Laboratory and field manual of botany . f the beans upside down and pin them in the reversed position. Ifyou choose, after a few days reverse them again. Make sketches of the vari-ous forms that the roots assume and discuss these. References. Detmer-Moor, 9; Pfeffer-Ewart, 81, HI. EXPERIMENT XVIII Does the Windsor bean root tip press downward with a force greater than itsown weight? Arrange a sprouted bean as shown in Fig. 2,i selecting onethat has a root about twiceas long as the diameter ofthe bean and that hasgrown out horizontally,having been sprouted on asheet of wet blotting be
Laboratory and field manual of botany . f the beans upside down and pin them in the reversed position. Ifyou choose, after a few days reverse them again. Make sketches of the vari-ous forms that the roots assume and discuss these. References. Detmer-Moor, 9; Pfeffer-Ewart, 81, HI. EXPERIMENT XVIII Does the Windsor bean root tip press downward with a force greater than itsown weight? Arrange a sprouted bean as shown in Fig. 2,i selecting onethat has a root about twiceas long as the diameter ofthe bean and that hasgrown out horizontally,having been sprouted on asheet of wet blotting bean is pinned to acork that is fastened withbeeswax and rosin mixtureto the side of a little troughor pan of glass or glazedearthenware. The pan isfilled half an inch or morewith perfectly clean mer-cury, and on top of the mercury is a layer of water. The whole is closelycovered by a large tumbler or a bell glass. Allow the apparatus to standuntil the root has forced its way down into the mercury. Then run a slender 1 Or see Ganong, Fig. 2. A sprouting Windsor bean pushing itsroot tip into mercuiy s, seed; r, root; w, layer of water; m, mercuryAfter Sachs 36 STRUCTURE AND PHYSIOLOGY OF SEED PLANTS needle into tlie root at the level of the mercury (to mark the exact level),withdraw the root, and measure the length of tlie part submerged in see whether this part would have stayed under by virtue of its own weight,cut it off and lay it on the mercury. Push it under with a pair of steel for-ceps and then let go of it. What does it do ? EXPERIMENT XIX What causes the root to go downward ? A. Pin some soaked Windsor beans to a large flat cork, cover them withthoroughly moistened chopped peat moss, and cover this with a thinglass crystallizing dish. Set the cork on edge. B. Prepare another cork in the same way, attach it to a clinostat, andkeep it slowly revolving in a vertical position for from three to fivedays. Compare the directions taken by the roots on the station
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