observed by us, and we did not then know how far the circumnutation of the
different parts was affected by light. Young seedlings were therefore kept
in complete darkness except for a minute or two during each observation,
when they were illuminated by a small wax taper held almost vertically
above them. During the first day the hypocotyl of one changed its course 13
times (see Fig. 9); and it deserves notice that the longer axes of the
figures described often cross one another at right or nearly right angles.
Another seedling was observed in the same manner, but it was much older,
for it had formed a true leaf a quarter of an inch in length, and the
hypocotyl was 1 3/8 inch in height. The figure traced was a very complex
one, though the movement was not so great in extent as in the last case.

The hypocotyl of another seedling of the same age was secured to a little
stick, and a filament having been fixed to the midrib of one of the
cotyledons, the movement of the bead was traced during 14 h. 15 m. (see
Fig. 10) in darkness. It should be noted that the chief movement of the
cotyledons, namely, up and down, would be shown on a horizontal glass-plate
only by the lines in the direction of the midrib (that is,
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up and down, as Fig. 10 here stands) being a little lengthened or
shortened; whereas any lateral movement would be well exhibited. The
present tracing shows that the cotyledon did thus move laterally (that is,
from side to side in the tracing) 12 times in the 14 h. 15 m. of
observation. Therefore the cotyledons certainly circumnutated, though the
chief movement was up and down in a vertical plane.

Fig 10. Brassica oleracea: circumnutation of a cotyledon, the hypocotyl
having been secured to a stick, traced on a horizontal glass, in darkness,
from 8.15 A.M. to 10.30 P.M. Movement of the bead of the filament magnified
13 times.