Oxalis rosea: longitudinal section of a pulvinus on the summit of
the petiole of a cotyledon, drawn with the camera lucida, magnified 75
times: p, p, petiole; f, fibro-vascular bundle: b, b, commencement of blade
of cotyledon.
* 'Die Periodische Bewegungen der Blattorgane,' 1875.
** Batalin, 'Flora,' Oct. 1st, 1873
*** Pfeffer, ibid. p. 5.
[page 114]
without such aid, is reduced to the expansion of the cells not being
followed by growth in the first case, and being so followed in the second
case.
Dots were made with Indian ink along the midrib of both pulvinated
cotyledons of a rather old seedling of Oxalis Valdiviana; their distances
were repeatedly measured with an eye-piece micrometer during 8 3/4 days,
and they did not exhibit the least trace of increase. It is therefore
almost certain that the pulvinus itself was not then growing. Nevertheless,
during this whole time and for ten days afterwards, these cotyledons rose
vertically every night. In the case of some seedlings raised from seeds
purchased under the name of Oxalis floribunda, the cotyledons continued for
a long time to move vertically down at night, and the movement apparently
depended exclusively on the pulvini, for their petioles were of nearly the
same length in young, and in old seedlings which had produced true leaves.
Pages:
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204