CONTENTS xi 



CHAPTEE XV. 



PAGE 



Special Sensitiveness and its Results . . 492 



Heliotropism ^^'"^ 



Geotropism .494 



Contact 



495 



Chemical stimuli ^"^"^ 



CHAPTER XVI. 



The Nervous Mechanism of Plants . . . 500 



CHAPTER XVII. 



Automatism — Rh"sthm . . . . 506 



Automatic movements ....••••• o07 



Ciliary motion '507 



Creeping movements of Myxomycetes 507 



Contractile vacuoles ... 508 



Rotation of protoplasm 508 



Rhythmic movements 509 



Periodicity 510 



Artificial rhythm ■ . • 511 



CHAPTER XVIII. 



Reproduction 512 



Vegetative reproduction 512 



Asexual reproduction by spores or gonidia .... 513 



Sexual reproduction by gametes ....... 514 



Alternation of generations ........ 514 



Evolution of sexuality ......... 516 



Fertilisation 517 



Pollination 518 



Dichogamy 519 



Diclinism 520 



Dimorphism and Triiiiorphism ....... 520 



Prepotency . . . . . . ' . . " . . . 521 



Cleistogamy .......... 521 



Hybridisation . . . . . ■ . . . . . 521 



Germination of seeds ........ 522 



Apospory, apogamy, and parthenogenesis 523 



