CONTENTS 



CHAPTER PAGE 



I. INTRODUCTORY 1 



Angiosperras and Gymnosperms contrasted, 1 Sperraatophytes 

 not a natural group, 3 Monocotyledons and Dicotyledons con- 

 trasted, 4. 



II. THE FLOWER 8 



Definition of a flower, 9 Origin of floral leaves, 9 Tendencies 

 in the evolution of the flower, 10 Organogeny of the flower, 16 

 Dioecism, 20 Morphology of floral members, 22 Stamen, 23 

 Carpel, 24. 



III. THE MICROSPORAXGIUM 27 



Origin from periblem, 27 Cauline microsporangia, 28 Number 

 of microsporangia, 29 Time of formation, 30 Development. 

 32 Archesporium, 32 Parietal layers, 34 Tapetum, 36 

 Mother-cells, 38 Dehiscence, 41 Line of demarcation between 

 sporophyte and gametophyte, 41. 



IV. THE MEGASPORAXGIUM 46 



Origin from periblem, 46 Cauline ovules, 46 Foliar ovules. 50 

 Morphological nature of ovule, 51 Time of development of 

 megasporangia, 52 Development of ovule, 53 Archesporium, 

 57 Parietal cells, 62 Mother-cell, 66. 



V. THE FEMALE GAMETOPHYTE 71 



The tetrad, 71 Number of megaspores, 76 Reduction of chro- 

 mosomes, 80 The functioning megaspore, 84 Number of em- 

 bryo-sacs, 86 Germination of megaspore, 87 Variations in 

 history, 89 Egg-apparatus. 93 Synergids, 94 Fusion of polar 

 nuclei, 95 Antipodal cells, 96 Enlargement of embryo-sac, 103 

 The nutritive jacket, 103 Haustoria, 104 The mechanism 

 for nutrition, 108. 



VI. THE MALE GAMETOPHYTE 121 



The tetrad, 121 Number of microspores, 125 The nuclear divi- 

 sions of the pollen mother-cell, 126 The microspores, 131 Ger- 

 mination of microspore, 132 Division of generative cell, 135 

 The male nuclei, 136. 



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