1914] PETRY—OPHIOGLOSSUM PENDULUM 185 
3 or 4 tracheids up to 5.4 mm. in the case of the strand concerned 
in the closure of the gap of the fifteenth leaf, as shown in fig. 12. 
A cross-section of one of the strands is shown in fig. 13; they con- 
sist of xylem and parenchyma, without a trace of phloem. The 
largest show 30-40 tracheids in cross-section; 8-12 tracheids is 
the usual size. No protoxylem can be identified; the tracheids 
all resemble those of the cylinder. 
Fic. 13.—Detail of a medullary strand; 236 
in only one other rhizome was anything of this nature observed. 
This specimen is from Samoa, and has only three leaves; the base 
'S preserved and shows its origin from a bud. At the level of the 
second leaf a small strand, consisting of a few tracheids only, arises 
* * procambium at a short distance from the inner surface of the 
cylinder. It very soon fuses with the cylinder but remains evident 
“$ @ ridge for a considerable interval. Fron the point of its 
“ppearance to that of disappearance is about 0.35 mm. 
