. The essentials of botany. Botany. 130 PLANT PHYSIOLOGY laboratory study (b) after paragraph 146). Keep in the dark until the stem and roots are both in a vertical position. Place in a box, closed on all sides, except for an opening about 10 mm. wide at one side, and direct this opening toward a win- dow. Note the direction of curvature of stem and roots, as well as the region where the curvature occurs. (/) Perform experiments similar to the foregoing, placing orange-red glass or deep blue glass in front of the opening, and note the results. (g) Sterilize some fresh horse manure in a steam s
. The essentials of botany. Botany. 130 PLANT PHYSIOLOGY laboratory study (b) after paragraph 146). Keep in the dark until the stem and roots are both in a vertical position. Place in a box, closed on all sides, except for an opening about 10 mm. wide at one side, and direct this opening toward a win- dow. Note the direction of curvature of stem and roots, as well as the region where the curvature occurs. (/) Perform experiments similar to the foregoing, placing orange-red glass or deep blue glass in front of the opening, and note the results. (g) Sterilize some fresh horse manure in a steam sterilizer to destroy all the fungi, and inoculate with the manure mold, Pilobolus. When the sporangia of this are about to be formed, place the dish containing the culture, uncovered, in a dark box, tilting the dish at an angle of 45 degrees toward one side, where a small window about cm. in diameter is left open to admit light, but covered on the inside with a glass plate. Place the box in such a position that the light can enter the window. The sporangia will direct themselves toward the light and discharge their spore masses, which wiU stick to the glass covering the window. Only a few shots wiU fail to hit the "bull's eye" if the distance from the dish of the fungus to the window is not more than 10 to 20 cm., although these are discharged with considerable accuracy much further than that. Try the effect of different colored glass on the accuracy of the aim. (h) Germinate a number of seeds of broom-corn millet or proso (Panicum imiliaceum) in the dark, in a pot of earth. When they have attained a length of 1 to 2 cm., cap the tips of half of the seed- lings with little caps of tinfoil, made over ^ the point of a pencil, and then gently Fig. . clipped over the tip of the seedling and experiment (/i). pinched in place. Set the pot in the box used for experiment (e), and note the result. Almost as good results can be obtained by using oats. (i) Ge
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