(5

Common Bean.—

Nutation of Plumules

(1) Jan 2d 77 Seedling A Common Bean lying on one side on wet sand & with radicle deeply buried in sand— when plumule appeared as a small knob, ie the summit of arc, but the upper & lower part cd not be seen projecting above general level of bean rather above .1 of inch, & almost in same Horizontal plane with the bean itself I attached fine glass-filament at 8° 35 a.m to near bottom of basal half of plumule & traced movement on Horizontal glass in darkness, & the tracing showed that this knob or summit summit of arc began at once to bend laterally upwards through apo-geotropism. The line traced was very slightly zig-zag, showing only a trace of circum-nutation. The movement was so quick that by 10° 30' P.m. the arch stood almost vertical very highly inclined. This lateral upward movement then became next day Jan. 3d much slower, so that by 3° P.m, not quite vertical, but now had grown so much that the arch was quite distinct as an arch, but with the tip of plumule still within Coats of seed. (N.B with this bean & that over page, I had to fix filament anew early on morning of Jan 3d' at base of basal 1/2 of plumule, for owing to growth of basal part of top of arch, the bead at end of filament approached the ground.) At 7° P.m arc vertical; at 10° 35' the line of movement was renewed — during the whole of this day movement slightly zig-zag)

(Jan. 4th Movement slightly zig-zag — during day it reversed its line of movement at 1° the upper part of plumule at right-angles to basal half. Late in afternoon moved very little, but tracing only slightly magnified At night glass filament fell off.)

(over)

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(2) B a second bean at same time treated & observed in every respect the same, but rather more advanced,— moved in same manner, but the line traced was hardly zig-zag, so that very little advanced sign hardly any sign of circum-nutation.

This one when filament was attached, had knob already inclined 30° or 35° above horizon; but the knob or arc was not vertical by 3° P.m. next day (Jan 3d. During this day 3d & 4th. moved in same general direction, but compared with other bean much mor slowly & shorter distance but in decidedly zig-zag course & for several hours in afternoon of 3d hardly moved at all. At 7° P.m. arc almost vertical

(Jan 5th. tip of plumule still within coats of seed; this bean has weak constitution or is suffering.— Moved card so as to magnify more, & began 9°. 8' am fresh tracing on Horizontal glass in darkness.

Continued to trace movement all the 5th, 6th & 7th till 5° 30' P.m.— The movement was in same general course & seemed due to basal part of plumule moving back from distal position & to the arc becoming vertical or even mor than vertical for bean itself was a little inclined. The line was occasionally zig-zag, which is the sole evidence of nutation. Bean evidently very sick, for tip of plumule still within coats of bean.