Starch in plants, 64, 66.
    iodine test for, 64.

  Stems, 8, 120.
    distinguished from roots, 120.
    habit of growth of, 121.
    structure of, 125.
    underground, 121.
    uses of, 120.
    work of checked, 126.

  Stigma, 130.

  Stomata, 110.

  Stones, 26, 31.

  Stony loam, 29.

  Strawberry flowers, 134.
    perfect, 135.
    pistillate, 135.

  Study of plants begun, 6.

  Style, 130.

  Sugar cane, 5.
    soil, 162.

  Sugar in plants, 64, 66.

  Sulphate of ammonia, 194.

  Sulphate of potash, 199.

  Sulphur in plants, 66.

  Sun, work of in making soils, 32, 34.

  Sunlight, and the farmer, 5.
    necessary for leaf work, 110, 111, 112.

  Superphosphates, 198.

  Swamp muck, 30.

  Sweet clover, 190.

  Sweet potato roots, 13.
    soils, 28, 160.

  Sweet potatoes, 5.

  Sylvinite, 199.

  Systems of cropping, 119.

  Tankage, 194.
    as fertilizer, 194.
    nitrogen in, 194.
    phosphoric acid in, 194.

  Temperature of soil, 57.

  Tendrils, plants climb by, 122.

  Testing seeds, 75.

  Testing soils for water, 162.
    for plant food, 215.

  Texture of soils, 37, 143, 150.

  Thinning fruit, 137.

  Thistle, 6.

  Thistle family, 86.

  Thomas slag, 198.
    as fertilizer, 198.
    phosphoric acid in, 198.

  Tillage and plant food, 67.
    and fertility, 150.

  Time to begin this study, 3.

  Time to plow, 98.

  Tobacco soils, 27.

  Tomato soils, 161.

  Tools, 5.
    and the farmer, 5.

  Transpiration, the fact, 110.
    amount of, 111.

  Transplanting, 87.
    machines, 89.

  Truck of plow, 95.

  Truck soils, 27, 28, 29, 161.

  Tubercles on roots of legumes, 68, 144.

  Turnip, 6.

  Type soils, 26.

  Under drains, 237.
    advantage of, 237.

  Underground stems, 121.

  Value of knowledge of flowers, 134.

  Vegetables,
    roots, 13, 14, 15.
    soil for, 28.

  Ventilation of soils, 68, 142.
    necessary for germination, 73.
    necessary for root growth, 21, 22, 23.
    necessary for fixation of nitrogen, 144.

  Water, absorption of by soil, 40, 43, 46, 142.
    amount used by plants, 40.
    capillary, 49, 153.
    evaporation of, 54, 155.
    free, 48, 153.
    film, 50.
    ground, 48.
    importance of to plants, 39.
    percolation of, 41.
    relation of soils to, 39.
    standing, 48.
    work of in making soils, 33, 35.