116 THE UNIVERSITY SCIENCE BULLETIN. 



Fig. 41. Longitudinal section of wood parenchyma from secondary 

 xylem of primary vascular bundle in region III of the stem. X 225. 



Fig. 42. Longitudinal section of pitted fiber tracheids from the secondary 

 xylem of a primary vascular bundle in region III of the stem. X 225. 



PLATE VIII. 



Fig. 43. Primary vascular bundle from region IV of the stem. Corres- 

 ponding parts lettered as in fig. 32. X 330. 



Fig. 44. Older leaf-trace bundle in the pericycle of the stem in region IV. 

 Corresponding parts lettered as in fig. 32. X 330. 



Fig. 45. Portion of cross section of the stem in region V, showing pri- 

 mary medullary ray cells which, in this region of stem and below, resemble 

 pith cells in shape and nature of cell walls: j, portion of primary vascular 

 bundle. X 225. 



Fig. 46. Longitudinal section of cells in a portion of the pericycle of the 

 stem in region III corresponding in location to the area of pericycle e", 

 fig. 9. X 225. 



Fig. 47. Portion of a cross section of the stem in region III: d, starch 

 sheath; e', outer area of pericycle; e", central area of the pericycle; n, active 

 arc of secondary meristem; /', bast fiber. X 330. 



Fig. 48. Portion of a cross section of the stem in region III; d, starch 

 sheath; e', outer area of the pericycle; e", central area of the pericycle; k, 

 leaf-trace bundle in the pericycle; n, active arc of secondary meristem. 

 X 330. 



Fig. 49. Portion of a cross section of the stem in region III: d, starch 

 sheath; e', outer area of the pericycle; e", central area of the pericycle; /, in- 

 ner area of the pericycle; m, anomalous xylem; n, active arc of secondary 

 meristem; s, anomalous phloem. X 330. 



PLATE IX. 



Fig. 50. Cross section of the stem between regions III and IV (location 

 shown in fig. 29, q"). Corresponding parts lettered as in fig. 6: I, inner 

 border of innermost anomalous xylem zone. X 48. 



Fig. 51. Cross section of the stem between regions III and IV (location 

 shown in fig. 29, q"). Corresponding parts lettered as in fig. 2: j, primary 

 vascular bundle; o, portion of area of one to six rows of very large parenchyma 

 cells of the primary cortex around the stem; p, anomalous xylem zone; q, 

 anomalous phloem zone; r, secondary medullary ray cell; s, anomalous 

 phloem; t, pericycle cells in outer part of area of tissue designated in this 

 article as an anomalous phloem zone; u, radial strip of anomalous xylem 

 located similar to the strip of xylem anastomosing from one anomalous 

 xylem zone to another in fig. 10, u; p', intercellular space; n", area of anoma- 

 lous tissue, including a radial strip of anomalous xylem and an anomalous 

 phloem group just exterior; o", long radial strip of anomalous xylem; p", area 

 of anomalous tissue, including a radial strip of anomalous xylem and a second- 

 ary medullary ray between the anomalous phloem groups. X 225. 



Fig. 52. Portion of cross section of stem in region IV; to show arc of 

 secondary meristem, n, becoming active to form the fourth xylem-phloem 



