xxv] 



ANATOMY 



223 



nodes a ridge of xylem projects internally, which becomes more prominent 

 at subsequent nodes, and is continued forwards into the internode further 

 and further at successive nodes, till that of one node eventually connects 

 with a similar xylem-dilatation of the next node (Fig. 498, A). A continuous 

 central strand is thus produced, which is connected at the nodes with the 

 outer cylinder. The process thus described may then be repeated in that 

 central strand: it thus becomes cylindrical, forming the second vascular 

 ring, which is still connected at the nodes with the foliar system (Fig. 498, B), 

 and a fresh strand may originate internally from it : this in its turn becomes 

 cylindrical in the most advanced types, 

 but still maintains its connection with 

 the middle and outer rings in the 

 neighbourhood of the nodes. The 

 whole development is in fact an ex- 

 treme type of the elaboration of the 

 solenostele described by Gwynne- 

 Vaughan in other Ferns (Ann. of Bot. 

 xvii, p. 703). The smaller and more 

 lax species, M. sarmciitosa, with a rhi- 

 zome about 4 mm. in diameter, stops 

 short before this extreme complica- 

 tion is reached: it appears to settle down to a condition between (/i) and 

 {B) in Fig. 498, according to the observations of Compton (Fig. 499). All 

 these facts suggest that size has an influence upon the complexity of the 

 vascular structure. 



The leaf-trace as it passes up the petiole becomes a deeply inrolled meristele 

 in J\L pectinata, but less so in J/, sannentosa. Here the trace comes off as 

 that of Gleiclienia does (F^ig. 499, B, compare Fig. 478, p. 197). It possesses 

 three protoxylems, as in that genus, and the upper part of its petiolar 

 course shows features of the meristele strikingly like those of Gleichcnia, 

 but not so strongly contracted (Compton, I.e. Fig. 39). F^inally, the origin 

 of the pinna-traces is extra-marginal, as in Gleicheuia. 



The roots are found to be triarch. 



l*ig. 499. Stelar structure of Matoiua sarmen- 

 tosa, after Compton. A, an internode: B, 

 structure at a node, with leaf-trace. The 

 protoxylems are indicated by crosses. 



Spore-producing Members 

 The anatomical similarities thus disclosed between Matonia and Glei- 

 cheuia provoke comparison of their sori also. It will be found that while the 

 position and general plan of the sori is the same, there are differences in 

 man}' details. The sporangia of the sorus in Matonia, commonly six to nine 

 in number, form a simple ring-like series round the receptacle, and are 

 covered till maturit}' by a thick and leathery hemispherical indusium, 

 which is ultimately deciduous. The orientation of the sporangia is not 



