Radicles.--Glass filaments were fixed to two short radicles, placed so as
to stand almost upright, and whilst bending downwards through geotropism
their courses were strongly zigzag; from this latter circumstance
circumnutation might have been inferred, had not their tips become slightly
withered after the first 24 h., though they were watered and the air kept
very damp. Nine radicles were next arranged in the manner formerly
described, so that in growing downwards they left tracks on smoked
glass-plates, inclined at various angles between 45o and 80o beneath the
horizon. Almost every one of these tracks offered evidence in their greater
or less breadth in different parts, or in little bridges of soot being
left, that the apex had come alternately into more and less close contact
with the glass. In the accompanying figure (Fig. 52) we have an accurate
copy of one such track. In two instances alone (and in these the plates
were highly inclined) there was some evidence of slight lateral movement.
We presume therefore that the friction of the apex on the smoked surface,
little as this could have been, sufficed to check the movement from side to
side of these delicate radicles.
Pages:
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128