Pteridophyten. 307 



to be endoxylic. At the upper end of the swollcn leaf bases there 

 arc usually about nine groups of cavity parenchyma marking the 



Position of the protoxylem. In P, cordata the vascular band of the 

 leaf trace becomes divided by constrietion, fusing again higher up. 

 Each leaf base is adaxially subtended by a deep involution oi" the 

 surface, such as has already been noted in some Helicogyratae. The 

 stolons always originate in connexion with a leaf base and the 

 relative proportions of leaf base and stolon vary enormously. The 

 vascular Strand of a stolon-bearing leaf is more constricted than that 

 of an ordinary leaf and becomes crescentic with abaxial horns; in 

 its interior phloem, pericycle, endodermis and sclerenchyma oeeur 

 successively so that the stele is a solenostelic ring with slight lateral 

 horns. It opens abaxially and the portion between the horns departs 

 into the abortive leaf apex. In other cases in which the leaf apex 

 is still less important the vascular supply is mainly taken up in 

 supplying the stolon. The solenostele closes after the departure of 

 the Strand into the leaf apex but soon opens again to give off 

 adaxially the first scale leaf-trace. Stolons often correspond very 

 closely at their insertion in form and in position to leaf bases. A 

 stolon may give rise to a secondary stolon. At the point of junetion 

 and leaf the condition is comparable to that obtaining aecording to 

 Goebel (Organograph}*, Vol. 2) in some species of Utricularia in 

 which we get all transitions from foliage leaves to stolons. This is 

 true of Plagiogyria where the question seems to be one of balance 

 between the primordia of leaf and stolon the resulting strueture 

 assuming the form of the predominant partner. The leptosporangiate 

 sori of the genus are mixed; the annulus is complete and oblique 

 and the form of the sporangium is peculiar, resembling that of 

 Aneimia. 



The genus seems the simplest and the most primitive of the 

 Pterideae and recalls the Osmundaceae in the upright habit and 

 occasional dichotomy of the axis. Other characters regarded as 

 primitive are the absence of flattened scales, the relatively simple 

 venation, the approach in the anatomy to solenostely, the oblique 

 annulus with indeterminate stomium; the segmentation of the spo- 

 rangia, the tetrahedral form of the spores and the initially simple 

 sorus becoming mixed by later intercalation. Thus the genus and 

 the group Pterideae of which it seems to be the most primitive 

 member seem to be directly derived from the Simplices without 

 passing through a "mixed" phase. Isabel Browne (London). 



Charles, G. M., The anatomy of the sporeling of Marattia 

 alata. (Bot. Gaz. LI. p. 81-101. pls. 9—12. Feb. 1911.) 



The sudden transition from a solid to a tubulär stele is descri- 

 bed and compared whith the transition in other ferns. The origin 

 and course of the medullary system of bundles is illustrated by 

 photographs of modeis, and is found to differ from the condition in 

 the solenostelic ferns. The position of protoxylem varies in different 

 regions of both stem and leaf, and in some cases may be indistin- 

 guishable. Variation is also manifested in the meristems, which 

 ränge from a triangulär apical cell in young sporelings to meriste- 

 matic groups in older stems and roots. Mucilage canals generally 

 arise schizogenously, but the lysigenous mode may also be found. 



M. A. Chrysler. 



