M509 Ube Ylbtamt Bulletin SERIES VIII DECEMBER, 1909 Number 6 OHIO STATE NORMAL COLLEGE PUBLICATIONS TEACHERS’ BULLETIN No. 11 The Soil and Its Relation to Plants B. M. DAVIS Published Monthly by Miami University And entered at Postoffice , Oxford , Ohio , as Second Class Mail Matter SECOND EDITION. The first edition of Teachers’ Bulletin, No. 1, of the De¬ partment of Agricultural Education of the Ohio State Normal College, Miami University, Oxford, Ohio, published in May, 1907, was soon exhausted. The large number of requests for copies and the many encouraging letters from teachers who have used the bulletin seem to justify a second edition which is now presented in its revised form. F. L-. sr Ie.5 THE PLACE OF AGRICULTURE IN PUBLIC SCHOOLS. During the last few years there has been earnest discus¬ sion as to the desirability of having instruction given in our elementary schools, particularly in those of rural communities, involving some of the fundamental principles of agriculture. It is now generally admitted that such instruction is desirable, and the general attitude of those interested in education is fav¬ orable toward it. (18, 19)* In Ohio and other places, where the subject is not re¬ quired to be taught, there is some hesitancy on the part of the teachers toward introducing it into their schools. Although they may believe in it, the teachers do not see quite clearly how to find a place for it. Furthermore, they do not know just how to make a start, for it is a new and unfamiliar sub¬ ject. Not being able to find a place for it is not 'a valid objec¬ tion. Although the course of study may appear to be over¬ crowded, much time and efficiency would be gained by atten¬ tion to two important particulars which are now lacking for the most part in most schools, viz.: (1) practical application of the formal subjects; (2) forms of school activity other than the formal preparation and recitation of lessons from text¬ books. Some subject is needed which involves in a concrete way some practical use of arithmetic, written language, and reading. Hypothetical problems, many of them having only the remotest application to the life the pupil will lead, essays using sentences which are empty of all thought, reading which is but the mechanical calling of words, these are faults which have inevitably crept into our schools, and which every true teacher deplores and tries to correct. Certain phases of elementary agriculture deal with com¬ mon and familiar facts which should have meaning and sig¬ nificance to every country child. But the very handling of * Figures refer to references on pp. 32-33. 3 these familiar facts in such a way as to reveal their meaning involves the use of the formal studies as tools. Thus elementary agriculture should have a place in the country school in order to. secure the best and most practical results from the subjects already being taught there, and also in order to secure the best reaction of the school on the community. But the subject has a great importance of its own which is considered by many sufficient to justify its introduction. This point of view is seen from the following aims of the sub¬ ject as set forth in the manuals of the elementary course of study of two of our most progressive agricultural States: “1. To cultivate an interest in and instill a love and re¬ spect for land and the ocupation of agriculture. 2. To create a regard for industry in general and an ap¬ preciation of the material side of the affairs of a highly civilized people. 3. To cultivate the active and creative instincts ‘as dis¬ tinct from the reflective and receptive that are other¬ wise almost exclusively exercised in our schools. 4. To give practice in failure and success, thus putting to the test early in life the ability to do a definite thing. 5. To train the student in ways and methods of acquir¬ ing information for himself and incidentally to ac¬ quaint him with the manner in which information is originally acquired and the world’s stock of knowledge has been accumulated. 6. To connect the school with real life and make the value and need of schooling the more apparent. 7. As an avenue of communication between the pupil and the teacher; it being a field in which the pupil will likely have a larger bulk of information than the teacher, but in which the training of the teacher can help to more exact knowledge.” (Course of Study for the Common Schools of Illinois, 1907, pp. 207-208.) “The stress which is being placed upon the practical in education is indicative of a new attitude toward education in general. Instead of emphasizing the knowledge side of edu- 4 cation we begin to recognize the fact that what a man is and what he can do are more important than what he knows. By making scientific nature study and agriculture a part of the curriculum, habits of scientific thinking may be ac¬ quired, a love of nature developed, and the practical work will make the student a more useful member of society. If we admit that education should aid in preparing the child for life, we readily see how necessary it is that the child’s training be of such a character as to adapt him to his environment.” (State Manual and Uniform Course of Study for Elementary aud Secondary Schools of Indiana, 1909, p. 107.) PURPOSE OF BULLETIN. Most of the exercises outlined in this bulletion represent work that has actually been done by pupils of the sixth to eighth grades. Part of the work was done by pupils of the Country Model School No. 1, Ohio State Normal College, an ungraded district school enrolling about twenty-five pupils, in Oxford Township, Butler County, Ohio. The bulletin is intended to encourage and assist teachers who wish to introduce elementary agriculture into their schools and do not know just how to begin or how to con¬ duct the instruction. The subject of the soil and its relation to plants is taken up partly on account of its fundamental importance in farm practice, and partly because it represents fewer difficulties in the way of experimental study to be carried on by pupils of the grades or of the first year of high school. Furthermore, it is one of the few phases of the subject of agriculture that may be studied to advantage during the winter. Indeed, ex¬ perience has shown that such work as suggested in the fol¬ lowing exercises offers a practical solution for the problem of school management during bad weather. SUGGESTIONS TO TEACHERS AS TO METHOD. The following exercises present concretely, in the form of simple experiments, fundamental facts concerning the soil and its relation to plants. Each exercise helps to give meaning, directly or indirectly, to some essential of plant growth. Many 5 of them will at once suggest reasons for some of the most common practices in successful farming. The account of the plant and its work (pp. 6-8 and Fig. )) is intended to give the teacher a short but general perspective of the plant in all its relations. Most of the exercises are intro¬ duced by a brief note of explanation. An account is then given as to how the experiment or demonstration should be conducted and attention is called to the points to be observed. Under Application, is mentioned familiar facts or practices which the observed results help to explain. Each subject should be presented to the pupil as a prob¬ lem. The nature of the problem is suggested in the title of the exercise, and its connection with previous work, or with other problems is indicated by the explanation. Suggestions should be made to the pupils as to how to proceed to get an answer to the problem. It is important for each pupil to do every¬ thing he can for himself. For example, the rack in Exercise XI (Fig. 3) was made by the pupils of the model district school No. 1, and the apparatus was set up by them. The few pieces of simple and inexpensive apparatus may be provided at the beginning of the course. The reference books and pamphlets should also be secured at this time. The pupils should be encouraged to write for and thus obtain the government and state publications for themselves. If the en¬ tire list of apparatus or references can not be afforded, get what seems to be the most important. But much of the work may be done without any expense whatever. If, for any reason, the entire series of exercises can not be undertaken, the teacher is advised to have the pupils try a few, so as to make a beginning. Finally, the writer will gladly reply to inquiries from teachers concerning any points in the bulletin not clearly un¬ derstood. THE PLANT AND ITS WORK. Any intelligent effort to grow plants must, first of all, take into consideration the needs of the plant. In order to understand these needs, the work of the plant in all of its most 6 t important relations to sunshine, air, soil, and water must be known. For the plant to live and thrive it must have sunshine, oxygen, food, and protection from its enemies. The problem of plant-rearing is to provide these essentials for its growth. The animal must rely on food already elaborated into complex compounds, such as proteids, starch-like substances, and fats. The plant, on the other hand, by using the energy of the sun, is able to make these substances for itself from the raw materials such as carbon dioxid, water, and mineral salts. The work of the plant is divided among the plant organs: leaves, stem, and roots. The leaves make most of the food; the stem supports the leaves and carries material to and from the leaves; the roots hold the plant in place, absorb water and the mineral salts dissolved in the water, and receive in return food from the leaves. Water exists in the soil in thin films around the soil par¬ ticles ; that is, apparently dry soil may contain enough water in this state to support a plant. A special set of organs for removing water from these surface films is found on all the smaller rootlets of the plant. These organs are called root- hairs. So far as supplying the plant’s needs is concerned, the most important part of the problem is to secure proper soil relations for the root. In most cases if the plant is not shaded the proper light relation is secured without further attention. There are, however, special cases where the leaf exposure of larger plants needs to be modified by pruning, or where deli¬ cate plants need to be protected from too strong sunlight by partial shade. Securing proper soil relations for the roots of the plant being the chief problem in plant-rearing, it will be necessary to notice what this means. The most important factors are as follows: The soil must contain sufficient mineral salts for the plant's use. The most important of these are the ones con¬ taining nitrogen, phosphorous, and potash. The use of ferti¬ lizers is intended to supply these salts where they are not in sufficient quantities in the soil. 7 There must be plenty of water accessible to the roots in the form of films around the soil particles. The amount of water which a given area of soil will hold depends upon the surface extent of these particles. The extent of this surface, in turn, depends upon the size or state of division of these particles—the more finely divided, the more surface, and con¬ sequently the greater water-holding capacity. Too finely Diagram of a plant showing its most Important relations: sunlight, moisture, oxygen, and soil. 8 divided soil particles, however, will not leave enough space for oxygen to supply the roots; for roots, like all other parts of the plant, must have a constant supply of oxygen. Too much water also will cut off the oxygen supply from the root. The soil in this condition is said to be “water-logged.” The living plant in its various relatons may be seen more clearly by a study of Fig. 1. The directions of movements of the vari¬ ous substances in the plant, and to and from the plant are indicated by arrows. EXPERIMENTAL STUDIES OF THE SOIL AND ITS RELATION TO PLANTS. I. The Root System of a Plant. Explanation: By root system is meant the entire group of the roots of a plant. Root systems are of two kinds: (a) Tap-root: central main root with smaller roots radiating from it. (b) Fibrous: many roots of nearly the same size. (Fig. (b) Fibrous: many roots of nearly the same size. Roots of either of these may be modified, as for ex- which is a modified tap-root, and by the sweet potato, which is a modified fibrous root. Demonstration: (a) Dig up a clover plant and remove the soil from it. Observe that it has a strong central root which joins the stem. Note arrangement and extent of smaller roots which are connected with this main root. (b) Dig up a single grass plant (wheat will do) with as many of its roots as possible and remove the soil from them. Observe that the root system is composed of many roots about the same size. They project from the conical portion of the stem of the plant just below or at the sur¬ face of the ground. (c) Dig up a number of common plants. Determine which have tap-roots, and which have fibrous roots. Make a list of common plants classified as to character of their root systems. 9 II. Extent of the Root System of a Plant. Explanation: In the preceding exercise the root systems of a number of different kinds of plants were examined. The funda¬ mental fact common to both types of root systems is the provision made for root surface (p. 8). The importance of root surface cannot be too strongly emphasized. The amount of food material brought to the plant by the roots must vary according to the extent of these roots; the greater the total root surface the greater the absorbing capacity. An interesting problem in this connection would be to find out under what circumstances this ob¬ ject is best secured by tap-roots and by fibrous roots. Determination of root surface or extent: The amount of root surface of a plant may be roughly determined by measuring the roots and finding their total length. Select some plant (a corn plant will do) which is grow¬ ing by itself. Carefully dig a trench around the plant to a depth of twelve or fifteen inches. The central ball or cylinder of earth will contain most of the roots. Remove by digging as much of the soil from the roots as possible and remove the rest by washing. Before removing the plant note direction of growth, whether branched or not, in what part of soil most numerous, how near the sur¬ face the roots come. All these observations should be put together in a sort of diagram. Remove the plant, saving all the roots. Measure each one and find total length of all the roots. Note: With the best of care it will be impossible to remove all the roots. The real extent will be much larger than the calculated amount. The total length of all the roots of a well developed corn plant has been estimated to be over 1,000 feet; the total length of all the roots of a mature squash vine has been found to be about 15 miles. (1, pp. 207-217; 3, pp. 9-22; 16.) Application: While the object of this exercise is to furnish a con- IO crete illustration of the great extent of the roots of a plant in soil, and furnish a basis of appreciation of the relation of the root to the soil, it has an obvious practical lesson. Methods of cultivation should take into account the fact that many of the roots, especially late in the growing sea¬ son, are near the surface. Deep cultivation will destroy all such roots and to that extent cut off the food supply of the plant, thereby lessening the yield of the crop. (12, p. 4.) III. Root-Hairs. Explanation: The root-hairs are the absorbing organs of a plant, i. e., they transfer the water and the substances dissolved in it from the soil to the rootlet. (Fig. 1.) Demonstration: Put some seeds (radish or wheat seed) that have been soaking in water for about twenty-four hours, between two layers of cotton or cotton cloth (newspaper or blot¬ ting paper will do). Keep the covering moist. In two or three days roots will develop and will be covered with a thick fuzz of root-hairs. Observe the extent of the zone of root-hairs. Note also the length of those near the tip of the rootlet compared with the length of those at the opposite end of the root- hair zone. Select a seed having a straight root and put it on a piece of moist blotting paper. Mark with pencil the two extremes of the root-hair zone. Put away for several days, being careful to preserve the moisture (cover with inverted tumbler) and also being careful not to disturb the position of the root with reference to the marks. At the end of three to five days (a longer time if temperature is low) the root will have increased in length and with it the extent of the zone of root-hairs. The long hairs at the mark nearest the plant, however, will show signs of collapse. In a few more days they will begin to shrivel up. Thus new root-hairs are formed at the tip of the root while the old ones shrivel up and disappear. The root-hair zone is always about the same length. New hairs are formed about as fast as the old ones shrivel up, so that the tip of the root is always followed by the zone of root-hairs. In this way new feeding areas are constantly supplied to the root. (1, p. 146.) IV. How the Soil Holds the Water. (Capillary attraction or Capillarity.) Explanation: When a pencil is dipped in water a film of water ad¬ heres to it. This attraction of a solid for a liquid is called capillary attraction or capillarity. A few simple experiments will make clear this action. Demonstration: Set two square or rectangular pieces of glass in a pan of water, putting the two vertical edges together so that the pieces of glass will form an angle of five or ten degrees. Note that the water in the narrow portion of the angle rises some distance above the level of the water in the pan. Here the capillary attraction is greater than gravity, for it is sufficient to draw the water upward for a short dis¬ tance. The same may be shown by means of glass tubes of different diameters. The water in the tubes having the least diameter will rise to the greatest height. A lamp-wick carrying the oil upward to the flame is another and more familiar example. Application: Root-hairs are adapted for taking up water that adheres to soil particles. (Fig. 1.) This fact is fundamental. It must be kept constantly in mind in all considerations of the soil where the growth of the plant is concerned. The soil may be perfect as to food content and other particu¬ lars, but if the water does not exist as capillary water, i. e. as films adhering to soil particles, the root-hairs are unable to do their work. (1, pp. 136-142; 12, p. 6.) 12 V. How Water Gets Into a Root-Hair. Explanation: The root-hair may be considered as an elongated bag filled with a liquid denser than water. When two liquids of different density are separated by a membrane the less dense liquid tends to pass through the membrane more rapidly than the more dense liquid. This produces a greater pressure on the side of the membrane which is in contact with the liquid of greater density. The pres¬ sure thus exerted is known as osmotic pressure. The whole phenomenon is called osmosis. (1, pp. 147-153.) Demonstration : Material: A wide-mouthed bottle, an egg, a quarter- inch glass tube six inches or more in length, a piece of candle one-half inch long, a wire somewhat longer than the glass tube. Preparation: Crack the large end of the egg and remove part of the shell being careful not to break the shell membrane. The shell should be removed from an area of about one-half inch in diameter. Remove the shell from the small end over an area equal to diameter of glass tube. Bore a hole through the piece of candle just big enough to receive the glass tube. The position of the hole should correspond to the position of the wick in the candle. Heat the end of the candle and stick it over the small end of the egg so that the hole in the candle lies just over the hole in the shell. With a hot wire melt the edges of the candle so as to fix it firmly to the egg. Place the glass tube in the opening of the candle and with the hot wire make the joint water-tight. Break the egg membrane of the small end of the egg by passing the wire into the egg through the glass tube. Now fill the bottle with water and place the egg on the bottle so that the exposed egg membrane of the large end remains below the surface of the water. Action: In about an hour the white of the egg will be seen ris- 13 ing in the glass tube. The water from the bottle passes through the egg membrane and pushes the egg contents into the tube. VI. Action of Water in Soil Formation. Explanation: The chief factor in soil formation is water. The erosive action of water during and immediately after a shower is familiar to everyone. On a large scale the same action is involved in wearing away the mountains and carrying the material to lower levels where it is deposited in the form of soil. It is important in teaching this subject that all phases of this action, which extends over large areas, should be brought into view at one time. The child sees things as wholes and it is difficult, if not impossible, for him to make up a complete picture from fragments. The following demonstration,which may be prepared and set up by the pupils themselves, is intended to show the whole series of erosive processes at work in one picture. It not only shows the actual process of soil making but illustrates many important facts of physical geography. Apparatus: Three boxes, each about three and one-half feet long, one foot wide and six inches deep, are needed. These should be hinged together in a series. Strips of leather the width of the box will answer very well for hinges. Arrangement of apparatus: The next step is to arrange the sections so that they will stand at different levels. The first one should be level; the second inclined about fifteen degrees; the third in¬ clined about thirty degrees ; Strong props must be used to hold the second and third sections in place. The appa¬ ratus as set up is shown in Fig. 2. The sections must now be made water tight. If they are set up out of doors they may be made sufficiently free from leaks by stopping the openings with wet clay. Some provision must be made to carry the water from the upper section to the second section, and from the second to the 14 FIG. 2 Apparatus for demonstrating various phases of erosion. This is a picture of apparatus as set up in the country model school No. 1 of the Ohio State Normal College. FIG. 3 Apparatus for demonstrating percolation and capillary action of different soils. first. Short strips of oil cloth or tin extending over the joints will answer this purpose. If the apparatus is to be set up in the schoolhouse more care must be taken to pre¬ vent leakage. The best way will be to line the entire length of the trough with a strip of oil cloth twelve feet long and two feet wide. At the lower end gather up the oil cloth so as to form an outlet to carry away the surplus water. After the apparatus has been set up according to either of the above methods the second or middle section should be filled with sand, and the upper section with clay. The clay of the latter may be made to vary in hardness in dif¬ ferent places by mixing it with sand. The lower section should be empty. A bucket of water placed above the highest point of the upper section and a siphon made of small rubber hose completes the apparatus. Action of water: Start a small stream of water from the siphon and al¬ low it to trickle down the entire length of the trough. “The clay mixture in the upper section will behave in the same way as rock (only the action will be more rapid), and will show clearly how rock is sculptured by running water, how masses of it become detached and fall ofif, and how as these are carried down stream they lose their sharp edges.” “In the second section we will see land¬ slides, terraces, meanders, oxbows, bubbling springs (where an obstacle occurs), and all other features of stream action. In the third section we shall see alluvial fans and cones, deltas, beaches, the deposit of coarse ma¬ terials near shore, and finer materials further out and all the features of lake and ocean formations.” *(1, pp. 1-54; 2, pp. 47-60.) VII. Soil and Subsoil. Explanation: In a climate such as we have in Ohio the surface of the earth to a depth of from six to twelve inches is called * Osterhont’s "Experiments with Plants,” pp. 110-lU. 15 soil. Below the soil is the subsoil. According to King this distinction “grows out of the fact that oftentimes when the deeper soil is brought to the surface, it is found unproductive for a time, and, besides, there is a sharp line of demarkation of color of the two portions.” (1, p. 29.) Demonstration: The sides of a trench or steep bank of a road will fur¬ nish a good illustration of soil and subsoil. It will be necessary to scrape off an inch or more of the surface so as to expose the soil and subsoil. The soil may be easily recognized by its dark color. All below is the subsoil. Where no such situations are available the same facts map be shown by digging a hole or trench to a depth of eighteen inches and examining its sides as above in¬ dicated. Collect a sample of the soil (a large handful) for use in the next exercise. VIII. What Soil Is Made Of. Explanation: Soil is a mixture of sand (rock fragments), fragments of organic matter (animal and plant refuse), and finer particles known as silt or clay. The amounts of these vary with different soils. Demonstration: (a) Examine a small amount of the sample taken in previous exercise. Note different sizes, shapes, and gen¬ eral appearance of particles. (b) Put enough of the soil in a six- or eight-ounce bottle to fill to a depth of one and-one-half inches. Fill the bottle with water, cork and shake vigorously for one minute. Allow the mixture to settle and watch the pro¬ cess. Note the kinds of particles that reach the bottom first, what next, and so on. Set away until the next day. There will then be seen several layers of material as fol¬ lows : coarse sand on bottom, fine sand next, silt above this, and clay on top. Floating on top of the water and perhaps lying on top of the clay may be seen some dark particles. These are organic materials or humus. 16 IX. Kinds or Types of Soil. Explanation: In the previous exercise attention was called to the fact that the sample of soil was made up of material of dif¬ ferent kinds: sand, clay and humus. As all soils are com¬ posed essentially of these three materials mixed together in various proportion, it is important to know the chief properties of each type. Material: For this and some of the subsequent exercises a supply of each type of soil will be necessary. About one gallon of each will be enough. The important thing is that each kind of soil should be as pure as possible. Sand may be obtained froui the sand bars of any brook or creek. It should be washed thoroughly to remove the clay and other impurities. The washing is done by stirring the sand in a bucket of water and then pouring off the muddy water. Repeat until the water comes off clear. Clay may be found almost pure in the subsoil in many places. The steep bank of a “cut” in a road often has a streak of nearly pure clay in it. The clay should be dried and then pulverized. Putting small quantities of clay at a time in a cloth bag and pounding it is the most con¬ venient method. Humus may be found at the base of a rotten stump or under a rotten log. Avoid large pieces. The fine black material is most desirable. Each kind of soil should be thoroughly dried and kept in a dry place. Demonstration: General characters: Examine a small quantity of each type and compare with observations of Exercise VIII. Behavior toward water: (a) Take about one cubic inch of each kind of soil and add enough water to make a plas¬ tic mass. Note any changes in appearances or behavior while the water is being added. Compare the effect of water on the three kinds, especially as to changes of color and resistance to handling (i. e. relative tendency to be¬ come sticky). 17 (b) Mould each kind into a ball and put away to dry. When dry note the effort necessary to crush or break up the balls of each kind. (c) Fill three shallow boxes level full (baking powder can-lids will do), one with humus, another with sand, and the third with clay. Add enough water to thoroughly saturate each. Set aside until the water evaporates, leav¬ ing the soils dry. Note how long it takes for each to be¬ come dry and also the amount of shrinkage in each. Application: This exercise shows that clay is responsible for many of the difficulties of handling soil, e. g. tenacity, retention of water, baking, cracking, etc. Many of the problems of soil management are really questions of how to deal with clay. When a soil is made easier to work its texture is said to be improved. Good soil texture is quite as im¬ portant as its content of plant food. (1, pp. 96-98; 9, pp. 11-13.) X. How Clay May be Modified. Explanation: The tenacity of clay and some other of its objectional features are due mainly to the small size of its particles. Any improvement of clay must take this into consider¬ ation. The purpose of this exercise is to show some ways of separating its particles, thereby improving its texture. Demonstration: (a) Effect of mixing coarse organic material on the texture of clay. Take four samples of clay (equal quantities) ; mix No. 1 with one-fourth its volume of coarse humus, No. 2 with one-third its volume, No. 3 with one-half its volume, and keep No. 4 as a control. Add enough water to each to form a stiff plastic mass. Note the effect of the humus on the tenacity of the clay. Mould each into a ball. When it has hardened and become dry, test hardness and resist¬ ance by breaking. (b) Effect of lime on the texture of clay. To each of four samples of clay (weighing about 100 18 grams) add the following amounts by weight of slacked lime: No. 1, 1 per cent; No. 2, 5 per cent; No. 3, 10 per cent; No. 4, none, using it as control. Mix each thoroughly so that the lime may be evenly distributed, and add just enough water to make a plastic mass. Mould each into a ball and allow to dry thor¬ oughly. Test the resistance of each by dropping upon a brick or other hard surface. Beginning with No. 3, drop it from a height of 2, then 4 inches, and so on, noting the distance through which it must fall in order to break. Try Nos. 2, 1, and 4 in the same way. The distance through which the balls must fall in order to break will indicate their relative tenacity. Further tests may be made by noting the ease or difficulty in breaking or crushing the fragments of each kind. The lime has changed the texture of the clay and made it less tenacious. (c) Action of lime on clay. The action of lime in producing the above modification of clay is probably due, at least in part, to flocculation, i. e. bringing the smaller particles together to form com¬ pound particles. This may be demonstrated as follows: Weigh out .2 grams slacked lime, place in a tumbler and add 200 cubic centimeters of water (better use rain water.) Put the same amount of water in another tumb¬ ler for control. Now add to both tumblers of water 1 gram of powdered clay. Stir the contents of both and allow to settle. In the one to which the lime has been added flakes or masses of material will be seen. The effect of the lime has been to flocculate the clay. After 24 or 48 hours, when the particles in both tumblers have set¬ tled, examine the sediment. The sediment in the tumbler to which the lime has been added will be granular while the sediment in the other will be finely divided. (d) Effect of burning on clay. Put a piece of clay in a hot fire and burn it for sev¬ eral hours. When cool, if it has been heated enough, it will break easily and show very different properties from unburnt clay. 19 Application: The experiments performed in this exercise give mean¬ ing to some common farm practices. The use of coarse barnyard refuse on soils where clay predominates not only adds fertility (available plant food) but also improves the texture of the soil by separating the fine particles. Lime not only acts as a fertilizer and serves to neu¬ tralize in some instances the acid in the soil but helps make the clay soil easily worked. Lime is applied at the rate of about twenty bushels to the acre once every four or five years. When wood was plentiful it was the practice in some places to improve clay soils by burning. It must be understood that these methods are only ef¬ fective when the soil is well drained. The behavior of clay and other soils toward water will be shown in the next two exercises. (3, p. 42 ; 7; 22 ; 23 .) XI. Flow of Water Through Different Kinds of Soils. Explanation: There is a great difference in soils in their behavior toward the water that falls on their surfaces. In some soils the water is taken up so readily that shortly after a shower very little evidence of rain is noticed. In others, after the rain, water stands in puddles and it is some time before the water disappears from the surface; even then the soil is soggy or muddy. How the character of the soil affects its power to take in water that falls on its surface, may be shown as follows: Apparatus: Four student-lamp chimneys, a rack to hold them, and a pan or four tumblers to catch the water that drains from the tubes. (Instead of student-lamp chimneys ordinary lamp chimneys may be used.) Arrangement of Apparatus: Tie pieces of cheese cloth over the small ends of the chimneys. Fill them nearly full respectively of dry sand, 20 dry clay, dry humus, and dry garden soil (loam). Place tubes in rack. The apparatus as set up is shown in Fig. 3. Demonstration: Pour water into the upper ends of the tubes until it drips from the lower ends. It will be seen that the humus and sand take in water and allow it to flow through quite readily, the garden soil less readily, and the clay quite slowly. Repeat the experiment, using dry garden soil and two tubes. Pack the soil tightly in one and leave it loose in the other. The water will of course penetrate the loose soil much more readily than the other. Application : These two experiments show that the power of soil to take up water depends upon two things: the size of the soil particles, and the compactness of the soil. Clay and compact soils take in water so slowly that most of it runs off and is lost. But as it runs off it carries away some surface soil leaving the surface irregular. The texture of such soils may be improved by keeping them open by plowing (fall plowing) and tillage, thus in¬ creasing their water-holding capacity. The texture may be further improved by methods indicated in the last ex¬ ercise (coarse barnyard material, lime). (1, pp. 157-162; 2, p. 68; 8, p. 9.) XII. How Water Moves Upward Through Different Soils. Explanation: Attention has already been called to the phenomenon of capillarity or capillary attraction. (Ex. IV.) Water exists in the soil chiefly (a) in the form of capillary water i. e., water around soil particles and at the points of con¬ tact between the particles; and also (b) as free water, i. e., water that completely fills all the spaces between the soil particles. In the upper layers of the soil the water exists as capillary water; in the deeper layers it exists as free water. The level of the free water is known as the water table. If a hole be made in the ground, as for example a well, the water will rise to a certain level; this 21 level is the water table. The position of the water table varies with the season, being influenced by rainfall, at¬ mospheric pressure, etc. (1, pp. 163-183). In heavy un¬ drained soils, especially in low places, the water table is very near the surface of the ground. Hence the im¬ portance of drainage. The feeding area of the roots is in the region of the capillary water. If the water table is near the surface the feeding area will be shallow and the plants will be shal¬ low rooted. As the plant removes the water from the feeding area, this water must be restored by capillary action from the area of free water below. It will thus be seen what an important role capillarity plays in plant nutrition. Capillary action varies in different soils both as to rate of water movement and also as to the height to which the water may be raised. Demonstration: Arrange apparatus as in Exercise XII, with the same apparatus and with the same soils (dry). In the experiment have the lower ends of the tubes ex¬ tending about one-half inch below the surface of water held either in a pan, or in a tumbler for each tube. Note the rate at which the water rises in each tube, and also the height of water at the end of four or five days. In the tube of sand the water rises rapidly but soon stops, while in clay it rises slowly but finally reaches the top. The sand is composed of large particles, while the clay is composed of very fine particles. The results of this ex¬ periment would indicate that the power of soils to lift water depends upon the size of their particles; in other words, upon their texture. Application: This exercise shows the disadvantages of sandy soils, for they have very little power to take up moisture from below. As has been suggested, this is because of the large size of soil particles and soil spaces. Such soils may be improved by the addition of fine stable manure or other 22 barnyard refuse, so as to fill up the soil spaces and fur¬ nish finer particles. Temporary improvement may be made by compacting the soil, e. g., by means of a roller. This exercise also shows the value of clay soils or soils made up of fine particles. The property of clay which enables it to raise water through considerable distance makes up, in a measure, for some of the undesirable prop¬ erties which have already been pointed out (Ex. IX). We have seen that water passes through clay soils slowly and that the water of a rain is apt to run off rather than to sink into the ground. The value of drainage should be emphasized in this connection. During the wet weather the free water area is near the surface of the ground, thereby restricting the feeding area of the plants to the first few inches of the soil, and in low places coming so near the surface as to shut off this area entirely. The latter result is well illustrated in nearly ev¬ ery locality where clay soils predominate. In the low places in fields, or such localities, the grain is frequently “drowned out,” or if not “drowned out,” the stalks of grain are slender and unfruitful. On the other hand, during hot, dry weather the water table sinks so low that the capillary connection with the shallow soil area where the roots are distributed is broken. Plants then suffer from insufficient supply of water. The remedy for these two undesirable extremes is drainage. Good drainage means the control of the level of the water table. If during the early wet season the water table is some distance below the surface of the ground, the depth of the feeding area of the roots will be increased. When the dry season comes, the roots will be deep enough to be always supplied with capillary water. Drainage is also important in its influence upon soil ventilation (Ex. XVIII), soil temperature, and the in¬ crease of available plant food. With good drainage and the improvement of texture by means of manures or lime, clay lands are very valuable. (1, pp. 253-260; 2, pp. 75-82; 8.) XIII. Effect of Interrupting the Capillary Current. 23 Explanation: The effect of breaking the capillary connection between the free water below and the feeding area above has al¬ ready been noticed. The effect may be shown by a simple experiment. Demonstration: Fill a glass tube such as used in Exercises XI and XII with dry garden soil to a depth of about two inches; fill the next one and one-half inches of space with dry straw or weeds; fill the remainder of the tube with dry garden soil. Place the tube with its end below the surface of the water as in Exercise XII. Note the rise of water in the tube. When the level of the straw is reached the water stops rising. The large particles of straw break the capil¬ lary connection. Application: Often in farm practice (bad practice) a field is covered after harvest with a heavy growth of grass and weeds. In the spring these are plowed under. Later, if the season is dry, the crop suffers from drouth; the water can not get past the layer of weeds into the feeding area of most of the roots, just as illustrated in the foregoing experi¬ ment. By fall plowing this condition may, in part, be avoided. XIV. Amount of Water Held by Different Soils. Explanation: In Exercise XI a variation may have been noticed in the amount of water necessary to be added to the differ¬ ent tubes before it began to drip from the bottom of the tubes. Some required more water than others. This was due to the difference in capacity of different soils for hold¬ ing water. (1, pp. 157-162.) The amount of water that each kind of soil is capable of holding may be determined as follows: Apparatus: Balances and weights, tubes and rack as in Exercise XI. Demonstration: After tying cloth over the bottoms of four tubes, weigh 24 each tube and keep a record of the weight. The tubes should be numbered so as to avoid confusion. Now fill about half full, tube No. 1 with dry clay, No. 2 with dry humus, No. 3 with dry sand, No. 4 with garden soil. Weigh each one and record the weight opposite the weight of the tube. Add water to each tube until the en¬ tire soil is wet. Cover the tops and allow excess water to drain off. Weigh each tube and record the weight with the entry made of the previous weights of that tube. With these data calculate the per cent, of water held by each kind of soil as follows: Find the actual weight of dry soil by subtracting the weight of the tube (first weight) from the weight of tube plus dry soil; next find the weight of water by subtracting weight of tube plus dry soil from weight of tube plus wet soil. Determine what per cent, the weight of the water is of the weight of dry soil. It will be found that the humus will hold a much larger per cent, of water than any of the other soils, while the sand will hold the smallest per cent. The clay and the garden soil will hold more than the sand. Application: The value of adding organic matter to soils, especially to sandy soils, is here emphasized. It not only helps to increase the capillary power of the sandy soils, and add plant food, but makes them hold water more effectually. We have another point here in favor of clay soils. But this point is sometimes a disadvantage, e. g., in the early spring. Clay soils are cold because they contain so much water. Deep fall plowing and early shallow plowing in the spring may, in part, remove this difficulty. Fall plow¬ ing keeps the water at a lower level and early shallow spring plowing hastens the evaporation of the water. Sandy soils may generally be planted to crops much ear¬ lier in the spring than clay soils. XV. Evaporation of Moisture from Surface of Soils—Dew. Explanation: The notion that dew “falls” still obtains in the minds of many. A simple experiment will show where part of 25 the moisture which we call dew comes from. Part of the moisture of course comes from plants, for they are con¬ stantly giving off moisture (transpiration) but a good deal of it comes from the ground. Demonstration: Invert a tumbler on the surface of moist soil and leave it over night. Drops of moisture (dew) will be seen the next morning clinging to the inside surface of the glass. Application: A great deal of moisture is constantly being evaporated from the soil. At night it is condensed on cold objects in the form of dew. In the care of growing crops, it is im¬ portant to reduce the loss of water through evaporation to a minimum. XVI. How to Keep Moisture in the Soil. Soil Mulch. Explanation: The problem of having a large supply of moisture in the soil and keeping it there, except when used by the plant, is an exceedingly important one. How to keep moisture in the soil may be readily shown. Apparatus: Two one-quart tin cans, balances, and weights. Demonstration: Fill one can nearly full of damp garden soil; fill the other to within one and one-half inches of the top with the same kind of soil and fill the rest of the space with dry garden soil. Weigh each can thus prepared and keep record of the weights. At the end of five or six days weigh again. The difference between the two weights of each can repre¬ sents the loss of water through evaporation. Calculate the percentage of loss of water in each. The loss of water in the second can will be very slight compared with the loss in the first. The layer of dry soil on the second can acts as a blanket, keeping the moisture from evaporating. This covering is known as a mulch. (Fig.l.) Application: In farm practice stirring the soil forms a dry top layer 26 a tumbler of puddled clay (clay that has been wet and stirred until it forms a pasty mass). Keep the contents of both tumblers moist, being especially careful not to allow the clay to get dry enough to crack. In a short time the cutting placed in the sand will take and prevents the loss of water. It also prevents the soil from baking. Stirring the soil is especially important in times of drought. (1, pp. 276-285; 2, pp. 69-71; 9, 21.) XVII. Effect of Crust on Loss of Water. Explanation: The soil may be considered as a sponge holding water for the plant’s use. The effect of a top crust on the loss of water from the lower layers of soil may be illustrated as follows: Demonstration: Fill a sponge with water and support a dry brick above it so that part of the weight of the brick presses against the sponge. The brick removes the water from the sponge and in a short time the sponge will have little water left. Application: This is another illustration of the importance of stir¬ ring the top layer of the soil. It explains why the suc¬ cessful farmer begins his cultivation as soon after a rain as possible. XVIII. Air in Soils a Necessity for Plant Growth. Explanation: Plants as well as animals must have oxygen. Part of the oxygeh supply of the plant must come by the way of the roots; besides, the roots themselves need oxygen. A simple experiment will illustrate the necessity of roots being supplied with oxygen. Material: Cuttings of Wandering Jew (tradescantia or some other plant that roots easily from cuttings), two tumblers. Demonstration: Put one cutting in a tumbler of wet sand and another in 27 root and in a few weeks it will show a decided growth. The cutting placed in the clay will probably die in a few weeks. The chief difference in the two instances is in the amount of oxygen. The same thing may be shown in another way. Put one cutting in fresh well water and another in water that has been boiled for some time and then cooled. Boiling the water drives off the oxygen. After a few weeks the same difference will be shown as between the cuttings noted above. Application: We have here an explanation of why in low, poorly drained places plants are “drowned out.” “Smothered out” would more nearly express the truth. Plowing and draining the soil and, to a certain extent, cultivation help to give the roots oxygen. When the texture of clay is im¬ proved by making the soil spaces larger, not only is a larger feeding area secured (an area containing capillary water), but also a breathing area (soil spaces filled with air for the roots). (1, pp. 239-252; 2, p. 66; 8; 9; 25.) XIX. Amount of Air Held by the Soil. Explanation: We have seen that plants require water in the form of capillary water and that they also require air (oxygen). The question of how much water and air the soil should contain may be answered approximately by an experi¬ ment. Demonstration: Fill five tumblers with garden soil and plant in each five wheat grains. Add water daily as follows: to No. 1, 15cc.; to No. 2, 10 cc.; to No. 3, 5 cc.; to No. 4, 3 cc.; to No. 5, 1 cc. After a few weeks note the difference in size and vigor of the plants. Select the tumbler which con¬ tains the plant showing the best growth. In this the right amount of water has been added. Insert a small tube at the side of the tumbler so that it will extend to the bottom. Pour water into this tube by means of a funnel (keeping account of the amount of 2S water added) until the water stands level with the sur¬ face of the soil. The water added to the soil displaces the air, therefore this volume of water is equal to the volume of air in the soil spaces. Compare this with the total volume of soil (the volume of soil may be found by removing the soil from the tum¬ bler and filling to the level of the surface of the soil with water. The volume of water added in cubic centimeters represents the volume of the soil). Find what per cent, the volume of air is of the volume of the soil. In general, a soil should contain water equal to about 60 per cent, of its water-holding capacity. This leaves 40 per cent, (two- fifths) of the soil spaces to be occupied by air. See how these figures compare with amount calculated in above experiment. XX. Fertility of the Soil. Plant Food. Explanation: Thus far little has been said about plant food. The plant must have certain substances that are dissolved in the water of the soil. These substances that are taken into the plant from the soil are known as available plant food. (2, pp. 31-37; 4; 5; 6; 7.) Demonstration: Fill two cans or flower pots with clean sand (sand that has been washed as directed in Ex. IX). Plant the same number (six) of grains of wheat in each. Keep one wet or moist with rain water. Keep the other in the same con¬ dition as to moisture with rain water to which has been added plant food at the rate of two compressed tablets to each pint of water. * *Note—Each tablet is composed of : Common table salt (sodium chloride) 2 % grains (.162 grams); plaster of Paris—gypsum (calcium sulphate), 2% grains (.162 grams); Epsom salts (magnesium sulphate, 2 % grains, (.162grams); phosphate of lime, nearly the same as burned bones (calcium phosphate), 2% grains (.162 grams; East India saltpetre- nitre (potassium nitrate), 5 grains (.325 grams); compound of iron and chlorine (ferric chloride), nearly 1-10 grains. 2 9 For awhile there will be no difference in the growth of the plants in the two cans. In the course of two or three weeks, when the food stored up in the grains is exhausted, the plants in the first can will cease to grow or grow very little, while those in the second can will continue to grow vigorously. The substances added to the rain water used in the second can are necessary to the plant’s growth. Such substances when applied to soils are known as fer¬ tilizers. XXI. Commercial Fertilizers. Explanation: The tablets used in previous exercise contain nearly all the substances that the plant derives from the soil. All but three of these (nitrogen, phosphorus, and potas¬ sium) are generally found in the soil in sufficient quanti¬ ties for the need's of the plant. The “essential ingredi¬ ents” of a fertilizer are substances containing these ele¬ ments ; i. e. substances which supply (a) nitrogen as ni¬ trate of soda, dried blood, hoof meal, etc., (b) phosphorus in form of phosphoric acid as bone meal (raw or steamed), mineral phosphates, etc., (c) potassium in form of potash as wood ashes, kainite, muriate or sulfate of potash, etc. A complete fertilizer is one that contains nitrogen, phosphoric acid, and potash in proportions supposed to be suited to the needs of certain crops. Such a fertilizer is made by mixing substances containing the basic ingre¬ dients so as to give the desired proportion of nitrogen, phosphoric acid, and potash. It is often the practice to use substances rich in these “essential ingredients” and dilute the mass to the desired strength by means of some inert material such as dry earth. Materials used in this way in this way are called fillers. A 2-8-4 fertilizer means one that contains 2 per cent, nitrogen, 8 per cent, phos¬ phoric acid, and 4 per cent, potash. If the percentages of available basic ingredients are known it is an easy mat¬ ter to calculate the value of a fertilizer. Nitrate of soda contains 15.8 per cent, nitrogen; ni¬ trate of potash, 13 per cent, nitrogen and 45 per cent, pot- 30 ash; sulfate of ammonia, 20.5 per cent, nitrogen; muri¬ ate of potash, 50 per cent, potash; acid phosphate, from 14 to 16 per cent, phosphoric acid. Problems: 1. How many pounds of nitrogen are in a ton of nitrate of soda? What is the value of a ton of nitrate of soda if nitrogen is worth 14 cents a pound? 2. Suppose an equivalent of 200 pounds per acre of a 5-8-2 fertilizer is to be applied to 20 acres, determine: (a) How much of each of the following fertilizer in¬ gredients would be required: 1. Nitrate of soda, 96 per cent, pure, at $50 a ton. 2. Acid phosphate containing 14 per cent, available phosphoric acid, at $15 a ton. 3. Potassium chloride (muriate of potash), 80 per cent, pure, at $40 a ton. (b) What would be the cost per ton of a 5-8-2 fer¬ tilizer based upon cost of ingredients as calculated in (a)? (c) How much less would the mixture weigh made from above separate fertilizers than if a 5-8-2 fertilizer were purchased? In other words, how many pounds of filler must be added per ton in order that the 5-8-2 proportion be maintained? * Application: These problems illustrate a practical application of arithmetic in estimating the value of a commercial fer¬ tilizer. One should remember that the lowest stated amount of available nitrogen, phosphoric acid, and pot¬ ash are the only materials to be considered in a guaran¬ teed analysis although other statements frequently occur in the printed analysis of a fertilizer. State Experiment Stations furnish bulletins giving analysis of various commercial fertilizers on the market. By means of these bulletins, and by knowing the market * From Circular 77, Office of Experiment Stations, U. S. Department of Ag¬ riculture. 31 price of the “essential ingredients” the actual value of any fertilizer may be readily estimated. (2, pp. 185-253.) XXII. How to Know What Kind of Plant Food the Soil Needs. Explanation: This is a hard question to answer definitely. Many times certain fertilizers are added to soils but produce no results. They do not fulfill the needs of the crop. It is important, if possible, to know the needs of the soil with respect to the intended crop before it is planted. To make such a test as this is a problem that has been much studied. A rough or approximate test has been suggested by the U. S. Bureau of Soils. Directions for making this test will be found in 26. Directions for making the test in a different way may be found in 10. Boys of the seventh or eighth grade should be able to carry out the instructions of these references. . The chemicals needed may be obtained at a drug store or where fertilizers are for sale. The practical value of such tests is fully described in 23 and 24. Reference Books and Pamphlets. These references should be in the school library for use in connection with the work outlined in this bulletin. The prices of books are given so that they may be obtained direct¬ ly from the publishers. The pamphlets are all free and may be obtained by pos¬ tal cards to the addresses indicated below * and giving the number of the publications wanted. In the case of U. S. Gov¬ ernment publications give also the class to which they be¬ long (Farmers’ Bulletin No. 77; Office of Exp. Sta., Cir. No. 52, etc.) 1. The Soil. By F. H. King. New York: Macmillan Co., pp. 303.$1.50 2. First Principles of Soil Fertility. By Alfred Vivian. New York: Orange Judd Co., pp. 265.90 32 3. The First Book of Farming. By C. L. Goodrich. New York: Doubleday, Page & Co., pp. 250.. 1.00 4. The Value of Barnyard Manure. Bulletin No. 134. 5. The Maintenance of Fertility. Bulletin No. 141. 6. Ohio Soil Studies. Bulletin No. 150. 7. Maintenance of Fertility. Bulletins Nos. 159, 167, 168. 8. Soil and Drainage. Vol. 1, No. 2. 9. An Elementary Story of the Soil. Vol. 1, No. 4. 10. Testing Soils. Vol. 1, No. 6. 11. Conditions Necessary for Plants to Grow Well. Vol. 1, No. 8. 12. Tillage and Cultivation. Vol. 1, No. 9. 13. The Formation of the Soil. Vol. 2, No. 5. 14. Drainage. Vol. 3, No. 1. 15. Preparation of the Seed Bed. Vol. 4, No. 1. 16. The Roots of Plants. Bulletin No. 127. 17. A Few Good Books and Bulletins on Nature Study, School Gardening, and Elementary Agriculture for Common Schools. Office of Experiment Stations. Cir. No. 52. 18. Education for Country Eife. Office of Experiment Sta¬ tions, Cir. No. 84. 19. The Use of Illustrative Material in Teaching Agriculture in Rural Schools. 1905 Year Book Reprint, No. 382. 20. Exercises in Elementary Agriculture. Office of Experi¬ ment Stations, Bulletin No. 186. 21. Simple Exercises Illustrating Some Applications of Chemistry to Agriculture. Office of Experiment Stations, Bulletin No. 195. 22. The Liming of Soils. Farmers’ Bulletin, No. 77. 23. Renovation of Worn-out Soils. Farmers’ Bulletin, No. 245. 24. Soil Fertility. Farmers’ Bulletin, No. 257. 25. Management of Soils to Conserve Moisture. Farmers’ Bulletin, No. 266. 26. The Wire-basket Method for Determining the Manurial Requirements of Soils. Bureau of Soils, Cir. No. 18. ♦Note—Nos, 4, 5, 6, 7; Ohio Agricultural Experiment Station, Wooster, Ohio. Nos. 8, 9, 10, 11, 12, 13, 14,15; Extension Department, Agricultural College, Ohio State University, Columbus, Ohio. No. 16; Kansas Agricultural Experiment Station, Manhattan, Kan. Nos. 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, U. S. Department of Agriculture, Washington, D. C. (Address Sec’y of Agriculture.) 33 List of Apparatus Required for Work Outlined. 1. Balances, Harvard Trip Scales .$4.15 2. Weights (iron, 1 kilo, to 5 grams) . 1.05 3. Funnel, small, glass .10 4. Graduate, 50 ccm.55 5. Glass tubing, assorted sizes, y 2 lb.25 6. Rubber tubing, in. 3 ft..30 7. Wide-mouthed bottles, with corks, 6 oz., ]/ 2 doz... .20 8. Sponge .10 9. Candle .03 10. Tumblers, common glass, y 2 doz.15 11. Student-lamp chimneys .50 12. Oil cloth, 4 yds.80 13. Lumber for boxes (for Ex. VI.) . 1.00 14. Compressed plant-food tablets.10 15. Slacked lime, small quantity . 16. Tin cans (tomato or fruit cans with tops melted off) 17. Rack for tubes, Ex. XI. (to be made by pupils. ... 18. Dry goods boxes to make case for protecting plants 1.00 Total .$10.28 Substituting spring balances, costing 25 cents, for 1 and 2, deduct . 4.95 $5.33 Note—Nos. 1, 2, 3. 4, 5, may be obtained from the Columbia School Supply Co, In¬ dianapolis, Ind., or from any firm dealing in laboratory supplies; Nos. 6, 7 and 8, at any drug store; Nos. 9, 10, 11 and 12, at any general merchandise store; Nos, 13 and 18, might be donated to the school; No. 14, enclose 10 cents for box of “compressed plant food tab¬ lets,” and address Edward F. Bigelow, Sound Beach, Conn. The items of greatest expense are 1 and 2, but they are so important in a school equipment that they should be obtained if possible. 34 Provision for Keeping Plants Alive During Cold Weather. Where the temperature of the building falls below freez¬ ing at night or during the interval between Friday and Monday, some provision must be made for keeping plants alive. The few plants that are needed in connection with some of the foregoing exercises may be protected from cold by use of a double-walled case. The walls, including the bottom, should be from six to eight inches apart, and the spaces filled tightly with packing material (straw, saw-dust, or excelsior). Such a case may be made by using a large dry goods box about four feet square for the outer walls, and a smaller box about two and one-half or three feet square for the inner walls. In putting them together and in filling the spaces with packing material the edges of the open ends of the boxes should be parallel (on a line). The spaces should be packed even with the open ends of the boxes and then covered with boards. This completes an open case with walls and bottom six or more inches thick. A double door or lid must be made to close the opening. It may be made by constructing a frame six or seven inches wide that will just fit the opening. One side of the frame is then covered with thin boards. The box thus formed is to be filled with packing, and enclosed by nailing boards over the open side. It is convenient to have these boards extend about two inches around the margin of the box. In order to make the lid fit tightly, its edges should be covered with thick cloth. This is very important, for a very small crack will allow the cold to enter. A couple of leather handles attached to the outside completes the lid. If the box is properly constructed with a thick, tightly fitting lid, plants may be kept alive for several days, even in very cold weather. The plants must be put in and the box closed while the air in the room is warm (the warmer the better). The thick walls of the box will then retain a suffi¬ cient amount of this heat to keep the temperature above freez¬ ing. During the day-time while the school-room is warm the plants must be taken out and kept in sunlight. v By placing the box with the opening at the side, the top map" be used as a laboratory table. PUBLICATIONS OF OHIO STATE NORMAL COL¬ LEGE OF MIAMI UNIVERSITY. These publications form a series of teachers’ bulletins is¬ sued by the Ohio State Normal College of Miami University for the benefit of the teachers of the State, and in the inter¬ est of public education. All requests from teachers desiring these bulletins, or in¬ formation regarding educational movements, will receive prompt attention. Address Teachers’ Aid Bureau, Ohio State Normal College, Oxford, Ohio. 1. Nature-Study, by George W. Hoke, 12 pp., 3 figs., Octo¬ ber, 1903. Outline for study of trees, weeds, insects, birds, etc., with list of books for reference. 2. Geography, by George W. Hoke, 15 pp., 1 plate, May, 1904. Treats of principles of Geography, and Regional Geography, with suggestive exercises for class work. 3. Evolution of Public Education in Ohio, (A) Legislation, by Harvey C. Minnich, 20 pp., 2 maps, March, 1907. A historical account of school legislation. 4. The Manual Arts, by F. C. Whitcomb, 15 pp., April, 1907. Suggestions as to course of study and equipment, with special reference to needs of small school systems. 5. The Soil and Its Relation to Plants, by B. M. Davis, 35 pp., 6 figs., May, 1907. Subject presented by means of simple experiments. 6. Evolution of Public Education in Ohio, (B) Certifica¬ tion, by Harvey C. Minnich, 23 pp., November, 1907. Continuation of No. 3. 7. Experimental Studies of Plant Growth, by B. M. Davis, 31 pp., 17 figs., May, 1908. Forty-two experiments suit¬ able for small high schools. 8. Stories for the Elementary Grades, by Anna E. Logan, 20 pp., September, 1908. Arranged with special refer¬ ence to the needs of teachers, introducing, or increasing story-telling work in their schools. 9. Arithmetic in the Grades, by T. L. Feeney, 19 pp., Janu¬ ary, 1909. General discussion followed by outline of course of study. 10. English in the Grades, by Frances Gibson Richard. 2>j pp., March, 1909. Detailed outline including titles A selections for all the grades. , ; 11. The Soil and Its Relation to Plants, by B. M. Davisy 3> pp., December, 1909. Revised edition of No. 5. 36