60 DESCRIPTIVE INDEX TO THE PLATES. 



TIG. PLATE PAGE 



46. V. Transverse section of a rootlet cushion below the base of a rootlet. Vascular 



rootlet bundle,/". Small cells of the rootlet cushion, h. Zone of large cells 

 investing the rootlet cushion, h'. X 20 . . . .26 



47. V. Similar section to 46, only partly invested by some of the tissues of the root-cortex. 



Small cells of the rootlet cushion, h. Investing zone of larger cells, k'. Pro- 

 senchymatous cells of the root-bark seen in tangential section, e. x 20. 

 Cabinet, No. 807 . . . . . . .26 



48. V. Central portion of Tig. 47, further enlarged. Eootlet bundle, /. Phloem portion 



of the bundle,/'. Cellular investment of the bundle,/"', x 200 . . 26 



49. V. Some of the prosenchymatous cells of Fig. 47, e, undergoing fission by horizontal 



septa, x 40 . . . . . .20 



50. X. Minute branching tubular cells investing the Burface of the conical extremity, h', of 



the rootlet cushion, seen in the longitudinal rootlet sections, e.g. PI. X, fig. 43 i 27 



51. IX. Transverse section of a rootlet made about half way up the conical portion, ti, of 



the rootlet cushion. The outermost parenchyma of the root-bark, d. The 

 cortical layer of the rootlet, g. The second cellular layer of the rootlet very 

 rarely preserved, g'. Section of the small cells of the rootlet cushion, h. Boot- 

 let bundle and its sheath,/, x 50. Cabinet, No. 821 . . 27 



52. IX. Centre of Pig. 51. Xylem portion of the rootlet bundle,/. Phloem area of the 



bundle,/'. Bundle sheath,/" . . . . .28 



Small portion of the longitudinal section of a young rootlet bundle. Vascular 



bundle,/. Cells of the bundle sheath,/',/", x 100. . . .28 



Transverse section of a rootlet bundle with its bundle cylinder. Very small 



Tracheids at the point of departure of the monarch rootlet bundle,/,/". Bundle 



cylinder,/', x 100. Cabinet, No. 831 . . .29 



A second rootlet bundle, like 54. x 100. Cabinet, No. 829 . . . 29 



A third rootlet bundle, like Fig. 54. x. 100. Cabinet, No. 775 . . 29 



Vascular bundle,/, and part of the bundle cylinder,/", of a larger and older rootlet. 



Point of departure of the monarch bundle,/'. X 100. Cabinet, No. 836 . 29 

 Bootlet bundle,/, and its cylinder,/", of a yet older rootlet, x 100 . . 29 



Eootlet bundle,/ with part of its monarch initial vessels at/', but with two others 



yet deeper amongst the cells of the bundle cylinder at/'" . . .29 



60. XL Bootlet bundle, with part of its bundle cylinder,/". The more receutly added of 



the vessels of the bundle,/ radiate from the monarch point of departure at 



/' X 100 . . . . . . .30 



61. XI. A second rootlet bundle, like Fig. 60, with its initial vessels at/', and a small 



portion of its cylinder at /". Here again the vessels of the older part of the 

 bundle are non-radial ; the younger additions are disposed radially. X 100, 

 Cabinet, No. 651 . . . . . . .30 



62. XL Transverse section of a very young bundle,/, with its phloem elements preserved 



at/'". Bundle cylinder,/" . . . . . .32 



63. XL Transverse section of a rootlet about to dichotomise. Inner border of the cortical 



zone of the rootlet, g. Fistular cavity of the rootlet, g'. Two bundles,//, each 

 surrounded by its bundle sheath or cylinder,/',/', resulting from the division 

 of one single bundle, x 75. Cabinet, No. 862 . . . .32 



64. XIII. A natural cast of the medullary cavity of a Stigmarian root, the superficial, longi- 



tudinal ridges of which represent the prolongations of the medulla into the 



53. 



IV. 



54. 



XL 



55. 



XL 



56. 



XL 



57. 



XL 



58. 



XL 



59. 



XL 



