. Plant studies; an elementary botany. Botany. ROOTS 93 tliroiigh the holes, so that the seeds rest on the paper, and the root tips hang througli tlie holes. If tlie pajier is kept moist germination will eontinne, but geotropisni will pull the root tips downwards, and liydrotropism (tlie moist paper) will pull tliem upwards. In this way tliev will pursue a devidus eourse, now directed Ijy one influence and now by the other. If a root .system be examined it will lie found that when there is a main [taj) runt) it is d i r e c t e d steadily downwards, while the branches are directed d i If
. Plant studies; an elementary botany. Botany. ROOTS 93 tliroiigh the holes, so that the seeds rest on the paper, and the root tips hang througli tlie holes. If tlie pajier is kept moist germination will eontinne, but geotropisni will pull the root tips downwards, and liydrotropism (tlie moist paper) will pull tliem upwards. In this way tliev will pursue a devidus eourse, now directed Ijy one influence and now by the other. If a root .system be examined it will lie found that when there is a main [taj) runt) it is d i r e c t e d steadily downwards, while the branches are directed d i If e r e n 11 y. This indicates that all jiarts of a root system are not alike in their resi)(inse to these influ- ences. Several other influences are also con- cerned in directing soil roots, and the path of any roiit brancli is a result of all of them. How variable they are may be seen liy the numerous directions in which the liranches travel, and the whole root system preserves the record of these numerous paths. (2) TJie ^.)»// on the stem.—Another root property may be noted in connection with the soil root, namely tlie pull on the stem. When a strawberry runner strikes root at tip (see Fig. 47), the roots, after they obtain anchorage in the soil, pull the tip a little beneath the surface, as if thev had gripped the soil and then slightly contracted. The same thing may be observed in the process known as. Fn;. gs. A section through the etem of a water- w ort {Elatiiit), showing the renmrkabiy large ;ind regnlariy arranged air passages for root aeration. The single reduced vascnlar bundle is central and connected «ith the small cor- tex by thin plates of cells whicli radiate like tlie spokes of a wheel.—After 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 Coulter, John Merle, 1851-1928. New
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectbotany, bookyear1900
