CONTENTS. 



CHAPTER 



X. Structure of the Coniferous Stem , . , . . .137 



Fig. 50. Sectional view of young stem of Pinus sylvestris . 138 

 ,, 51. Cross-section through resting cambium, etc., of P. 



sylvestris . ._-.. . . . . 141 



52. Origin of wood and bast from cambium in P. 



sylvestris * . . '. . '-.'.. V . 142 

 ,, 53. Limits of year's wood, and resin passage in P. 



sylvestris , " . . . . . .144 



,, 54. Radial section of wood of P. sylvestris, with 



medullary ray * ... 146 



,, 55. Sieve-tubes and sieve areas of P. sylvestris . . 148 



56. Tangential section of wood of P. sylvestris . . 150 



,, 57. Sieve-plates of P. sylvestris ..... 151 



,, 57*. Resin passages in young bast of Hedera Helix . 152 



XI. Structure of the stem of the Lime. Study of tissue- 



elements by the maceration - method . Tyloses, or 



tracheal plugs. . . . . '. ".'. . . . 153 



Fig. 58. Diagram of cross-section of twig of Tilia . . 154 



,, 59. Cross-section through wood of Tilia . . . 155 



,, 60. Cross-section through bast of Tilia . : * t V: 156 



,, 61. Fragment of radial section through wood of Tilia 157 



62. Tangential section through wood of Tilia . . 158 



63. Isolated elements of wood and bast of Tilia . . 160 

 ,, 64. Tracheal plug (Tylose) of Robinia . . .162 



XII. Central Cylinder (stele), and secondary increase in thick- 



ness of Roots ...... , ". . .163 



Fig. 65. Cross-section of root of Allium Gepa . . .- 164 



,, 66. Cross-section of root of A corns Calamus . . 166 



,, 67. Cross-section of root of Iris florentina . . . 167 



,, 68. Cross-section of young root of Taxus bacca ta . 170 



XIII. The stele of the Pteridophyta ....... 172 



Fig. 69. Cross-section through a small stele of Pteris 



aquilina ........ 174 



,, 70. Cross-section of stem of Lycopodium complanatum 177 

 ,, 71. Cross-section (diagrammatic) through internode of 



-Equisetum arvense . , ) .179 

 ,, 72. Cross-section through vascular bundle of E. arvense 180 



XIV. Cork. Lenticels. Bark. . . . ^fr^V^v *\ - 182 



Fig. 73. Cork-development in stem of Sambucus nigra . 183 

 ,, 74. Cross-section through Lenticel of Sambucus nigra 184 



XV. Structure of foliage arid of floral leaves. Terminations of 



the vascular bundles. Fall of the Leaf -., . . .189 



Fig. 75. Surface sections of leaf of Ruta graveolens . . 190 



,, 76. Cross-section through leaf of Ruta graveolens . 192 



77. Cross-section through leaf of Fagus sylvatica . 195 



,, 78. Vascular bundle-ending in Impatiens parviftora . 200 



