THE LEAF-TRACE IN SOME PINNATE LEAVES. 
11 
similar to this, but the abaxial curve gradually dwindles and ultimately disappears 
in supplying the reinforcement to the second last pinna. The terminal pinna is 
supplied partly from the back of the hook of the adaxial strand, and partly from the 
abaxial tongue of this strand. The two portions move out independently of each 
other ; that coming from the hook soon divides into two strands by simple antero- 
posterior fission ; the other remains undivided, and the pinna-trace moves into the 
pinna as three strands. The process of supplying the pinnae ‘is very similar from one 
pinna to another along the length of the rachis ; but the last pinna has its abaxial 
strand derived from the adaxial strand of the rachis, while the earlier pinnae derive 
their abaxial curves from the abaxial curve of the leaf-trace. The pinna-trace of every 
pinna, however, resembles those of all the others in this respect, that its adaxial 
strands, derived extramarginally from adaxial leaf-trace strands, are reinforced by 
an abaxial system variously derived from the leaf-trace. 
The Leaf-Trace and Pinna-Trace of Dryopteris grandis (Pr.) C. Chr. 
Dryopteris grandis (Pr.) C. Chr. grows in the rain-forest on the Serra da Carioca. 
Its leaves are about eighteen inches long, with pinnatifid pinnse. The process of 
pinna-supply is very similar to that in Polystichum adiantiforme. The adaxial 
strand and the corner strand of the abaxial curve series both contribute to the pinna- 
trace (text-fig. 66, c, d, e ). And from the abaxial end of the contributing adaxial 
strand there is nipped off a small strand, before the back of the hook is separated 
(text-fig. 66). This strand may divide into two (text-fig. 6c). One of these usually 
unites, wholly or in part, with one of the strands of the group derived from the 
a b c d e f 
Tuxt-fig. 6. 
corner of the abaxial curve series (text-fig. 6d). The remaining strand or strands 
come into position between the adaxial corner of the abaxial curve series and the 
abaxial end of the adaxial strand (text-fig. 6e,/). Above the second last pinna the 
strand derived from the abaxial end of the adaxial strand fuses again with the 
adaxial strand, then separates again and passes out into the terminal pinna with a 
strand derived from the other extremity of the adaxial strand. Thus D. grandis 
corresponds closely with Polystichum adiantiforme with regard to the portions of 
the leaf-trace which branch to supply the pinna traces. The hooked back of the adaxial 
strand and the corner strand or strands of the abaxial curve series take part in the 
supply of the pinna. The abaxial tongue of the adaxial strand in Polystichum 
adiantiforme is used only to repair the abaxial curve series as the pinna-trace departs 
and to prepare for the nipping off of the next pinna-trace. In 1 ). grandis this 
