8 m. for each revolution; and none of
the revolutions varied much from this rate. The revolving movement
continues as long as the plant continues to grow; but each separate
internode, as it becomes old, ceases to move.
To ascertain more precisely what amount of movement each internode
underwent, I kept a potted plant, during the night and day, in a
well-warmed room to which I was confined by illness. A long shoot
projected beyond the upper end of the supporting stick, and was
steadily revolving. I then took a longer stick and tied up the
shoot, so that only a very young internode, 1.75 of an inch in
length, was left free. This was so nearly upright that its
revolution could not be easily observed; but it certainly moved, and
the side of the internode which was at one time convex became
concave, which, as we shall hereafter see, is a sure sign of the
revolving movement. I will assume that it made at least one
revolution during the first twenty-four hours. Early the next
morning its position was marked, and it made a second revolution in 9
hrs.; during the latter part of this revolution it moved much
quicker, and the third circle was performed in the evening in a
little over 3 hrs.
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