LIST OF ILLUSTRATIONS xxi 



FIG. PAGE 



52. Hydra, nematocyst and nerve-cell 228 



53. Hydra viridis, ovum 235 



54- BougainviUea ramosa 238 



55. Diagrams illustrating derivation of Medusa from Hydranth . 242 



56. EncopcUa campanularia, muscle fibres and nerve-cells. . . . 245 



57. Laomedta flexuosa and Endendrinm ramosum, development . 249 



58. Diphyes campanulata 252 



59. Porpita pacifica and P. mediterranea 253 



60. Spermatogenesis in the Mole-Cricket 256 



61. Ovum of Toxopneustes lividns 259 



62. Maturation and impregnation of the animal ovum 260 



63. The gastrula 265 



64. Pandorina morum 266 



65. Volvox globator 268 



66. Volvox globator 269 



67. Polygordius neapolifanus, external form 272 



68. Polygordius ncapolitanus, anatomy 274 



69. Polygordius neapoliianus, nephridium 285 



70. Polygordius, diagram illustrating the relations of the nervous- 



system 287 



71. Polygordius neapolitamts, reproductive organs ... . . 294 



72. Polygordius neapolitanus, larva in the trochosphere stage . . 296 

 73- Diagram illustrating the origin of the trochosphere from the 



gastrula 298 



74. Polygordius neapolitanus, advanced trochosphere 300 



75. Polygordius neapolitamts, larva in a stage intermediate be- 



tween the trochosphere and the adult 303 



76. Starfish, diagrammatic sections 310 



77. Crayfish, diagrammatic sections 316 



78. Mussel, diagrammatic sections . 321 



79. Dogfish, diagrammatic sections 326 



80. Mosses, various genera, anatomy and histology 333 



81. Funaria, reproduction and development 338 



82. Pteris and Aspidium, anatomy and histology 346 



83. Ferns, various genera, reproduction and development . . . 356 



