52 STRUCTURE AND LIFE-HISTORY OF HAY-SCENTED FERN. 



PLATE 7: 



47. Root-tip of Aspidium marginale^ longitudinal section; #, first periclinal wall; 



6, second .periclinal; <?, endodermis. X 210. 



48. Root-tip of Aspidium molle, longitudinal section; e, endodermis. X 210. 



49. Root-tip of Didymochlccna lunulata, longitudinal section; e, endodermis. X 210. 



50. Root-tip of Ceratopteris thalictroides, longitudinal section. X 210. 



51. Root-tip of Onoclea sensibilis, longitudinal section; , endodermis. X2io. 



52. Cortex of root of Dennscetdtia punctilobula, showing mycorhiza, <?; transverse 



section of root. X 210. 



53. Ditto. Longitudinal section. Entrance of fungus through a root-hair. X 210. 



54. Rootlet, transverse section. Pericycle dotted ; sextant walls heavy. X 210. 



55. Junction of pericycle of root and rootlet. X 210. 



56. Junction of xylem of root and rootlet; longitudinal radial section of root. 



X 200. 



57. Ditto; tangential to rootlet. X 200. 



PLATE 8: 



58. Two tracheids from the junction of the vascular bundles of root and stem. 



Macerated and teased out. X 210. 



59. Young root in longitudinal section of stem apex. From point marked 3 in fig. 



70. X 210. 



60. Longitudinal section of older root, about to pass out from stem; b, root-cap. 



From point marked 4 in fi<?. 70. X 210. 



61. Junction of root shown in fig. 60 with stem bundle. X 210. 



62. Sharply bent tracheid at junction of root and stem, from same section as fig. 99. 



X 210. 

 PLATE 9: 



63. Part of transverse section of stem. Area included in dotted lines at 2 in 



fig- 97- . 



64. Part of longitudinal section of stem. Area included in dotted line n in fig. 70. 



65. Ends of sieve-tubes of stem; macerated and teased. 



66. Diagram of node; longitudinal section of stem and leaf-base; If, vascular bundle. 



PLATE 10: 



67. Rhizome, transverse section. Photomicrograph. 



68. Vascular bundle of petiole, transverse section. Photomicrograph. 



69. Rachis of leaf, transverse section. Photomicrograph. 



PLATE n: 



70. Diagram of stem apex, longitudinal section, i, 9, dotted outlines of leaf rudi- 



ments, showing their position relative to the stem apex. 2, 3, 4, 7, 8, 

 location of root-tips of various ages (cf. figs. 59, 60). 5, beginning of 

 protophloem. 6, point where endodermis and pericycle are separated. 

 10, beginning of lignification in xylem. u, area drawn in fig. 64. 



71. Stem-initial in transverse section. X 210. 



72-75. Segmentation and sectioning in the apex shown in fig. 71. Segments num- 

 bered in order of age. 



76. Isolated cells of sclerotic medulla; macerated and teased. 



77. Ditto. 



78. End of scalariform tracheid of stem; macerated and teased. 



79. Ditto. 



80. Isolated cells of sclerotic cortex of stem; macerated and teased. 



81. Isolated cells of conjunctive parenchyma of stem; macerated and teased. 



82. Vascular bundle of stem and leaf, with leaf-shoot dissected out and viewed from 



the side; o, leaf-gap; m, leaf-shoot; tr, leaf-trace; u, anterior end of por- 

 tion of vascular bundle of stem. Drawn from nature by Miss M. E. 

 Rogers. 

 PLATE 12: 



83-87. Diagrams of successive cross-sections of a fork of a stem, with ventral leaf. 

 Dotted line indicates boundary between sclerotic and starchy tissues; 

 vascular bundle section-lined; /r, leaf-trace. 



88-92. Diagrams of successive cross-sections of rachis, showing departure of rib of 

 pinna. Dotted line bounds sclerenchyma; solid line is endodermis; 

 xylem is section-lined; , trace of pinna. Fig. 88 is lowermost, 92 upper- 

 most. 



