The following are some of the many other experiments you might undertake: 1. A test of varieties of corn, oats, and wheat.

2. Treatment of seed wheat, oats, and potatoes for fungous diseases.

3. Planting large and small cuttings of potatoes.

4. Planting potato cuttings, part with the "eye" up and part with the eye down. 5. Planting tip and butt kernels of corn.

6. Planting sound and defective seed corn.

7. A test of frequency and depth of cultivation of corn or potatoes.

1. Get advice from your elders as to best time and manner of doing the work. 2. As far as possible, avoid working the ground when wet. This is very important if the soil is heavy. In early and late planting you can not always avoid this. 3. Try to get the soil well pulverized before planting or sowing.

4. Each one of the older boys should have a memorandum book, in which he should draw a diagram of the plats, and number each one in both series.

5. Under the proper date and number note when and how each plat is prepared and planted.

6. Treat the several plats of a group just alike in all respects except the point under investigation. To illustrate: If you want to learn the effect of planting seeds deep and shallow, take care that the several plats in this group are prepared alike, planted the same day, with the same kind of seed, the same number of seeds, and cultivated at the same time and in the same manner.

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7. Observe when the seeds in each plat come up," the per cent of seeds that germinate, how the young plants look, etc., and make careful notes of these and other observations under the proper numbers and dates in your memorandum book. The chief purpose of this is to acquire the habit of making close observations and carefully recording the same. Your teacher will show you how to make

the notes in your book.

8. From time to time during the season make careful observations, always comparing the several plats of the group with each other, and note in your book the points of interest.

9. Be on the lookout for the first appearance of rust on wheat, oats, rye, and corn. Examine both upper and under surfaces of leaves. Note to what extent each variety is affected by rust.

10. Note what per cent of smutted heads appear in wheat, oats, and rye. Be very careful to note the effect of treatment of seed on the amount of smut present. 11. Note when and where corn smut first makes its appearance, and whether any varieties show more smutted stalks than others. Note how many of the smutted stalks produce no ears. Extend your observations to the fields of corn

near by. By counting stalks in the field with and without smut, and noting the per cent of ears in each lot, you may learn how the proportion of grain is affected by smut.

12. If any plants become sickly or die before they mature, try to find the cause. It is quite likely to be the work of some injurious insect. If you do not look very carefully the little fellows may escape notice. Prove that boys have "sharp eyes" by finding and capturing the culprits.

13. It will be necessary to continue operations on your school farm during the summer vacation. Six or eight of you can do this by taking "turns" on successive weeks. Why not organize a school-farm club and elect one of the older boys director of experiments? If no one of the scholars feels competent to take charge of the experiments, invite some wide-awake, progressive young farmer of the neighborhood to act as director. Your teacher will cheerfully aid you to organize and conduct such a club. You could meet each fortnight at the schoolhouse and compare notes and observations. You would find such a club both interesting and profitable.

14. In performing the experiments many puzzling questions will arise as to principles and methods of cropping. If your school farm does not give you the answers, consult the other leaflets of this series. Consult also your teacher, parents, and others, and if you are not fully satisfied, write to me, and I will try to give you the desired information. I will be glad to hear from you at any time, and will be especially pleased to have you report anything of interest in connection with your school farm.

[FOR THE USE OF TEACHERS.]

No. 2.

LEAFLET

ON NATURE STUDY.

ESPECIALLY ADAPTED TO THE USE OF CHILDREN IN SCHOOLS IN RURAL DISTRICTS.

[Prepared by the faculty of Purdue University.]

THE STUDY OF THE FOLIAGE LEAF.

[By Prof. STANLEY COULTER.]

The materials for "nature" study are the nearest and most conspicuous natural objects. These materials necessarily differ with the locality, with the seasons, even from day to day. It will be found, however, that in almost every locality the greater part of these studies will be connected with plant forms. The reasons for this are very apparent. Plants are living things and life appeals to the child. The material for the studies is convenient and abundant. Plants have a fixed position, allowing the effect of varying conditions to be readily seen and understood. The life cycle is so short that all of its phases may be observed in a single school year. Beyond this it is to be remembered that plants stand as the visible sign of the agricultural capacity of any region, giving us direct report of the character of its soil and climate; that they are intermediaries between unorganized matter and animal forms, and that they have profound economic importance not merely in furnishing food stuffs, but also in some of their forms, in absolutely conditioning public health. It is, however, because of their abundance and rela

tive ease of preservation in any desired condition that plant forms must naturally furnish the material for a large part of nature studies.

The flowering plants are evidently the most conspicuous plant forms in any region, and of these the foliage leaf is the most conspicuous part. From the earliest spring, when it begins to unfold its blade of delicate green, until it falls clothed in autumnal brilliance, it is the dominating feature of the plant. For this reason this leaflet is intended to suggest how the foliage leaf may be used as an object for nature study in such a way that all work done will have a definite purpose and an equally definite value.

Foliage leaves are so variant in general appearance, in position, in size and general outline, that it seems necessary to determine what characters are common to all such organs. The following general characters will be found to apply to all foliage leaves however diverse they may be in appearance:

1. The foliage leaf is a lateral organ of the stem. It is found upon no other part of the plant body.

2. The foliage leaf is characteristically green, due to the presence of chlorophyll, which is developed only in the presence of sunlight.

3. The foliage leaf is an expanded organ, giving the greatest possible surface exposure to light and atmospheric conditions. Other parts of the plants are mass structures, not surfaces.

It is very evident from these common characters that the foliage leaf is an organ adapted for the light relation. The value of this conception of the foliage leaf in nature studies can scarcely be overestimated. Its application readily and clearly explains peculiarities of form, of position, of lobing, and the great mass of adaptations characteristic of plants growing under differing conditions. It explains in a general way plant outlines, and will be found to render clear many apparently puzzling conditions.

Before illustrating the above points specifically, it will be well to consider briefly the work of the leaf. This work may be grouped under four heads:

1. Transpiration, or the interchanges of moisture between the interior of the plant and the external air. The result of transpiration, which is after all apparently little else than evaporation, is to aid in the transfer to the leaves of the nutrient water taken from the soil by the roots.

2. Respiration, or breathing. Those gaseous interchanges between the plant and the air through which oxygen is taken up by the plant and carbon dioxide returned to the air.

3. Carbon fixation, or those processes through which, under the influence of light, carbon dioxide taken from the air is broken down, the carbon being retained and built into the tissues of the plant, while a portion at least of the oxygen is returned to the air.

4. Photo-syntax, or those processes through which, under the influence of the light, the crude food materials derived from soil and air are transformed into substances suited to the needs of the plant.

While for the purposes of this leaflet only one of these uses, that of transpiration, will be considered, the others have been given to show how essential the light relation is to the foliage leaf if it accomplish its assigned work. The foliage leaf then is not merely an ornamental appendage to the plant, its various peculiarities being considered as the result of chance, but a working organ intimately concerned with the most important duties in the individual life of the plant.

Let us now examine some of the ways in which this light relation is secured. One of the forms, often seen, especially in the early spring, is that known as the "rosette" arrangement. The foliage leaves are apparently arranged radially, lying flat upon the ground, and in the absence of the stem, seeming at first glance quite unlike organs for light relation. Common plants with this arrangement are the mullein and plantain. If the leaves in this arrangement are without

leafstalks, it will be found that in almost every case they are broader at the apex than at the base, a form which in definitional botanies is known as spatulate. The successive circles of leaves as they arise from the center are progressively shorter, the broader portions at the apex fitting into the spaces left between the narrowed bases of the leaves of the preceding circle. If the whole rosette be looked at from above it will be seen that scarcely any portion of the lower leaves is shaded by those above, each leaf, by its peculiar form, and the regularly diminishing size of the leaves of succeeding circles, being brought into the most perfect light condition. In the case of the plantain, where leafstalks are present, the same condition is brought about by the progressive shortening of the leafstalk from the lower to the upper circles of leaves. It is very evident, then, that the "rosette" arrangement is a device for securing the light relation on the part of plants with reduced

stems.

Material for illustration: Common plantain, earlier leaves of mullein, shepherd's purse, dandelion.

Taking the cases where leaves are found upon a well-developed stem, the most casual examination will show device after device for securing proper light relations. So evident are they that they need not be mentioned in detail, almost every species of plant furnishing its own solution to the problem. If an ordinary erect stem is looked at from above it will be seen that the leaves are arranged in a series of fairly distinct ranks. The number of these ranks is important, since it has a direct relation to leaf form. The greater the number of ranks the narrower the leaves. The smaller the number of ranks the broader the leaves. Facts evidently explained by our conception of the leaf as the organ of light relation.

Thus far it has been assumed that the leaf-bearing stem has been erect. If by any chance or by the necessities of growth it should change from the erect to the horizontal position, it is evident that to secure proper light relations the leaf position must also change. Comparisons of leaf positions upon erect and horizontal stems taken from the same plant will prove of great value in emphasizing the fact that, above all other things, the leaf must have light exposure.

Material for illustration: Erect and horizontal stems of elm, maple, linn, oak, apple, peach, cherry, catnip, wild pinks, honeysuckle, or of any plant that may be growing near at hand.

I have considered as yet only cases in which the leaves were entire, or with unbroken margins, since these furnished the simplest illustrations. In the case of lobed or dissected leaves, the conditions are somewhat different. In the simpler forms of lobed leaves, the lobing is evidently a device to prevent the shading of underlying leaves. If you recall the ordinary ivy, with its sharply angled leaves, almost geometrical in their regularity, this fact will be evident. If a growing tip of this plant, as it clings to the wall, be carefully flattened down it will be seen that the leaves fit into each other so accurately by means of these angles that on the one hand there is scarcely any perceptible shading, and on the other there is scarcely any space unoccupied by the leaf. Such accurate fitting of leaves when brought to a common plane produce what is known as leaf "mosaics," which simply serve to again prove that the leaf is the organ of light relation. Where the leaves are much dissected, as in the case of the common ragweed, there is the same arrangement in ranks, the same arrangement of leaves in different planes as in the case of the entire leaf, but as a rule no marked diminution in the size of the leaves as we pass from the base to the top of the plant, the constant shifting of the parts of the dissected leaf and the possible play of light through the openings between the leaf parts being sufficient to prevent any portion of the underlying leaf from being continuously shaded.

Material for illustration: Ivy, geranium, star cucumber, begonia, common mallow, ragweed, or any plant with lobed or dissected leaves.

It will be seen, then, that leaf form largely determines the outline of the plant,

taken as a whole. Let us return to the mullein for a moment. It will be remembered that the leaves are entire, the lower ones being the largest and standing nearly at right angles to the stem. As the summit is approached the leaves become gradually smaller, and at the same time more closely appressed to the stem, until at the extreme summit they are much reduced and nearly parallel to the stem. This arrangement, so evidently for the purpose of preventing shading of lower leaves, serves to give to the whole plant a general pyramidal outline, a form characteristic of simple plants with entire leaves. In the case of the ragweed, on the other hand, since there is no diminution in size of the upper leaves, the general outline of the plan is cylindrical, a form characteristic of plants with divided or dissected leaves.

It is evident that in genuine nature work the foliage leaf is to be studied from a new view point. It is not to be used as a frame upon which to hang definitions as tɔ form and margin, apex and blade, but is to be considered as a working organ charged with important duties which can only be successfully performed in the presence of the light. In this view all peculiarities of position and form and structure are but devices for enabling the leaf to properly accomplish its work. The main question in every case concerning the foliage leaf is, "How is the light relation secured?"

Before considering specifically how the view of the foliage leaf as the organ of light relation serves to explain many so-called adaptations to meet special conditions, it is necessary to touch very briefly upon the relation of plants to the soil. It is evident that by far the greater part of the food of the plant is derived from the soil. It is also plain from our knowledge of the structure of the plant that this food must be taken up in the form of a watery solution. It follows, therefore, that the amount of water in the soil has a very important bearing upon the food supply of the plant, and serves, perhaps, more than any other one factor to determine its structural features. Indeed, this matter of the available water of the soil is of such great import that it determines largely not merely the external form of the plant, but also modifies in a marked way its minute structure.

Based upon this dependence of plants upon and their relation to water, the plants of any given region may be separated into three groups, each showing adaptive arrangements to fit it for its place in nature:

1. Water-loving plants, or those plants which live either wholly or partly in water, or else grow in very wet soil, where the water percentage is 80 or above. This is an extreme form of vegetation, and the number of species of plants in this class in Indiana is relatively small. Technically such plants are known as Hydrophytes.

2. Dry soil or desert plants, at the opposite extreme from the water-loving plants. These plants grow in dry soil and atmosphere, the water content of the soil being below 10 per cent at its minimum. Such plants are known as Xerophytes.

3. Intermediate plants, or those adapted to medium conditions of moisture in air and soil. Such plants are known as Mesophytes, and constitute the larger portion of our native flora.

While these differing soil conditions modify the structure of the entire plant, we wish at this time to consider only their effect upon the leaf. It is plain that when a plant lives in an extremely dry soil the water lost by transpiration can be replaced with extreme difficulty, and that if no check were placed upon transpiration the available water in the soil would soon be exhausted and the plant would die. On the other hand, when plants live in the water or in a soil rich in water, the losses from transpiration, however great, can be easily replaced. As the foliage leaf is the chief organ of transpiration, the most evident adaptations to control the process occur in it.

ED 98-100