16 THE EVOLUTION OF CONTINUITY 



FIG. Pi.SE 



35. The evolution of strobilar continuity 104 



36. astrea pallida, a compound cobal 105 



37. Cross-section of a simple cobal . . - 106 



38. Sectional diagram comparing Starfish with Medusa . . 108 



39. A suggestion concerning the evolution of Echinoderms . 109 



40. A suggestion concerning the evolution of Starfish . . 110 



41. The Earthworm's central nervous system . . . .115 



42. Significance of Earthworm's Continuity. The "heabts" . 117 



43. The evolution of the nervous system of Earthworm . . 120 



44. (a) The probable nervous system of the Phanerogam. 



(6) Diagrammatic Node of Ranvier 124 



45. The nervous system of a Sea-anemone 126 



46. The main road of Continuity's evolution, and the side- 



paths, with reference to aqueous and terrestbial 



environment 152 



47i The possible manner of evolution of the tubular zooid . 165 



48. The different forms of sexual structure in marine zooidal 



colonies 172 



49. Suggested homologies connected with Gymnosperm evolution 174 



50. Site of sexual organs in medusiform gonophores . . .176 



51. Significance of sexual parts of Angiosperm flower . . 176 



52. The significance of the perianth 177 



53. Diagram of suggested theory of plant-evolution. . .178 



54. The development of Aubelia 181 



55. The gills of the typical Fish 182 



56. The branchial circulation of typical Fish . . . .183 



57. (a) Plan of medusoid "circulatory system." (6) The mul- 



tiplication of this in continuity, (c) The circulatory 

 system of s^nuris 184 



58. Mouth-formation, etc., in primitive Fish 186 



59. How the development of the primitive piscine mouth would 



entail a closed cibculatory system 188 



60. Formation of mouth and gill-clefts in primitive Fish . 189 



61. The evolution of the segmental nerve-chain .... 192 



62. Evolutionary significance of the plans of the Inver- 



tebbate and vertebrate nervous systems . . . .194 

 63-65. The evolution of the Atypical Fish . . . 197, 198, 199 



66. Plan of a Cephalopod 200 



67. Table of the Periodic Law 208 



68. Effects of water-pressure on the developing evolving 



primitive Fish 225 



69. The Fish's cross-section 226 



70. Repulsion feom one direction is equivalent to attbaotion 



in an opposite one 231 



71. 72. Cobbection of deviation in the evolving Fish . 232 233 



73. The main dibections taken by light-waves passing to the 



primitive Fish's brain 234 



74. The coubse of fibres in human optic tracts .... 235 



