SOME FEATURES IN THE ANATOMY OF THE MAL VALES 
241 
plant, on either side of which appears the thin-walled portion of the 
stem, consisting of vessels like those already described for Tilia. The 
central portion represents the thick-walled portion with its libriform 
fibers, and rectangular parenchyma cells with simple pits. 
Figure 5 represents a transverse section of Fremontia californica 
Torr., which shows a striking resemblance to the thick-walled portion 
of Hibiscus, except for the presence of vessels. In this section paren- 
chyma appears as thin-walled light cells, and darker ones where the 
cross wall is retained with its typical simple pitting. Figure 6 shows a 
radial section with thick-walled fibers, and diffuse parenchyma whose 
cross walls form rectangular cells. 
Having presented the anatomical features of the three species, a 
discussion of their significance is desirable. The presence of diffuse 
parenchyma in Hibiscus and Fremontia, and the first annual ring of 
Tilia, with a reduction to tangential bands in the latter, shows that 
evidently the first two mentioned are more primitive since they do not 
show this characteristic reduction. 
It may be advisable just to mention some of the characters found 
in the herbaceous forms of the Malvales. There is in all, naturally, 
a great reduction of the xylem tissue, which is brought about by the 
transition of fibers to wood parenchyma. 
The New Zealand species of Aristotelia DC, shown in transverse 
section in figure 7, presents a departure from the characteristic diffuse 
type of parenchyma distribution, since storage cells occur only at the 
end of the annual ring, three terminal cells may be seen in the center 
of the figure, differentiated from the fibers by thin walls and simple 
pitting. Figure 8 represents a tangential section from the same ma- 
terial including the end of the annual ring. In this section a single 
terminal parenchyma cell is noticeable. The other structural features 
of the wood are not especially different from those found in Hibiscus 
and Fremontia. 
Turning now to the Fagaceae, which show conditions very similar 
to those found in the species just described, figure 9 represents a 
transverse section of Fagus grandifolia Ehrh. The rays are of two 
types and are diffuse, as is also the parenchyma, which appears as 
thin-walled cells freely scattered throughout the wood. In radial 
section, figure 10, the parenchyma appears as vertical rows of thin- 
walled cells, which have been formed from the fibers by septation. 
Conditions similar to those found in Aristotelia appear in a South 
