CONTENTS xiii 



PAGE 



IT. Secretory Organs .... . 487 



A. Hydathodes - 487 



1. Structure and Arrangement of Hydathodes 487 



2. Function and Importance of Hydathodes - - -197 



B. Digestive Glands ........ 502 



1. The Digestive Glands of Carnivorous Plants - 502 



2. The Digestive Glands of Embryos - - 505 



C. Nectaries ----- ... 507 



D. Oil-, Resin-, Mucilage- and Gum-secreting Glands - 511 



1. External or Dermal Glands - - - - 511 



2. Internal Glands (Secretory Sacs or Reservoirs) - - 516 



E. Secretory Ducts and Passages (Oil-, Resin-, Mucilage- and 



Gum-passages) - - - - 521 



III. Excretory Reservoirs ------- 526 



1. Resin- and Oil -sacs ------- 526 



2. Tannin-sacs -------- 528 



3. Enzyme-reservoirs - - - - - 529 



4. Crystal-sacs - 530 



5. Cystoliths 536 



6. Deposits of Silica - ... 537 



IV. The Secretory and Excretory Systems in the Thallophyta 539 

 V. Ontogeny of Secretory and Excretory Organs - - 540 



CHAPTER XI. 

 THE MOTOR SYSTEM. 



I. General Considerations - 542 



II. Passive Motor-tissues -------- 544 



A. Flying-hairs and, Flying -tissues ----- 544 



B. Floating -tissues - ...... 548 



III. Active Motor-tissues - - - 549 



A. Hygroscopic or Imbibition Mechanisms ... - 549 



B. Cohesion Mechanisms ....... 557 



C. Living Motor-tissues ....... 560 



CHAPTER XII. 

 THE SENSORY SYSTEM. 



I. General Considerations - - - - - - - 571 



