THE SEEDLING OF CERATOZAMIA 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY I15 
HELEN A. DORETY 
(WITH TWO FIGURES AND PLATES XII-XVI) 
The vascular anatomy of adult cycad stems is likely to be obscured 
by two sets of complications. One, called anomalous thickening, 
described by Von Mont (14) in 1832 in species of Encephalartos, 
is limited to certain forms; the other, the phenomenon of girdling, 
was described by KARSTEN (5) in Zamia muricata Willd. in 1856, 
and by Merrentus (8) in Cycas, Encephalartos, and Dioon in 1860. 
Since then it has been found in the three other genera investigated. 
In the seedling these complications are either absent altogether or 
are just being initiated, hence the selection of juvenile forms is proba- 
ly even more important in the anatomical study of cycads than in 
that of any of the other vascular plants. Anatomists have recognized 
this and have given us numerous descriptions, only the more pertinent 
of which need be cited here. 
In 1856 Karsten (5), in the work mentioned above, found that 
each of the cotyledons of Zamia receives only one bundle, which may 
branch ; that the central cylinder is broken up by parenchymatous 
communication between pith and cortex; and that in older stems, 
with the increase in the number of cauline strands, there is a corre- 
sponding increase in the number of bundles entering the leaves, 
because every bundle of the central cylinder contributes a trace. 
€ also observed the frequent anastomosing of the leaf traces reported 
by Von Moat, as well as the occurrence of girdling. , 
In 1884 BowEr (1) wrote a few descriptive notes on the seedling 
of Cycas Seemanni Al. Braun, He found the two cotyledons unequal 
Mm size and dissimilar in vascular anatomy. He says that while in 
Some there is a median bundle which extends the whole length of the 
cotyledon without branching, in others there are two equal bundles 
Rear the center. 
In 1887 Greco (4) reported anomalous thickenings in the root 
of this species, 
203] [Botanical Gazette, vol. 46 
