George a small wooden box. There were holes bored in the sides and top of it. The box, when opened, seemed to be filled with damp moss; but when some of this moss was removed there was found in the middle of the box a piece of folded muslin.
Hatching Bottle.A. Supply pipe.B. Exhaust pipe.C. Trout Eggs.Rearing Box.C. Perforated zinc tray to fit box.
Uncle George laid the muslin on the table, and opened it out. It contained a number of tiny pink balls, much smaller than peas.
“These are the trout eggs you promised to get for us, are they not?” said Frank.
“They are,” said Uncle George, “and we must putthem into running water at once. I have a bottle here ready for them.”
Uncle George filled a wide-mouthed bottle with water from the tap and placed the eggs in it. He then corked it with a cork in which he had bored two holes.
Into each of the holes he had fitted a tube. One tube was long enough to reach almost to the bottom of the bottle. The other was bent over the outside of the bottle.
The straight tube was connected with the water tap by a piece of indiarubber tubing. He then turned the tap on gently, so that the water went in by the straight tube and came dripping out by the bent tube.
“Trout require a constant supply of fresh water,” he said. “Their eggs are usually laid in shallow streams.
“Now, boys, I want you to watch these eggs and note down any changes you see in them. You can remove the bottle from the tap at any time, but you must not keep it more than fifteen minutes at a time, or your trout will not hatch.”
At the end of a week the boys noticed two black dots and a coiled white line in each egg.
In two weeks more some curious-looking creatures were seen wriggling about among the eggs. As there were some empty egg-skins to be seen, they guessed that these lively creatures must be young trout.
They were not a bit like fish. Each seemed to be made up of a long white streak, which looked like the “backbone” of a fish, a big, clumsy yellow bag with red veins running through it, and two large black spots that looked like eyes.
In a few days all the eggs hatched out, and in place of the little pink eggs there was a crowd of these wriggling creatures and a number of empty egg-skins. The boys were puzzled, and Uncle George had to be consulted.
Six Stages in Development of Trout.
Six Stages in Development of Trout.
“I don’t think these were trout eggs,” said Frank. “The creatures that came out of them are not a bit like fishes. They swim on their sides and have a huge yellow bag attached to their bodies.”
“Theyareyoung trout, I can assure you, Frank,” said his uncle laughing. “If you remember, your tadpoles were not a bit like frogs when they hatched out of the egg. These huge bags you talk of are called ‘yolks.’ Each trout when hatched is furnished with a huge yolk or food supply.
“The tadpole, when hatched, has also got a yolk upon which he lives without eating for four or five days. Our trout will require no food for six weeks. During that time the yolk will become smaller and smaller, and at last disappear entirely. While the yolk is shrinking, you will notice that the creature gradually assumes the form of a fish.”
Uncle George emptied the bottle containing the young trout into a wooden box which he had made. This box was fifteen inches long, four inches broad, and four inches deep. The inside of it he had charred with a red-hot iron after it was put together. It was placed under the tap, and the water dripped into it all day and all night.
Frank made a small gauze net about the size of a dessert-spoon, and with this they lifted troutlets out of the box whenever they wanted to examine them.
As their uncle had said, the creatures changed from day to day. By placing a single trout in a white saucer, the boys could note these changes; but they were such lively little creatures that making good sketches of them was somewhat difficult.
First the big black dots became more like eyes. Then delicate fins and tail appeared, and mouths which opened and shut. At the top of the yolk-sac, just under the head, the boys could see a little red thing like a heart beating constantly. As the yolk-sac grew smaller, the little fish’s body grew more shapely, and tiny brown spots appeared all over it.
At last, at the end of six weeks, the yolk was completely gone, and the young trout were now beautiful little fish, shaped and coloured exactly like big trout.
Then Uncle George began to feed them. They were fed four times a day on the yolk of an egg which had been boiled for half an hour. A very small quantity of this hard yolk was squeezed through a piece of gauze into the water, and the little fishes dashed at it and gobbled it up greedily.
They were so rapid in their movements, swimming about and leaping out of the water, that the boys were never tired of watching them.
“What are the brown spots on a trout for?” Frank asked his uncle one day.
“The trout is protected by his colour,” said Uncle George. “Each trout is coloured like the bed of the stream he lives in, and the spots resemble grains of sand and tiny pebbles. The trout can change his colour, like the frog, as I will show you.”
Uncle George took two trout out of the box and placed them in a glass dish. He placed the dish in a white saucer, and so arranged it that water was kept flowing into and out of it.
Next day he took two more trout out of the box and placed them in the glass dish. It was then seen that the first two trout had grown quite light in colour. They were much paler than those taken out of the box, the inside of which was charred and black.
One day Uncle George found two of the trout dead in the box.
“I am afraid, boys,” he said, “that we cannot keep them confined any longer. Get a large pail full of water, and we will carry them to the brook.”
“We must come here and fish next year, Frank,” said Tom, after the trout were transferred to the brook.“How long will it be before they become big trout, Uncle George?”
“They are now about an inch long,” said Uncle George. “In a year they will be four inches long. In about three years, if they are not devoured by larger trout, they will weigh about a pound apiece.”
“I think it is a shame to kill such pretty little creatures,” said Frank.
“I quite agree with you, Frank,” said his uncle.
The silkworm eggs came in a very small box. They were sent by a friend of Uncle George’s who lived in the south of England. The eggs were stuck to pieces of paper in scattered groups. Some pieces of paper had only one or two eggs on them, others had as many as forty. They were small, round things, flattened on the top, and coloured light green. They reminded the boys of small mustard seeds, but they were not so round.
In answer to Frank’s question as to why the eggs were laid in irregular groups, Uncle George answered:
“When the silk-moth emerges from her pupa case, she lays her eggs anywhere on the floor of her cage. As the eggs are coated with a gluey material when newly laid, they stick firmly to the floor.
“Those people who rear silkworms always have a sheet of clean paper covering the floor of the cage before egg-laying commences. After the eggs are laid, they are found adhering to this sheet of paper. The paper is taken out of the larva cage, and those parts containing eggs are cut out with scissors.”
“How many eggs are laid by one moth,” Frank asked.
“From four to five hundred,” his uncle replied. “Let us get our larva cage cleaned out, and we will put these eggs in the lower part of it and await their hatching.”
“Why in thelowerpart,” Frank asked, as he set about cleaning the cage.
“Because its floor is a drawer which can be pulled out. If you put them in the upper part, you must lay a sheet of paper on the floor first, for your silkworms must not be handled on any account.”
“And how long do we have to wait for these eggs to hatch?” asked Tom.
Larva Case.
Larva Case.
“That depends altogether upon the amount of warmth they receive, Tom. They will remain unhatched ever so long if kept in a cool place; but whenever they are placed where they can get the necessary amount of warmth, they begin to hatch. Let us put them in the front window, where they can get most sunshine.”
About a week after the larva cage was placed in the window, Frank reported to his uncle that some of the eggs had turned white.
“Take your lens and examine carefully those eggs which have lost their colour,” said Uncle George.
Lifting out one of the small pieces of paper with eggs on it, Frank examined it with the glass.
“Oh,” he said, “these colourless eggs are just empty shells, and there are two small creatures crawling along the edge of the paper. How small they are! They are no longer than the breadth of a pin-head. They are almost black in colour, covered all over with hair, and have very large heads.”
“Well, these are newly-hatched silkworms,” said Uncle George, “and they are already looking for food. Run out to the garden and bring in some fresh lettuce leaves.”
Uncle George carefully dried the lettuce leaves before putting them into the cage. In two days all the eggs were hatched, and in their place were as many black, hairy, crawling little creatures with clumsy heads. Although they did not seem to eat much, they grew very rapidly. When three days old, they were fully twice as big as when hatched.
In five days the silkworms seemed to have increased in number as well as in size. In fact, there seemed to be twice as many grubs as there were of eggs.
Then Uncle George explained that half of these were not grubs, but simply empty skins.
“The silkworm, in order to grow, must cast its skin,” he said. “It does this four times during its lifetime. Look out for anothermoult, or skin-casting, in four days’ time.”
Four days later the grubs cast their skins again, just as Uncle George had said. They were now about half an inch in length, and much lighter in colour.
In six further days they moulted a third time. Instead of dingy, hairy grubs, they were now hairless caterpillars,yellowish-white in colour, and with round black heads. Their fourth and last moult took place in another week. By this time they were over an inch in length. They now began to eat the lettuce leaves ravenously, and grew very fast. For ten days they ate much and grew rapidly. Then they seemed to get tired of feeding, and began to crawl lazily up the sides of their cage.
Silk Moth.1. Eggs.2. Larva.3. Silk Cocoon.4. Chrysalis.
Silk Moth.
“They are full grown now, boys,” said Uncle George, “and will soon begin to spin their silken cocoons.
“They are now about three inches long, and very different from the tiny hairy grubs which came out of the eggs over a month ago.”
“We have been comparing drawings of them with drawings we made of the caterpillar of the white cabbagebutterfly,” said Frank, “and we find that they are very much alike.”
“That is good,” said Uncle George. “They are, indeed, very much alike. The body is made up of thirteen segments, and they have the same number of legs. They differ from the cabbage caterpillar, however, in size and colour. Notice the little horn which sticks up out of the twelfth segment. Your cabbage caterpillar did not have that. If you look closely you will notice a long silk thread issuing from the head of one of these silk-spinning caterpillars. This one has just begun to make his cocoon; and, in order to prevent his threads becoming entangled with those of the other caterpillars, I will place this small paper cone over him.”
Next day Uncle George covered several of the caterpillars with paper cones. On the roof of the cage the boys saw one caterpillar surrounded with a flimsy web of silk of a golden-yellow colour. As they watched the creature turning its head round and round inside the silky veil, their uncle told them that the creature was spinning silk at the rate of about a foot per minute.
In three days each caterpillar had surrounded itself with a dense silken cocoon as large as a walnut. Then Uncle George took one of the cocoons, and, cutting it open, showed the boys the brown, shining chrysalis inside. He took another cocoon, and, having dipped it into warm water, began to wind the silken thread on to a piece of card.
Both Frank and Tom were amazed at the length of this silken thread. They were more surprised when theywere told that each caterpillar produces a silk thread more than half a mile long.
“Tell us, please, Uncle George,” said Frank, “why the creature spins all this silk, and how it makes it?”
“You are asking a difficult question,” said his uncle, “but I will tell you something about it.
S. Silk Fibres.W. Wool.C. Cotton.(All highly magnified.)
“The creature spins this cocoon to protect its chrysalis, of course. The silk is produced in two long, coiled tubes, which occupy nearly the whole length of the creature’s body.
“Silk, before it issues from the caterpillar’s body, is a fluid. Whenever it comes out into the air, it becomes horny. Two strands are produced at once—one from each of the long coiled tubes. Before they leave the caterpillar’s body they are pressed together to form one flat, ribbon-like thread. Silk is one of the strongest fibres in the world. It is nearly as strong as steel, and much stronger than many of our metals.
“In a fortnight your silken cocoons will produce white, fluffy moths. ‘Then you can supply your friends with hundreds of ‘silkworm’ eggs, and still have enough over to stock your larva cage.”
Silk Moths—Male and Female.
Silk Moths—Male and Female.
STRUCTURE OF STEMS.—One- and two-year-old twigs of horse-chestnut, elm, and willow should be cut into half-inch lengths and distributed among the class. If cut straight across with a sharp pen-knife, the different layers can be seen with the naked eye. Afterwards these pieces should be slit longitudinally, and the various tissuespeeled offby the pupils.
BULBS AND CORMS.—Bulbs of snowdrop and tulip, and corms of crocus, can be bought from seedsmen, from September to January, at from 6d. to 1s. per 100. At any other season of the year the onion will make a good substitute.
WILLOW TWIGSwill root readily if placed in water and kept near the hot pipes in school.
VEGETABLE FINGERS.—To illustrate this lesson, peas (of any kind) ought to be grown in school. Branches of the many wild peas and vetches are to be found in abundance in every hedgerow during spring, summer, and autumn. Branches of Virginia creeper, clematis, tropæolum (Indian cress) may be shown with advantage. The compound leaves of the rose, ash, or mountain ash should be shown along with those of sweet-pea and edible pea, and the amount of green (assimilating) area compared.
THE GREAT WATER BEETLEis found in nearly every pond. One or two should be kept and fed upon small worms. These beetles can also be obtained from any naturalist dealer. The larvæ of this beetle is found in ponds in summer months.
“WATER BOATMAN” BEETLES(notonectaandcorrixa) are common to all our ponds.
PLANT ARMOUR.—Branches of whin, bramble, hawthorn, and barberry, and leaves of holly, thistle, and nettle will be found to illustratethis lesson. Young whin plants are to be found plentifully in spring, growing under the old bushes. One of these should be grown in a pot in school and kept well watered. It will producenoprickles.
TROUT EGGSare obtainable from any of the fisheries—e.g., Howietoun Fisheries, Stirling, or Solway Fisheries, Dumfries, at about 1s. per 100, from October till April. They are easily hatched and reared wherever running water can be obtained. If not hatched in a bottle, as described in Lesson XIII., the ova ought to be placed in a shallow trough of perforated zinc suspended in a small wooden box. The inside of the box must be charred with a red-hot iron to prevent fungal growths. When the yolk-sac is completely absorbed, the young trout should be fed on yolk of hard-boiled egg, and, later on, on a mixture of this and chopped raw beef. In each case the food should be squeezed through perforated zinc.
“SILKWORMS.”—Eggs of the silk-bearing moth (Bombex Mori) can be had from Messrs Watkins & Doncaster, 36 Strand, London, and other dealers, at 4d. and 6d. per 100. The larva should be fed on mulberry or lettuce leaves, and the leaves should never be givenwet.
Caterpillars of Tiger Moth (Arctia caja), Emperor Moth (Saturnia carpini), or Puss Moth (Cerura vinula) should be kept for comparison.
[1]See Book III. Lesson 3.[2]Dyticus Marginalis.
[1]See Book III. Lesson 3.
[2]Dyticus Marginalis.
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The following List gives a rough idea of the main Contents in each Volume of this Series:—Vol. I.Jack Frost, Woods and Fields in Spring, Holly and Fir, The Rook, Chicks, Hedgehog, Beetle, Humble Bee.Vol. II.Sowing the Seed, Life of a Plant, A Country Walk, Harvest Time, Gulls, Squirrels, Air, Fire, Dew, Rain, etc.Vol. III.Birds—Seed Eaters and Insect Eaters, A Baby Plant, Uncle George’s Tank, Tadpoles, Frogs.Vol. IV.Snowdrop, Crocus, Tulip, Daisies, Water-beetle, Life of a Trout, Silkworms, Chaffinch, Song Thrush.Vol. V.Some British Forest Trees—Oak, Ash, Horse-chestnut, Elm, Birch, Willow, Beech, The Fir Tribe.Vol. VI.Bats, Field-mice, The Water-vole, Mole, Weasel, Reptiles, Newts, Stickle-backs, Crayfish, etc.Vol. VII.Butterflies and Moths, and how to collect them, Caterpillars, Beetles, Flies, etc.
The following List gives a rough idea of the main Contents in each Volume of this Series:—