i ole) BOTANICAL GAZETTE [AUGUST 
connection with the number of rings. I have not yet found time 
to give them a careful study. In the plant of Ceratozamia, already 
referred to, the cells of the xylem are quite uniform, there being no 
trace of growth rings, and a similar condition was found in several 
stems of Zamia floridana. 
i. 
‘S 
Geta 
tt 
ER SLOSS ce 
225 = 
Wes 
o80,7 
F 
Fic. 18.—Dioon spinulosum: portion of large medullary ray, showing the tracheids 
indicated in tangential section at the tip of the large ray in fig. 12; somewhat above 
the scalariform tracheids are pitted tracheids of the secondary wood; the lower third 
of the figure shows part of the leaf trace bundle in the ray; many cells contain calcium 
oxalate crystals; X40. 
PHLoEM.—The phloem was overlooked by BRonGnrART, doubt- 
less on account of its great extent and the numerous bast fibers 
which makes it resemble the wood. A small portion of the xylem, 
the cambium, and asmall portion of the phloem of Dioon spinulosum 
are shown in fig. 17. The extent of the phloem is indicated in the 
photomicrographs (figs. 3, 4, and 8-10). In longitudinal section, 
especially in tangential section, the resemblance to the wood is 
