io8 Dr. W. C. Williamson oji 



Medulla Present. 

 Transverse. 



K.— p. 495, Figs. 3 and 4* C.N. 434. 



Primary Xylem Cylinder. 



K.— p. 495, Fig. 3 and 4» C.N. 434. 



Cortex — Middle. • 



K.— p. 495, Fig. 3, C.N. 434. 



Medulla. 

 Vertical. 



See C.N. 435 and 448E and 448D not yet figured. 



Protozylem. 



See 435. The vertical threads of the Tracheids now very conspicuous. 



Still Larger Branches. 



See C.N. 454 and 456 A. for transverse sections of the medulla, 

 primary xylem, perfect innermost, and most of the outer middle 

 cortex, and leaf-traces. The inner middle cortex has disappeared. 

 For large leaf-traces see 448 A. For vertical sections of the 

 same specimens, shewing identical tissues, see C.N. 448B. and 

 C. and D. Another section, 448D., shews the origin and course 

 of the leaf-traces. C.N. 448F. shews the elongated spaces pro- 

 ducing the large openings seen in the innermost cortex of 456A., 

 an anomalously large branch. 



K.— p. 496, Fig. 5, C.N. 450. 



Medullary area d. Exogenous secondary xylem i, outer middle cortex e, 

 prosenchyma of cortex h. This section, though its medulla and 

 its primary xylem cylinder have a greater diameter than is seen 

 in much older stems, is nevertheless younger than others yet to 

 be referred to, as is evidenced by the comparatively rudimentary 

 state of its secondary xylem strand i. 



Matured Arborescent Stems. 



These are fully 20 inches in diameter. The only tissues preserved iu 

 them external to the xylem strand are an external layer of 

 prosenchyma two Inches thick, which, when perfect, had appa- 

 rently a much greater diameter. 



Primary Xylem Strand. 

 MedtiUa. 



K. — p. 497, Fig. 6d. See C.N. 451 and 452 for the medullary spaces 

 from which the tissues have disappeared. 



Primary Trachael Cylinder. 



K. — p. 497, Fig. 6a and 6Aa. See C.N. 451-452. 

 Secondary Xylem Strand. 



K. — p. 497, Fig. 6i and 6Ai. See C.N. 451-452. 



Halonial Branch. 

 Transverse. 



M.— p. 466, Fig. 21, C.N. 458. 



Primary Trachael Strand. 



M.— p. 466, Fig. 2ia, C.N. 458. 



