are fitted to absorb nourishment from the soil, and also, to hold the plant firmly in the ground.

Read "Movements of Seedlings" and "The Birth of Picciola" in Newell's Reader in Botany, Part 1. The Leaves.

What

What becomes of the coat of the seed? comes from the seed opposite the radicle? Examine in the bean and pea (the lima bean is particularly good for this) soaked over night the little leaf bud (called the Plumule) between the two thickened halves or Cotyledons. Study the growth, unfolding and changes in color of the little leaves. How do the leaves of the bean and pea differ? Are the first and later leaves alike? Where and in what position with reference to the first leaves (particularly in the bean) are the later leaves formed? Why? How are the young leaves protected in the seed? In the bud? Notice this latter point particularly in the pea.

What is the use of the leaves? (See the next article on the Study of the Leaves.) The Stem.

Notice the position of the stem as it emerges from the ground. Why is it arched? What mechanical advantage is there in having it push through the ground in this shape? What would be the effect upon the tender plumule if the cotyledons were pushed through the ground tip first, instead of being pulled base first? What has been the effect on the rate and direction of growth of planting seeds in different positions? Does the radicle ever grow upward? Does the stem bearing the leaves ever grow downward? When does the stem straighten itself? Why? What is the use of the stem? When the stem is an inch or more high, mark it as the root was marked, and find whether it grows throughout its whole length. How does its growth differ from that of the root? Why?

The Cotyledons.

When do the cotyledons separate? Do they ever close or partially close again? Examine them in the evening. What changes in their color? In their position? In their size? What becomes of them finally?

Notice the differences between the bean and the pea in these respects. What is the use of the cotyledons-In the seed? To the growing seedling? How is it that bean and pea plants can grow so large on blotting paper, without any earth? (Peas planted on cotton have fully developed and formed flowers.) Flowers and Pods.

If possible, continue the observations until the flowers and pods are formed, so as to have the whole cycle or life history of the plants. Notice position of flowers with reference to the leaves, their formation and development from buds, the parts and changes of the flower, and the formation, growth, and contents of the pod.

What is the special work of the flower? (See accompanying article on the flower.)

Study of Other Seeds.

When beans and peas are two or three weeks old, plant, in the same way, the following seeds: Sunflower or pumpkin or squash. Morning glory or four o'clock. Corn and wheat or oats.

Study their growth and parts in the same way, constantly comparing with the bean and pea and with each other. Notice particularly the number of cotyledons, the changes through which they pass in germination, and the ways in which the food is stored up for the little plant or embryo in the seed, sometimes in the embryo itself (as in the bean), sometimes outside of the embryo (as in the morning glory and the four o'clock).

Miss Newell's Outlines of Lessons in Botany, Part I, will be found very helpful in this study of germination.

THE STUDY OF LEAVES.

CHARLES B. SCOTT, SUPERVISOR OF NATURE STUDY, ST. PAUL.

Editor of Nature Study Department of "SCHOOL EDUCATION."

Leaf study should begin in the early spring, with the study of buds, the protection of buds by scales, stipules, gum, fur, etc., and the arrangement of leaves in the bud. No more interesting subject of investigation can be found than the protection of young leaves and the various ways in which they are folded, rolled, plaited and crumpled in the bud. "Baby Leaves and the Ways in which they are Protected," has been the subject of several very successful field lessons, particularly in the kindergarten and lower grades in the schools of St. Paul. The children have found in the most common plants, hazel, oak, fern, milkweed, violet, sumac, dandelion, wild pea, clover, cranesbill and burdock, a wonderful revelation of protection and care.

Even in early summer the young leaves on the growing ends of many of the plants suggested above and of other shrubs and trees will well repay careful study. The germinating seedlings (see article on Seeds and their Germination) will show how leaves are protected in the seed and during the early stages of growth. Notice in the pea the use of the little green leaf-like parts at the place where the leaf joins the stem (the Stipules), and the way in which the older leaves enclose the younger ones. Notice also how the stronger veins are in the most exposed positions. Equally interesting is the study of the protective movements of the leaves. Study the position of the upper leaves of the common milkweed in the evening and morning and compare with their position during the day. What is the reason for their change of po

sition? Examine clover and other plants, particularly those with compound leaves with small leaflets, for any similar protective movements of the leaves, comparing their position at night or "sleeping position" with their position during the day-time.

Mother Nature is so exceedingly careful in packing and protecting the leaves, they must be of great use to the plant.

Count the leaves on some shrub. Measure the area of three or four leaves and estimate the total area of all the leaves on the shrub. They must have some great work to do. There must be some reason for such an extent of leaf surface.

Notice the arrangement of the leaves on the stem. Look down from above on a milkweed and study the order in which the leaves are arranged. Examine burdock, plantain and other common herbs. Do the leaves have any order, or are they simply scattered without any plan? Study the arrangement of leaves in the maple, elm, linden and other trees. What different kinds or plans of arrangement do you find? Does it improve the appearance of the plant to have the leaves more or less regularly arranged?

Study the position of the leaves with reference to the light. Turn house plants so that leaves face the interior of the room and notice how the leaves turn back to the light. Experiment with bean, pea and other seedlings and find how long it takes the leaves to turn back toward the light. Study very carefully Study very carefully the arrangement of leaves in house plants (such as the geranium) placed near windows. What proportion of the surface of the leaves gets the direct light? What proportion of the leaf surface is covered or shaded by other leaves? Study in the same way some common weeds, such as milkweed and burdock, several shrubs (select those with few branches) and finally young trees, such as the elm and maple. Every leaf is making a great effort to see the sky and sun. Does this struggle for sunlight influence in any way the length of the leaf stalk or petiole? Does it affect the length of the stem or branches of the plant? Does it seem to have any influence in determining the shape of the leaves? (Examine boxelder leaves.)

Dame Nature is so very careful about protecting the leaves; she is so orderly in arranging them; she spreads them out to cover such a large area; she helps every leaf, if possible, to catch a glimpse of the sun; she must have a great work for them to do and the sun must be an important or essential helper in performing that work. What do the leaves do? What is their work or function?

Examine the mullein, burdock, plantain, milkweed and other plants during a shower. Notice the course of the water. As it passes from leaf to leaf is it directed away or toward the middle part or axis of the plant? Study the channels on the leaves and (in

some cases) along the petioles. Have they any effect on the direction or course of the little streams of rain water? Examine the stem of the plant for similar channels. If any are found, note their position with reference to the leaves and their functions. Notice the course of the water in dropping from leaf to leaf. Study the relation between the direction of the rain water (toward or away from the center or axis of the plant) and the arrangement of the roots of the plant. When the water is directed inward, toward the axis, and runs down along the stem, is there any advantage in having a strong central root, or tap-root? Where the water is directed away from the center, so that it drops to the ground some distance from the axis of the plant, is there any advantage in having many roots (multiple roots) spreading in all directions. Study the direction (toward or from the trunk) taken by rain water on different trees, and the reason for its course. (See Newell's Reader in Botany, Part I; article, "Root and Crown.") We find, then, that one function of leaves, in many plants, is to guide the rain water to the roots.

Repeat the experiment in the article on "Seeds and their Germination," showing how the roots absorb water, with food and other matter dissolved in it, and how it is carried through the stem and into the leaves. To keep the plant supplied with food, water must constantly be passing into the plant. What becomes of it?

In order to find this out, break a small branch covered with leaves from a bush and fasten it in a widemouthed bottle fitted with a cork. Drill a hole in the cork large enough for the branch to pass through, cut the cork in half through the middle of this hole and fit the cork closely around the branch. Nearly fill the bottle with water and insert the cork with the branch. Place the bottle on a balance, weigh it, and note the weight. Place the bottle in the sun. In a short time the water will begin to sink in the bottle, showing that the broken end of the stem is able to draw up the water. After it has been a few hours in the sun weigh again. It now weighs much less, showing that the water has escaped into the air. If we now pick off the leaves, the water will practically cease sinking in the bottle. Evidently then the water is escaping from the surface of the leaves, and, as it is not dripping from them, it must be passing off in the form of vapor. (From Laurie's Food of Plants.) Vary the experiment by keeping the plant in the bottle in the shade. How does that effect the rate at which the water passes off? Try the same experiment with a small branch and bottle and cover with a glass vessel, such as a fruit can. What collects on the inner surface of the can? Why? The experiment can be made more effective by placing alongside of the bottle another bottle of the same

size, with the same amount of water in it and covered in the same way, but without any plant in it. From which bottle does the water escape the most rapidly and in which can does the most water collect?

The following experiment (from Goodale's Physiological Botany) is also suggested: "Take six or eight of the largest, healthiest leaves you can find, two tumblers filled to within an inch of the top with water, two empty dry tumblers, and two pieces of card large enough to cover the mouth of the tumbler. In the middle of each card bore three or four holes just wide enough to allow the petiole of a leaf to pass through. Let the petioles hang sufficiently deep in the water when the cards are put upon the tumblers containing it. Having arranged matters thus, turn the empty tumblers upside down, one over each card, so as to cover the blade of the leaves. Place one pair of tumblers in the sunlight, the other pair in a shady place. In five or ten minutes examine the inverted tumblers."

Where and how does the water escape from the leaf? "Pick a fresh, green leaf and lay it lightly back downwards on a polished piece of metal (the lid of a tin can). After a few seconds pick it up again. The metal surface under the leaf is covered with little drops of water, owing to the escaping vapor condensing on the cold surface. Now turn the leaf over and place the front or upper surface on the metal surface. Very little water will now be found. on the metal, showing that most of the water vapor is escaping from the under surface of the leaf." (From Laurie's Food of Plants.) When we examine the under surface of a leaf with a compound microscope we find it to be covered with minute openings or mouths, called breathing pores, or stomata. There are said to be about 100,000 of these on the lower surface of an apple leaf and between 11,000,000 and 12,000,000 on a cabbage leaf. From these the water vapor escapes.

We find, then, that water, containing in solution food for the plant is absorbed by the roots, passes through the stem and out through the leaves, in the form of water vapor. This evaporation of water, or Transpiration, as it is called by the botanist, is another function of the leaves, and explains the great extent of their surface.

To investigate another use of the leaves it will be necessary to study something about the air and the way in which it is vitiated or made impure. Light a short candle and let it down into the bottom of a fruit can. Why does it go out after a little time? Invert a fruit can full of water in a basin of water and, by blowing through a tube with its lower end under the mouth of the can, displace the water in the can with air from the lungs. Close the mouth of the can, kept under the surface of the water in the basin, with a piece of glass or pasteboard, quickly lift

the can from the water and let a lighted match down into it. If the experiment has been properly performed the match will immediately go out, showing that air which has been breathed or burned is unfit to support combustion. We know that it is equally unfit to support life. The oxygen in it has been consumed and a quantity of carbonic acid, formed by combustion and by the vital processes in the body, has been added to it.

Invert a fruit can full of water, in a basin containing water and fill it as before with impure air from the lungs. Push up into the can, without removing

it from the water, a healthy young plant with a number of leaves, leaving the roots of the plant in water, and set basin, can and plant in the sunlight. After 24 hours take the can out of the water as before and test the air in the can with a lighted match. The match will now burn, showing that the plant acting in the sunlight has purified the air, or restored it to its former condition.

Fill a can with water, immerse in the water a leafy stem or a number of leaves and set in the sunlight. Soon bubbles of gas will begin to rise from the leaves. If these are collected it can be readily shown that they are composed of oxygen gas, showing that the leaves, with the aid of the sunlight, throw out oxygen. At the same time they absorb carbonic acid gas.

A second function of the leaves, therefore, is to purify the air, with the aid of the sunlight, by absorbing the carbonic acid which man and other animals, and also all burning things, are constantly throwing into the air, thus rendering it unfit for the support of combustion and life, and, at the same time, throwing out oxygen gas, which is necessary for the support of combustion and life.

Examine plants which have been kept in the cellar or away from the light; look for grass or other plants which have been covered up from the light by boards, stones, etc. How does the color of the leaves in such plants compare with those growing in the sunlight? The green color of leaves and other parts of the plants is due to the presence in them of chlorophyll (meaning leaf-green), which is made with the aid of the sunlight. This chlorophyll makes, from the water coming from the roots and the carbonic acid. gas absorbed through the breathing pores, starch, which is the principal food of the plant.

The leaves of plants, then, have still another function. They are the food-making laboratories, or organs of assimilation of the plant.

Now we are ready for the study of the structure of the leaf; in fact we have already, almost unconsciously, studied most of the essentials of structure.

Note (in an apple leaf) the divisions of a complete leaf, the broad expanded part or blade, the stem or stalk or petiole, the small leaf-like projections at

either side of the lower end of the stalk, the stipules. Study their modifications in different plants? Can you find any reasons for these modifications? (For various forms of leaves see any botany.) Study the different plans of arrangement, the endless variations in the form of leaves, and the absence or presence and varying length of the petioles of leaves, with reference to the uses of leaves and the fact that they must get the sunlight. Endeavor to replace the leaves on a branch of one tree, as the maple, with those from another, as the elm. How do they fit? There is endless opportunity for investigation along this line. (See Lubbock's Leaves, Flowers and Fruit.)

Study the structure of a plantain, or burdock leaf. Notice the skin, or epidermis, covering both upper and lower surfaces of the leaf and the green pulp, parenchyma, between them, where the work of assimilation is done. Notice the fibers forming the core of the veins, at the lower end of the leaf stalk, where it is broken from the plant. Trace these fibers up into the blade of the leaf and notice the way in which they subdivide and branch. Are the veins well arranged to carry water and food to all parts of the leaf? Are they well arranged to support the leaf? Notice in maple, oak and other leaves the relation of the veins to the irregularities of the margin. Why are they arranged as they are? Compare the veining of the maple with that of the oak or burdock; in the maple there are several principal veins starting off from the upper end of the petiole (palmately veined); in the oak there is a single long central vein and the others branch from the side of this (pinnately veined). Considering the veins, both as the supporting system (frame-work) and the conducting system (blood or sap vessels) of the leaf, is there any advantage in having roundish leaves, like the maple palm

ately veined, and longer leaves, like the oak, pinnately veined?

The study of the leaves may well be continued in the fall by investigating the fall of the leaves. Why -from the standpoint of the tree-do they fall? Are they of any further use to the tree? Are they of any use after they fall? What is the mechanical reason for their separation from the trees? Compare the maple, box-elder and sumac leaves in this respect. In the box-elder the leaf stalks often remain on the trees all winter. Why? Examine their base. Why do the oak leaves remain on the tree in some species all winter? What makes them fall off in the spring? Why do the leaves usually change their color in the fall? Is there any other reason than the aesthetic one-to make them look pretty?

The writer wishes to acknowledge his special indebtedness, in the preparation of this paper, to Laurie's Food of Plants, for many experiments on the uses or physiology of leaves.

Flowers and their work.

There is not room for the treatment of this subject in this number. The work of flowers in making seeds can be well studied in the fall; that subject, together with the dissemination and protection of seeds, will be treated in the numbers of SCHOOL EDUCATION for September and October,

The evening primrose and the dandelion will be found exceedingly well adapted for the summer study of flowers and seeds. Both show all stages of development at the same time. The student of nature who carefully observes these, and particularly the dandelion, who is not content with simply picking them apart and examining their structure, but constantly asks "Why?" "How?" will learn from these many of the most wonderful secrets of plant life.

20c. Other 43 pages. 20c.

XIII.

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If the method be right, it does not matter, among the numerous subjects well fitted to develop this important faculty, which he choose, or which be chosen for him."

In looking over nature's store-house, it seems to me, that, in all her three kingdoms, no fitter objects can be found for the training of this observational power than "the trees." They are to be found everywhere; scarce a city block, a village square, or a country farm but that affords specimens of various kinds of these the largest and longest-lived of living things. They are to be found at all seasons in good condition for study; the foliage of many-the evergreens-remains throughout the year, and the very changes which the seasons produce in the deciduous trees, furnish some of the best lessons in observation.

In order to illustrate how much of variety there is to be found in the fifty kinds of trees occurring in almost any locality in the north-western states, I will give what might be used as an

OUTLINE FOR TREE STUDY.

Leaves.-Parts, arrangement, kinds, size, thickness, color, surface, form, edges, veining, duration. Sap and juice.-Watery, milky, sweet, bitter, mucilaginous.

Buds.-Size, form, covering, number, position
Forms and sizes of trees.
Twigs and branching.

Bark.-Thickness, roughness, looseness, color. Wood. Hardness, weight, color, grain, durability. Flowers.-Size, shape, color, position, odor. Fruit. Size, form, color, hardness, usefulness. Brief remarks on the above outlines: Leaves and parts.-Few people who have not studied the matter know that there are any parts belonging to leaves, except the blade and the stem; but many leaves have, at the base of the stem, small blade-like parts, called stipules. These are well shown in the quince. On some kinds of trees these stipules are very large, and drop as soon as the leaves expand, as in the magnolia; other large ones hang on for a time, as in the tulip-tree. On the oaks, the

stipules are quite small and drop early, while in other trees they are wanting. In some leaves the stem is long as compared with the blade; in others very short, and in still others there is none at all. The poplars have long stems, and some of the species have them peculiarly flattened, making the leaf tremble in the slightest breeze. The stems of the oak leaves are, in most species, very short; many of the evergreens have no stems at all.

Arrangement.-Leaves are often arranged in pairs on opposite sides of the twig, as in the maple, while on the catalpa, though usually opposite, they are frequently placed in whorls of threes around the twig. The leaves of most deciduous trees are alternately arranged. This is true of the apple, the oaks, the willow, etc. The pines have their leaves in bundles of two to six; the larch in much larger clusters. In the cedar and the arborvitæ the leaves are closely pressed against the twigs, while as a general thing, leaves spread quite squarely from them.

Kinds.-Leaves of trees are usually, though not always, simple, i. e. have but one blade. The horsechestnut has about seven blades, all branching from the end of the leaf stem, while the common locust, sumach and ash, have many blades, spreading like a feather from many points. In the honey locust, the leaf is divided, in a feather-like way, twice; in this species, the blades sometimes number more than three hundred to a single leaf. The leaves of the horsechestnut are said to be palmately compound, while those of the locusts are called pinnately compound.

Size. The leaves of some trees are several feet long, while those of others are not over an eighth of an inch in length. The ailanthus, or tree of heaven, has the largest leaves of any tree in this section, while the white cedar has the smallest.

Thickness.-There are great differences even in the thickness of the blades of leaves; thus, the laurel, boxwood and oaks have thick leaves, while the sweet birch and beech have thin ones.

Color.-The grades of color between the extremelydark leaves of the Norway spruce, the ash, etc., and those of the white willow and white poplar are very great, and add much of beauty and variety to any landscape dotted with trees. This is true even during the summer, when all the coloring is in some shades of green-bright green, bluish green, grayish green, etc. But it is the bright, glowing autumnal tints of the leaves that reveal the trees to us in all

their magnificence. The intense yellows, reds, browns, and other shades of the maples; the whitish, orange, violet, purple and brown of the oaks, are but a few of the brilliant tints which give our forests their greatest variety and splendor.

Surface. The differences in surface are also well worthy of study. The smoothness of the chestnut,