PLATE V. 



Fig. 8. — Tangential section from a vascular cylinder, showing transverse sec- 

 tions of the primary medullary rays, V. Vascular rootlet bundles, f. X 5. 

 Cabinet, No. 771. (Pages 13, 14, 34, 35.) 



Fig. 13. — Transverse section of the primary medullary ray, Plate IX, fig. 12, 

 but made close to the cortical surface of the vascular cylinder, b. Vascular rootlet 

 bundle,/. First formed portion of the rootlet bundle, /'. Secondary medullary 

 rays, d. X 30. Cabinet, No. 856. (Pages 14, 23.) 



Fig. 16. — Transverse section of a young primary medullary ray. Vessels of 

 the xylem cylinder, b'. Cells of the medullary ray, b. Primary vessels of the 

 rootlet bundle, /'. Later formed vessels, /. Secondary medullary rays, d. X 14. 

 Cabinet, No. 824. (Pages 14, 23, 31.) 



Fig. 16a. — Transverse section of the vascular cylinder of a very young Stig- 

 maria. Cabinet, No. 773. X 5. (Page 15.) 



Fig. 46. — 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, hf. X 20. (Pages 26, 28.) 



Fig. 47. — 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, h'. Prosenchymatous cells of the root-bark seen in tangential section, e. 

 X 20. Cabinet, No. 807. (Pages 26, 28.) 



Fig. 48. — Central portion of Fig. 47, further enlarged. Rootlet bundle, /. 

 Phloem portion of the bundle, /'. Cellular investment of the bundle, /'". X 200. 

 (Pages 26, 28, 32.) 



Fig. 49. — Some of the prosenchymatous cells of Fig. 47, e, undergoing fission 

 by horizontal septa. X 40. (Page 20.) 



