Ontogeny. 
11 
Lindsay a -stage and the solenostelic condition are passed through, 
but the crowding or the elongation of the leaf-gaps eventually 
leads to their overlapping, and thus to the apparent breaking up of 
the solenostelic cylinder into separate strands (Figs. 98, 99, 100). 
Sometimes one or other stage is omitted, e.g., the solenostelic 
condition in Fig. 100, or the stele passes straight from the 
protostelic to the dictyostelic condition (Fig. 101), somewhat as in 
Marattiaceae. In the “ perforated ” types, gaps other than leaf-gaps 
begin to arise as the dictyostele increases in diameter. 
Fig. 99. Notho chlcena siniiata. Ontogenetic evolution of dictyostely 
through solenostely from the Lindsaya -type (amphiphloic protostely) by the 
development of ground-tissue pockets which are from the first in connexion to 
form a pith (C—F) within the internal phloem, and the subsequent overlapping 
of successive leaf-gaps. A, Amphiphloic protostely. F, Solenostely. H, 
Dictyostely. From Chandler. 
The only polycyclic form whose development has been worked 
out in adequate detail is Matonia pectinata , and here we find a 
complete series of stages, from the protostelic condition in the very 
young plant to the tricyclic solenostelic type in the largest rhizomes. 
The later stages of this ontogenetic evolution we have already 
traced, in the sixth lecture. 
