De Candolle believes that the
tendrils differ in their homological nature in two of the tribes.
{29} From facts recently adduced, Mr. Berkeley thinks that Payer's
view is the most probable, namely, that the tendril is "a separate
portion of the leaf itself;" but much may be said in favour of the
belief that it is a modified flower-peduncle. {30}
Echinocystis lobata.--Numerous observations were made on this plant
(raised from seed sent me by Prof. Asa Gray), for the spontaneous
revolving movements of the internodes and tendrils were first
observed by me in this case, and greatly perplexed me. My
observations may now be much condensed. I observed thirty-five
revolutions of the internodes and tendrils; the slowest rate was 2
hrs. and the average rate, with no great fluctuations, 1 hr. 40 m.
Sometimes I tied the internodes, so that the tendrils alone moved; at
other times I cut off the tendrils whilst very young, so that the
internodes revolved by themselves; but the rate was not thus
affected. The course generally pursued was with the sun, but often
in an opposite direction. Sometimes the movement during a short time
would either stop or be reversed; and this apparently was due to
interference from the light, as, for instance, when I placed a plant
close to a window.
Pages:
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169