SUMMARY OF CONTENTS x i 



IV. The Development of the Plant under the Influence of Internal 



and External Factors 



CHAPTER I 



Periodicity in Vegetative Life 



a. Activity and rest, 341. 



b. Daily periodicity, 342 ; after-effect, 343. 



c. Annual periodicity, 343. 



1. In longitudinal growth. Trees. Leaf -formation, 344 ; causes of the 



periodicity, 345 ; root-formation, 346. Perennials, 346. Tropical plants, 347 . 

 Qualitative changes. Scale-leaves, 348 ; bracts, 349. 



2. In growth in thickness, 350. 



d. Periodicity in development as a whole, 351. 



CHAPTER II 

 Periodicity in Reproduction 



Definition of reproduction, 353 ; types of reproduction, 355. 



a. Causes of reproduction in lower plants, 355 ; examples, 356 ; general results 



of Klebs's researches, 357. 



b. Reproduction in the higher plants, 358. Reproduction in ferns. Alternation of 



generations, 358 ; apogamy and apospory, 359 ; accessory reproductive 

 organs, 359. Reproduction in flowering plants. Alternation of genera- 

 tions, 361 ; accessory reproductive organs, 362. Causes of reproduction. 

 Continuous vegetative growth, 362 ; causes of flower formation, 363 ; causes 

 of the formation of accessory reproductive organs, 365. 



c. Significance of reproduction, 365 ; general significance, 365 ; significance of 



fertilization, 366. Cessation of the check to development as a consequence 

 of fertilization, 367 ; deficiency of nuclein in the ovum, 367 ; deficiency of 

 chromosomes, 368 ; deficiency in kinoplasm, 369 ; parthenogenesis, 369 ; 

 stimuli to development, 370 ; merogeny, 371. Fertilization as amphimixis, 

 371. Hybrids, 372 ; (a) production, 372 ; appearance, 373 ; characters, 373 ; 

 (jS) second generation : segregation, 375 ; (y) its significance in estimating 

 the meaning of fertilization, 375. 



CHAPTER III 

 Heredity and Variation 



a. Heredity. Initials, 376. 



1. Heredity in unicellular types, 376. 



2. Heredity in multicellular types, 376 ; idioplasm, 377 ; idioplasm in the cell, 



377 ; idioplasm in the entire plant, 379 ; somatic and germ-cells, 379 ; 

 disappearance and origin of initials, 380. 



b. Origin of species. Theory of descent, 383 ; Darwinian theory, 384. 



1. Selection. Mode of action in formation of species, 384; definition of a 



species, 384 ; specific characters, 385 ; characters associated with adapta- 

 tion and organization, 386. Mode of action in adaptation, 386. 



2. Variation. Fluctuating variations, 387. Adaptation, 389; capacity for 



adaptation, 389 ; inheritance of acquired characters, 390. Mutation, 393. 



