xiv LIST OF ILLUSTRATIONS 



FICORE PACE 



33-36. Life-History of a Fern 91 



37. Megasvorangiuu OT Selagindla 92 



38. Mega- and Microsporangia of Selaginclla ... 93 

 39-40. Dioon edide, Longitudinal Section of Ovules 94 

 41-45. Dioon edule, Development of Archegonium 98 



46. !Male Cone of Ceraiozamia loi 



47-49. Male Sporophylls of Ceraiozamia mexicana . . 102 



50. MiCROSPORANGiUM OF Dioon edule 103 



51. Sporangium of Angiopteris 103 



52-53. Microspores of Dioon edule 105 



54. Stangeria, Nucellus "with Pollen Tubes .... 107 



55. Stangeria, Pollen Tubes with Sperms 108 



56-57. Dioon edule, Body Cell \vith Blepharoplasts . 108 



58. Dioon edule, Young Sperms 109 



59. Cera/oza wrm, Photomicrograph OF Sperm .... 110 



60. D/o(7« edw/^, General View OF Fertilization . . . 114 



61. 5/a?i gem, Fertilization 119 



62. S/a/rger/a, First Division IN Fertilized Egg . . 122 



63. /)/<Jo» eJ«/e, Free Nuclear St.\ge OF Embryo . 123 



64. 5/a«gcrm, Free Nuclear Stage OF Embryo . . . 124 



65. S/cMgerm, Simultaneous Nuclear Division . . . 125 



66. Stangeria, Evanescent Walls of Embryo ....126 



67. 5/a«ger/fl, Early Walls IN Embryo 127 



68. ZamayZor/</a«a, Young Embryo 128 



69. Dioon edule. Cotyledon Stage of Embryo .... 130 



70. /J>/oow eJw/e, Section OF Seed 131 



71-73. Dioon edule. Germination of Seed 133 



74-76. Dioon, Margins of Leaflets 135 



77. Dioon spinulosum. Seedling 136 



78. Diagram of Geological Horizons 140 



79. Idealistic View of Primitive Seed Plant 143 



80. Cycadeoidca, Bisporangiatk Strobilus 144 



8 1. Cycfl^ rcDtf/M/a, Crown of Female Sporophylls . . 146 



82. Dioon edule, Female Cone 147 



83. Macrozamia Miquelii, Female Cone 148 



84. Zamiajloridana, Female Cone 149 



85-91. Female Sporophylls of Cycads 150 



