D aval lias and the Petiole of Lygodium . 501 
In the origin of each of the secondary branches a protoxylem of the 
primary branch elongates and divides (Text-fig. 2, E 2 » 3 ), supplying a single 
protoxylem, which doubtless later divides into two, to the secondary trace. 
In this and higher branchings the plane of the branch is practically parallel 
to that of the mother axis (Text-fig. 2, E, f). 
Lygodium dichotomum. The xylem of the petiolar trace (Text- 
fig. 4, B) has a deep adaxial indentation so as to make it almost three-lobed. 
Text-fig. 5. Lygodium vohibile. A. Habit sketch, b. Diagrammatic transverse section of 
petiolar trace, c. Departure of xylem strand to primary branch of petiole, d 1 , d 2 . Departure of 
xylem strand to secondary branch of petiole. 
The abaxial projection has a wide sinus, and there are two distinct proto- 
xylems facing one another, one on each tooth. This interpretation is 
confirmed by the presence of thick-walled sieve-tubes in the sinus in 
contact with the tracheae of the metaxylem. The position of the two 
lateral protoxylems and the distribution of the phloem are exactly as 
in L. japonicum. * 
Branches of the trace of the first (Text-fig. 4, c) and subsequent 
M m 
