20 s.; and this rapid movement, accompanied by incessant
oscillations, was a wonderful spectacle when beheld under the microscope.
The absence of light, for at least a day, does not interfere in the least
with the circumnutation of the hypocotyls, epicotyls, or young shoots of
the various dicotyledonous seedlings observed by us; nor with that of the
young shoots of some monocotyledons. The circumnutation was indeed much
plainer in darkness than in light, for if the light was at all lateral the
stem bent towards it in a more or less zigzag course.
Finally, the hypocotyls of many seedlings are drawn during the winter into
the ground, or even beneath it so that they disappear. This remarkable
process, which apparently serves for their protection, has been fully
described by De Vries.* He shows that
* 'Bot. Zeitung,' 1879, p. 649. See also Winkler in 'Verhandl. des Bot.
Vereins der P. Brandenburg,' Jahrg. xvi. p. 16, as quoted by Haberlandt,
'Schutzeinrichungen der Keimpflanze,' 1877, p. 52.
[page 109]
it is effected by the contraction of the parenchyma-cells of the root.
Pages:
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196