Boodle . — Anatomy of the Schizaeaceae . 361 
arrangement. The petiole is upright and is continued into 
the climbing rachis which has indefinite growth, and bears 
pinnae at intervals. The pinna is usually quite short and 
stalk-like and divides dichotomously to produce secondary 
pinnae, but frequently at its apical region, i.e. at the fork, 
a bud-like body is produced, which afterwards is circinate, 
and then lengthens to produce a secondary rachis. The 
secondary pinnae may be simple or may be further divided 
dichotomously or pinnately. 
In all the genera of the Order the form of the leaves, 
venation, fructification, &c. are fully described in Prantl’s 
monograph. 
Lygodium, stem. 
The rhizome of Lygodium dichotomum , Sw., has a thick 
cortex, in which three zones may be distinguished. The 
outer cells are thin-walled and brown, and graduate into the 
thick-walled sclerotic elements of the middle part of the cortex. 
The latter cells have dark reddish-brown walls with numerous 
pits and distinct stratification. A similar brown colouring 
matter present in the walls is familiar in the sclerotic tissue 
of most Ferns and has been shown by Walter (’ 90 , p. 18) 
to be phlobaphene, which probably belongs to the group of 
humic substances. This colouring matter is slowly removed 
from the sclerotic tissue of Lygodium by the action of Eau de 
Javelle, and the decolourized walls then give the cellulose 
reaction with Schulze’s solution. This agrees with what 
Poirault (’ 93 , p. 127) found in certain other Ferns. Succeed- 
ing the sclerotic tissue abruptly is the third or innermost zone 
of the cortex, which consists of from three to five layers of 
rather thin-walled cells, whose walls are suberized. Many 
of these cells are slightly rounded off at the corners, when 
seen in transverse section. In a tangential section they are 
from two to five times as long as broad, and often show a 
chain of small oval intercellular spaces between their vertical 
walls, similar to those seen among the palisade-cells of some 
Angiospermous leaves. The intercellular spaces thus run in the 
