On many lawns it may be noticed that the grass is not thriving. It has a sickly appearance, and even the application of fertilizer does not seem to remedy the conditions. Perhaps the ground has become so hard that the air cannot penetrate and the grass is being smothered. If the surface of the soil can be loosened with a garden rake, and clover seed sown, much good may be accomplished. The clover is a tap-rooted plant, sending its main root deep into the soil. After the death of the plant, the root decays, and the nitrogen which is stored in it can be used as food by the other plants. Most useful of all, however, in such cases, the decay of the tap-root of the clover makes a passage deep into the soil and thus allows the air to enter. Consult Figs. 39-41. LEAFLET X. THE BROOK.[12] BY J. O. MARTIN. INTRODUCTION BY L. H. BAILEY. [12] Nature-Study Quarterly, No. 5: Leaflet 18. June, 1900. [Illustration] A brook is the best of subjects for nature-study. It is near and dear to every child. It is a world in itself. It is an epitome of the nature in which we live. In miniature, it illustrates the forces which have shaped much of the earth's surface. Day by day and century by century, it carries its burden of earth-waste which it lays down in the quiet places. Always beginning and never ceasing, it does its work as slowly and as quietly as the drifting of the years. It is a scene of life and activity. It reflects the sky. It is kissed by the sun. It is caressed by the winds. The minnows play in the pools. The soft weeds grow in the shallows. The grass and the dandelions lie on its sunny banks. The moss and fern are sheltered in the nooks. It comes one knows not whence; it flows one knows not whither. It awakens the desire of exploration. It is a realm of mysteries. It typifies the flood of life. It goes "on forever." In many ways can the brook be made an adjunct of the school-room. One teacher or one grade may study its physiography; another its birds; another may plat it. Or one teacher and one grade may devote a month or a term to one phase of it. Thus the brook may be made the center of a life-theme. L. H. B. I. A BROOK AND ITS WORK. On a rainy day most of us are driven indoors and thus we miss some of nature's most instructive lessons, for in sunshine or rain the great mother toils on, doing some of her hardest labor when her face is overcast with clouds. Let us find our waterproofs, raise our umbrellas, bid defiance to the pattering rain, and go forth to learn some of the lessons of a rainy day. [Illustration: _Fig. 42. The brook may be made the center of a life-theme._]