xii SUMMARY OF CONTENTS 



PART III 

 TRANSFORMATION OF ENERGY 



Conservation of energy in the organism, 397. 

 The forms of energy in the plant : 



1. Heat, 398 ; production of heat, 399 ; dependence on the state of development 



and on external factors, 399 ; relation to respiration, 400 ; sources, 400 ; 

 significance, 401. 



2. Light, 401. 



3. Electricity, 402. 



4. Mechanical energy, 403 ; sources, 403. Passive movements, 405 ; active 



movements and their classification, 405. 



I. Hygroscopic Movements 



Types of the movement, 406. 



a. Movements due to swelling. 



1. Swelling, 406. 



2. Movements due to swelling and contraction, 409 ; curvatures due to 



differential swelling of parts, 410 ; due to arrangement of cells, 410 ; 

 due to stratification of the cell- wall, 411; due to striation in the cell- 

 wall, 411. Twinings, 412. Torsions, 414. Biological significance of 

 these movements, 414. 



b. Movements due to the cohesion of imbibition water. Fern sporangia, 415 ; 



anthers, 416. 



II. Variation and Nutation Movements 



Osmotic pressure: amount, 418 ; action on the cell-wall, 419 ; movements due to 



osmotic pressure, 421. 

 Growth as a cause of movements, 421. 

 Performance of work during such movements, 421. 



CHAPTER I 

 Ejaculatory Movements 



Examples of ejaculatory movements, 422 ; tensions in single cells, 422 ; in 



tissues, 424. 

 Significance of external shocks, 426 ; autonomous and paratonic movements, 426 ; 



Cataseturn, 426 ; general remarks on movements due to external stimuli, 427 ; 



classification, 428. 



CHAPTER II 

 Paratonic Movements 



A. Tropisms (Directive Movements) 

 a. Geotropism, 429. 



i. In orthotropic organs. Proof, 430; occurrence, 431. Geotropic curvature. 

 In the root, 431; in the stem, 433 (amputated stems, 435); after the 

 cessation of longitudinal growth, 435 . Mechanics of curvature, 435. Signifi- 

 cance of gravity. Action of the stimulus, 436 ; duration of the stimulus, 

 437 ; intensity (439) and direction (439) of gravity. Preliminary effects 

 of the stimulus. Perception and reaction, 441 ; hypotheses as to perception 

 (NOLL, 442 ; NEMEC, and HABERLANDT, 443). Protoplasmic movement, 

 444 ; precedent chemical phenomena, 444. 



