CONTENTS, IX 



of light do not correspond with its intensity — Etttcts of previous 

 illumination — Time required for the action of light — After-effects 

 of light — ^Apogeotropism acts as soon as light fails — Accuracy 

 with which plants bend to the light — This dependent on the 

 illumination of one whole side of the part — Localised sensitive- 

 ness to light and its transmitted effects — Cotyledons of Phalaris, 

 manner of bending — Results of the exclusion of light from their 

 tips — Effects transmitted beneath the surface of the ground — 

 Lateral illumination of the tip determines the direction of the 

 curvature of the base— Cotyledons of A vena, curvature of basal 

 part due to the illumination of upper part— Similar results with 

 the hypocotyls of Brassica and Beta — Radicles of Sinapis aphelio- 

 tropic, due to the sensitiveness of their tips — Concluding remarks 

 and summary of chapter — Means by which circumnuiation has 

 been converted into heliotropism or apheliotropism Page 449-492 



CHAPTEE X. 



Modified Ciecumitdtation : Movemekts excited by 

 Gbavitation. 



Means of observation — Apogeotropism — Cytisus — Veibena — Beta 

 — Gradual conversion of tiie movement of circumnutation into 

 apogeotropism in Eubus, Lilium, Phalaris, Avena, and Brassica 

 — Apogeotropism retarded by heliotropism — Effected by the aid 

 of joints or pulvini — Movements of flower-peduncles of OxaUs — 

 General remarks on apogeotropism — Geotropism — Movements of 

 radicles — Burying of seed-capsules — Use of process — Trifolium 

 subteiTaneum — Arachis — Amphicarpasa — Diageotropism — 

 Conclusion 493-522 



CHAPTEE XL 



liOCALisED Sensitiveness to Gravitation, and itb Transmitted 

 Effects. 



jcneral considerations — Vicia faba, effects of amputating the tips of 

 the radicles — Regeneration of the tips — Effects of a short ex- 

 posure of the tips to geotropic action and their subsequent 

 amputation — Effects of amputating the tips obhquely — Effects 

 of cauterising the tips — Effects of grease on the tips — Pisum 



