. Plant physiology. Plant physiology. MOVEMENTS OF VARIATION 281 four pinnate leaflets are palmately attached; each of these leaflets consists, in turn, of a secondary petiole and rachis, which bears a large number of small leaflets of the third order (Fig. 158). The main petiole bears at its base a weU- developed cushion or pulvinus, and organs of this kind occur also at the bases of the petioles of the leaflets of the second and third orders. A very slight touch upon the largest pulvinus is enough to cause the primary petiole to fall, and the leaflets of the third order to become erect with
. Plant physiology. Plant physiology. MOVEMENTS OF VARIATION 281 four pinnate leaflets are palmately attached; each of these leaflets consists, in turn, of a secondary petiole and rachis, which bears a large number of small leaflets of the third order (Fig. 158). The main petiole bears at its base a weU- developed cushion or pulvinus, and organs of this kind occur also at the bases of the petioles of the leaflets of the second and third orders. A very slight touch upon the largest pulvinus is enough to cause the primary petiole to fall, and the leaflets of the third order to become erect with the upper surfaces of each pair of. Pig. 158.—^Leaves of Mimosa -pudica. A, normal position; B, Pfeffer.) after stimulation. {After opposite leaflets against each other (Fig. 158, B). If the stimulus is strong enough it is propagated through the stem to the other leaves of the plant, both above and below, and these also fall and fold together. After a time the leaves gradually re-expand and regain their earlier positions. These phenomena occur in completely mature leaves, and they are entirely independent of growth. Observations relating to details of the response here considered have shown that the movements of the leaf are caused by changes in the form of the 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 Palladin, Vladimir Ivanovich, 1859-1922; Livingston, Burton Edward, 1875-; Hopping, Aleita, 1890-. Philadelphia, P. Blakiston's Son & Co
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Keywords: ., book, bookcentury1900, bookdecade1910, booksubjectplantphysiology
