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fixed place for habitation. The cultivation of grains and cereals gave them a store of food which could be used at times when other food was scarce. The word cereal (derived from Ceres, the Roman Goddess of Agriculture) shows the importance of this crop to Roman civilization. From earliest times the growing of grain and the progress of civilization have gone hand in hand. As nations have advanced in power, their dependence upon the cereal crops has been greater and greater.
"Indian corn," says John Fiske, in The Discovery of America, "has played a most important part in the discovery of the New World. It could be
planted without clearing or plowing the soil. There was no need of threshing or winnowing. Sown in tilled land, it yields more than twice as much food per acre as any other kind of grain. This was of incalculable advantage to the English settlers in New England, who would have found it much harder to gain a secure foothold upon the soil if they had had to begin by preparing it for wheat or rye."
To-day, in spite of the great wealth which comes from our mineral resources, live stock, and manufactured products, the surest index of our country's prosperity is the size of the wheat and corn crop. According to the last census, the amount of capital invested in agriculture was over twenty billion dollars, while that invested in manufactures was less than one half that amount.
Two billion six hundred and sixty-six million four hundred forty thousand two hundred and seventy-nine bushels of corn were raised in the United States during the year 1900. This figure is so enormous that it has but little meaning to us. In the past half century our corn crop has increased over 350 per cent. Illinois and Iowa are the greatest corn-producing states, each having a yearly record of over four hundred million bushels. The figure on page 62 shows the principal corn-producing areas in the United States.
Cotton Crop in United States-Percentage Source
Percentage Consumption-United States Cotton Crop
Alabama S.Can. Ark. La. N.C.Other States
Great Britain & Ireland
France lt. Rst.Wld.
Indian corn is put to many uses. It is a valuable food. It contains a large proportion of starch, from which glucose and alcohol are made. Machine oil and soap are made from it. The leaves and stalk are an excellent fodder; they can be made into paper and packing material. Mattresses can be stuffed with the husks. The pith is used as a protective belt placed below the water line of our huge battle ships. Corn cobs are used for fuel, one hundred bushels having the fuel value of a ton of coal. Wheat is the crop of next greatest importance in size, and is
of even greater money value to this country. Nearly six hundred and sixty million of bushels were raised in this country in 1900, representing a total money value of $ 500,000,000. Seventy-two per cent of all the wheat raised comes from the North Central States and California. About three fourths of the wheat crop is exported, nearly one half of it to Great Britain. Wheat has its chief use in its manufacture into flour. This forms the chief industry of Minneapolis, Minnesota, and several other large and wealthy cities in this country. The germ, or young wheat plant, is sifted from the flour and made into breakfast foods.
OTHER FRUITS. Of the other grain and cereals raised in this country, oats are the most important crop. Hay as a fodder crop is of great value next to that of corn, nearly $500,000,000 worth being raised every year. Buckwheat, barley, and rye are also raised in considerable amounts, but are relatively unimportant commercially. Among our fruits cotton is probably that of the most importance to the outside world. Over ten million bales of five hundred pounds each are raised annually. Of this amount a large amount is exported, the United States producing over three fourths of the world's cotton supply. The relation of source and distribution of the cotton crop can be seen by a glance at the accompanying diagram.
Other important fruit crops might be mentioned. There are over one hundred and seventy-five million bushels of apples produced every year in the United States. Pears, peaches, plums, cherries, and grapes play an important part in the crop, especially in California, which produces yearly over seven hundred million pounds of grapes, over fifty per cent of the total yield in the United States.
FOR THE PUPIL
Dana, Plants and Their Children, pages 27-49. American Book Company.
Newell, Reader in Botany, pages 97-137. Ginn and Company.
FOR THE TEACHER
Bailey, The Evolution of our Native Fruits. The Macmillan Company.
Hodge, Nature Study and Life, Chaps. X, XI. Ginn and Company.
Sargent, Corn Plants. Houghton, Mifflin, and Company.
Kerner (translated by Oliver), Natural History of Plants. Henry Holt and Com
pany. 4 Vols. Vol. II, Part 2.
HUNTER'S BIOL.— -5
VI. SEEDS AND SEEDLINGS
Relation of Flower to Fruit. We have already found in our study of the fruit that the bean pod is a direct outgrowth from the flower. It is, in fact, the ovary of the flower, with the parts immediately surrounding it, which has grown larger to make a fruit.
Use of Fruit. —The fruit is the most important result of the flower. It holds and protects the seeds until the time comes that they are able to germinate and produce new plants like the original plant from which they grew.
Study of a Bean. - Let us now take up the careful study of a bean in order better to understand how the seed may produce a young plant. For this purpose we need some dry pods of the string bean and some kidney beans.1
If we have already studied the pod of the bean, it will now be easy for us to find and identify the parts of the pod which were style, stigma, and ovary in the flower. Opening the pod along one of the edges or sutures of the two valves, we find the seeds fastened to the placenta each by the little stalk or funiculus. If we pull a single bean from its attachment, we find the funiculus leaves a scar on the coat of the bean; this scar is called the hilum. Look near the hilum for a tiny hole called the micropyle. (Do not confuse it with a little knob called the strophiole.) Turn back to the figure showing the ovule in the ovary. Find there the little hole through which the pollen tube reached the embryo sac. This hole is called the micropyle, and is identical with the micropyle in the seed. Draw a single kidney bean from the edge bearing the hilum scar, and show exactly the location of the hilum, micropyle, and strophiole. Make the drawing twice natural size.
Home Experiment. Divide ten kidney beans of nearly equal size into two lots. Cover the micropyles of one lot with wax or vaseline, weigh both lots of seeds exactly, then leave them in water over night. Weigh both lots in the morning. Note any differences in the appearance of the two lots of seeds. What is one use of the micropyle to the bean seed? This experiment may be made more instructive by covering a third lot of beans completely with wax and exposing them to the same conditions as you did the others. Does any water get in through the seed coats? Remove carefully the coat from a kidney bean which has been soaked over night in water. This coat, because of its toughness, is called the testa. Do you find another coat under it? You find the bean separates into two parts; these are called the cotyledons. If you separate the cotyledons very carefully, you find certain other structures between them. The rodlike part is called the hypocotyl (meaning under the cotyledons). This will later form the root (and part of the stem) of the young plant. Look for the first
1 For extended laboratory study on the bean, see Hunter and Valentine, Manual, page 13.
true leaves folded together between the cotyledons. How many leaves are there? That part of the plant above the cotyledons is known as the plumule or epicotyl (meaning above the cotyledons). Later we shall wish to know what part of the future plant the epicotyl forms.
All the parts of the seed within the seed coats together form the embryo or young plant.
Draw the bean to show all the above parts, twice natural size. Label every part carefully.
Food in the Cotyledons. The problem now before us is to find out how the embryo of the bean is adapted to grow into an adult plant. Up to this stage of its existence it has had the advantage of food and protection from the parent plant. Now it must begin the battle of life alone. We shall find in all our work with plants and animals that the problem of food supply is always the most important problem to be solved by the growing organism. Let us see if the embryo is able to get a start in life (which many animals get in the egg) from food provided for it within its own body.
Experiment. Mash up a little piece of a bean cotyledon which you have previously soaked in water. Test for starch with iodine solution. What color appears? If you now mount a little of the stained material in water on a glass slide under the compound microscope, you will find that the starch is contained in the form of little ovoid bodies called starch grains. The starch grains and other food products are made use of by the growing plant in a manner which we shall later know more about.
Test the cotyledon of a bean, for proteid food, with nitric acid and ammonium hydrate. The change of the color of the surface shows us that considerable proteid is present. According to the compilations from the government reports, the kidney bean is one of the materials very rich in proteid food. It contains not less than 23 per cent of proteid, 57 per cent of carbohydrates, and about 2 per cent of fats.
Test a bean by heating it on a piece of paper in the oven to see if the small quantity of oil present can be detected by this means.
The above tests show us that the bean seed contains a large supply of food which, as we shall see, is used by the young plant in its germination.
Germination of the Bean, Pea, and Corn.-Soak the seeds at least eight hours in water before planting. In general, the larger the seed the longer the immersion in water before planting. For use in the laboratory seeds may be planted in shallow boxes or trays. Use sawdust, clean white sand, or sphagnum moss to plant them in. Make holes in the bottom of the boxes for drainage. Plant beans about half an inch deep; smaller seeds