. Elementary botany . Fig. 30. Root hairs of corn seedling with soil particles adhering closely. Iit \\i root na^rs> we find tnat small particles cling so tenaciously to 'i' I J J'J the root hairs that they are not removed. Placing a few such root hairs under the microscope it appears as if here and there the root hairs were glued to the minute soil particles. 54. If now we take some of the soil which is only moist, weigh it, and then permit it to become quite dry on exposure to dry air, and weigh again, we will find that it loses weight in drying. Moisture has been given off. This moisture
. Elementary botany . Fig. 30. Root hairs of corn seedling with soil particles adhering closely. Iit \\i root na^rs> we find tnat small particles cling so tenaciously to 'i' I J J'J the root hairs that they are not removed. Placing a few such root hairs under the microscope it appears as if here and there the root hairs were glued to the minute soil particles. 54. If now we take some of the soil which is only moist, weigh it, and then permit it to become quite dry on exposure to dry air, and weigh again, we will find that it loses weight in drying. Moisture has been given off. This moisture, it has been found, forms an exceedingly thin film on the sur- face of the minute soil particles. Where these soil particles lie closely to- gether, as they usually do when massed together in the pot or elsewhere, this thin film of moisture is continuous from the surface of one particle to that of an- other. Thus the soil particles which are so closely attached to the root hairs connect the surface of the root hairs with this film of moisture. As the cell- sap of the root hairs draws on the moisture film with which they are in con- tact, the tension of this film is sufficient to draw moisture from distant parti- cles. ]n this way the roots are supplied with water in soil which is only moist. 55. Plants cannot remove all the moisture from the soil. — If we now take a potted plant, or a pot containing a number of seedlings, place it in a moder- ately dry room, and do not add water to the soil it will be found in a few days that the plant is wilting. The soil if examined will appear quite dry to the sense of touch. Let us weigh some of this soil, then dry it by artificial
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