Vol. 69.] 



THE STRUCTURE OE DADOXYLON KAYI. 



455 



Fig. 6. — Dadoxylon kayi, 

 sp. nov. Transversa 

 section, showing the tra- 

 cheides with two medul- 

 lary rays. X -f (J. 



ball ' material. Attempts have been made to obtain sections 

 through the pith, but without much success, for the preservation 

 appears to be less perfect and compact in this region. The material 

 here tends to crumble, and to break up, and for this reason no 

 very reliable or definite information can be obtained with regard 

 to the nature of the pith or the structure of the adjoining tissues. 

 A transverse section of the stem (fig. 6) shows that true rings of 

 growth are absent, though false rings, 

 impcrsistent when traced laterally, fre- 

 quently occur. These arc probably due 

 to imperfections in the preservation, 

 and doubtless were not originally a 

 natural feature. 



The Avood is very dense (fig. G), the 

 tracheides as seen in transverse section 

 being small, from 0*037 to 0'051 mm. 

 across, and more or less rectangular or 

 square in form. Bordered pits are 

 sometimes seen on their walls. A 

 marked feature, however, of the wood is 

 the great abundance of the uniseriate 

 medullary rays. One ray sometimes 

 occurs between each row of tracheides, 

 and often between each two or three 

 rows. In other cases a larger number 

 of rows are frequently included between two rays. 



Fig. 7. — Radial section of D. kayi, „ . 7 7 . 



showing the tracheides, ivith, in Fl °; 8 --^. ( J reath d enlarged 



some cases, multiseriate bordered ™, °f ? art °* *teich*d 



pits on the radial walls, and a of J), kayi, as seemn radial 



single medullary ray, many cells se ? wn > ™ ltJl t thre 7 e r ? w *.°f 



in height. x 46. alternating bordered pits. 



x 387. 



In radial section (fig. 7) the tracheides are seen to be very long, 

 and they measure 0*05 mm. across. The pits on their radial walls 

 Q.J.G.S. No. 275. 2h 



