. Lessons in botany. Botany. HOW PLANTS OBTAIN THEIR LIQUID FOOD. 41 weight ? Can plants remove all the moisture from the soil by absorption through their roots ? Demonstration 15a (or Exercise). 78a. To demonstrate the action of a root hair.—Take a long potato, cutoff the ends squarely, and bore a smooth hole from one end nearly through to the other end, being careful not to split the potato. Now pare off the sides to make a tube closed at one end. Rest the closed end in a vessel of water, as shown in fig. 25a, after having filled the tube with sugar. After five or six hours examine. The suga
. Lessons in botany. Botany. HOW PLANTS OBTAIN THEIR LIQUID FOOD. 41 weight ? Can plants remove all the moisture from the soil by absorption through their roots ? Demonstration 15a (or Exercise). 78a. To demonstrate the action of a root hair.—Take a long potato, cutoff the ends squarely, and bore a smooth hole from one end nearly through to the other end, being careful not to split the potato. Now pare off the sides to make a tube closed at one end. Rest the closed end in a vessel of water, as shown in fig. 25a, after having filled the tube with sugar. After five or six hours examine. The sugar inside of the potato tube draws water inward from the vessel, imitating the action of a root hair. Exercise 1 8. 79. Salt particles cling to root ^ Potato J^'^al cavity con- Have at hand small pots of seedlings the taining sugar, standing in vessel of ., r .... t, it i- water. B, section of potato tube SOll of which IS not wet. Full, Or dig, up a showing cavity only partly filled with seedling. Observe the soil clinging to the suSar- <After MacDougal.) roots. Agitate it to remove as much of the soil as possible. Wash the roots by rinsing in water. Are all the soil particles removed ? To what portions of the roots does most of the soil cling ? Why ? Compare with seedlings grown in a germinator free from III. Strong Solutions of Plant Food are Injurious. Exercise 19 (or Demonstration). 80. To show the eftect on plants of food solutions which are too strong.— Potassium nitrate is one of the food substances used in the water cultures. It is also one of the necessary food substances from which nitrogen is obtained for the plant. Take strongly concentrated solutions, say a 5$, a io#, and a 20$ solution. Label three pots of seedlings to correspond with the solutions. Pour in enough of each solution to the corresponding pots to saturate the soil. In the course of three or four hours (or later) observe the result. Observe the condition of the stems at the surface
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