GENERAL CONSIDERATIONS ON THE MOVEMENTS AND GROWTH OF SEEDLING PLANTS.
Generality of the circumnutating movement--Radicles, their circumnutation
of service--Manner in which they penetrate the ground--Manner in which
hypocotyls and other organs break through the ground by being arched--
Singular manner of germination in Megarrhiza, etc.--Abortion of cotyledons-
-Circumnutation of hypocotyls and epicotyls whilst still buried and arched-
-Their power of straightening themselves--Bursting of the seed-coats--
Inherited effect of the arching process in hypo-
[page vi.]
gean hypocotyls--Circumnutation of hypocotyls and epicotyls when erect--
Circumnutation of cotyledons--Pulvini or joints of cotyledons, duration of
their activity, rudimentary in Oxalis corniculata, their development--
Sensitiveness of cotyledons to light and consequent disturbance of their
periodic movements--Sensitiveness of cotyledons to contact...Page 67-128
CHAPTER III.
SENSITIVENESS OF THE APEX OF THE RADICLE TO CONTACT AND TO OTHER IRRITANTS.
Manner in which radicles bend when they encounter an obstacle in the soil--
Vicia faba, tips of radicles highly sensitive to contact and other
irritants--Effects of too high a temperature--Power of discriminating
between objects attached on opposite sides--Tips of secondary radicles
sensitive--Pisum, tips of radicles sensitive--Effects of such sensitiveness
in overcoming geotropism--Secondary radicles--Phaseolus, tips of radicles
hardly sensitive to contact, but highly sensitive to caustic and to the
removal of a slice--Tropaeolum--Gossypium--Cucurbita--Raphanus--Aesculus,
tip not sensitive to slight contact, highly sensitive to caustic--Quercus,
tip highly sensitive to contact--Power of discrimination--Zea, tip highly
sensitive, secondary radicles--Sensitiveness of radicles to moist air--
Summary of chapter.
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