. Lessons in botany. Botany. 104 BOTANY. Exercise 37. 179. Growth of the stem.—We may use a bean seedling growing in the soil. At the junction of the leaves with the stem there are enlargements. These are the nodes, and the spaces on the stem between successive nodes are the internodes. We should mark off several of these internodes, espe- cially the younger ones, into sections about $mm long. Now observe these at several times for two or three days, or more. The region of elongation is greater than in the case of the roots, and extends back further from the end of the stem. In some young gard
. Lessons in botany. Botany. 104 BOTANY. Exercise 37. 179. Growth of the stem.—We may use a bean seedling growing in the soil. At the junction of the leaves with the stem there are enlargements. These are the nodes, and the spaces on the stem between successive nodes are the internodes. We should mark off several of these internodes, espe- cially the younger ones, into sections about $mm long. Now observe these at several times for two or three days, or more. The region of elongation is greater than in the case of the roots, and extends back further from the end of the stem. In some young garden bean plants the region of elonga- tion extended over an area of \omm in one internode. 180. Force exerted by growth.—One of the marvellous things connected with the growth of plants is the force which is exerted by various members of the plant under certain condi- tions. Observations on seedlings as they are pushing their way through the soil to the air often show us that considerable force is required to lift the hard soil and turn it to one side. A very striking illustration may be had in the case of mushrooms which sometimes make their waythrough the hard and packed soil of walks or roads. That succulent and tender plants should be capable of lifting such comparatively heavy weights seems incredible until we have witnessed it. Very striking illustrations of the force of roots are seen in the case of trees which grow in rocky situations, where rocks of considerable weight are lifted, or Lever auxanometer (Oels) for measuring elongation of email n'-ffc in lai-o-^ vc^rArc the stem during growth. Mlld,n Hits 111 large TOCKS are widened by the lateral pressure exerted by the growth of a root, which entered when it was small and wedged its way Fig. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.
Size: 1544px × 1619px
Photo credit: © Central Historic Books / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublisher, booksubjectbotany
