168, and Fig. 39, formerly given, p.
52); yet they moved a short distance towards the side where the taper was
held up. If we look at these diagrams, and suppose that the taper had been
held more on one side, and that the hypocotyls, still circumnutating, had
bent themselves within the same time much more towards the light, long
zigzag lines would obviously have been the result.
Fig. 169. Avena sativa: heliotropic movement and circumnutation of
sheath-like cotyledon (1 ? inch in height) traced on horizontal glass from
8 A.M. to 10.25 P.M. Oct. 16th.
Again, two seedlings of Solanum lycopersicum were illuminated from above,
but accidentally a little more light entered on one than on any other side,
and their hypocotyls became slightly bowed towards the brighter side; they
moved in a zigzag line and described in their course two little triangles,
as seen in Fig. 37 (p. 50), and in another tracing not given. The
sheath-like cotyledons of Zea mays behaved, under nearly similar
circumstances, in a nearly similar manner as described in our first chapter
(p.
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