Text-book of botany, morphological and physiological . n plane of the organ. As long as theorgan grows most rapidly on the dorsal side, it may be termed, after de Vries,hyponastic, afterwards, when it grows most rapidly on the inner or upper side,epiuasiic. Since in the later stages of development of an organ growth ceases atcertain places—while at different distances from these places it presents differentstages of growth, until it finally ceases everywhere—it is clear that in the same organ,by the side of spots where growth is completed and nutation no longer takes place,others occur with hy
Text-book of botany, morphological and physiological . n plane of the organ. As long as theorgan grows most rapidly on the dorsal side, it may be termed, after de Vries,hyponastic, afterwards, when it grows most rapidly on the inner or upper side,epiuasiic. Since in the later stages of development of an organ growth ceases atcertain places—while at different distances from these places it presents differentstages of growth, until it finally ceases everywhere—it is clear that in the same organ,by the side of spots where growth is completed and nutation no longer takes place,others occur with hyponastic and others again with epinastic growth, until at lengthnutation and growth alike cease altogether, as in Fern-leaves. Seedlings of Dicotyledons are a remarkable illustration of bilateral structureswhich nutate in one plane; although their stem and primary root become afterwardsmultilateral and grow vertically upwards and downwards. The stem terminates ina pendent or nodding bud ; and the curvature, which is generally very great, exhibits. FIG. 454.—Nutation of the filaments of Dzctanntus Fraxniella; the filaments of the stamens whose anthers have notyet opened are bent downwards ; those with anthers already burst are bent upwards. itself also in germination when it takes place out of the ground, in a vessel thatrotates slowly round a horizontal axis; it is a true curvature of nutation inde-pendent of light and gravitation. But the older portions of the stem become straightas they develope from the curved portion; and in proportion as the stem increasesin length, the straight part which bears the nodding bud also lengthens. Whengermination takes place in a feeble light, or better in a slowly rotating vessel, amore rapid growth occurs of the older portion of the stem which was at first con-cave, causing it to become convex on this side; and hence the older and youngerparts of the stem form together a letter S, as in Phaseolus, Vicia Fada, PolygoniijjiFagopyriwi, Cr
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectbotany, bookyear1875
