215 
Anatomy of the Opkioglossaceae. /. 
to one side of the incipient fourth leaf-gap ( 16 , 77). The internal endo- 
dermis, which has persisted as a more or less incomplete layer (ij c-i6) } 
now becomes localized as an arc internal to the departing fourth leaf-trace 
(/y, 18). It then dies out and plays no part in the actual departure of 
Text- FIG. 9. Selected transverse sections of plant F, showing the progressive changes in the stele 
and the endodermal relations from the basal to the adult regions. Description in text. 
this trace (79, 20 ), which follows the adult type, as do all the succeeding 
leaf-traces. Three traces depart in rapid succession, and then two roots 
are borne just below the meristematic region of the plant. 
This plant has thus a marked intermediate region between the basal 
