310 Pteridophyten. 



megasporangium, or several basal megasporangia followed apically 

 by microsporangia or whole cones may be microsporangiate or 

 megasporangiate or finally the two kinds of sporangia may be ar- 

 ranged indiscriminately; in the last mentioned case the sporangia 

 are more or less of the same size and neither kind attains any 

 great complexity; this distribution of the sporangia occurs almost 

 entirely in the group of 5. Martensii and is therefore associated 

 with relativety simple anatomical structure. Reduction to three 

 megaspores oceurs in several species and is normal in S. Bakeriana; 

 reduction to two is normal in 5. rupestris but occurs exceptionally 

 in other species as does reduction to one larger megaspore. In 5. 

 Vogelii 12 megaspores were found. In 5. Lyallii the leaf-trace may 

 occasionally split into two bundles. Frequently te leaf-trace is slightly 

 enlarged by the development of secondary tracheides round the 

 base of the ligule. Whether the species are homophyllous or dorsi- 

 ventral, radial symmetry obtains in the cone, except in 5. Lyallii 

 where there are two steles, each with a protoxylem pointing late- 

 rally outwards. It is considered that the function of the ligule is to 

 protect the sporangia from drying up. Isabel Browne (London). 



Sinnott, E. W., Foliar Gaps in the Osmundaceae. (Ann. Bot. 

 p. 107-118. PL 11— 12. January 1910.) 



Mr. Sinnott maintains that as a rule the leaf trace of the 

 Osmundaceae leaves a gap immediately on its departure from the 

 stele, but that in some cases the Cluster of parenchyma after its 

 appearance in the xylem Strand instead of becoming continuous 

 with the pith broke "through the outer part of the xylem first, so 

 that the trace appeared to separate from the original bündle without 

 causing a break in the continuity of the bundly or xylem; but 

 whenever serial sections were cut through such a place the xylem 

 bündle soon became constricted and broken in two by a ray of 

 parenchyma opposite the outgoing trace. This ray soon closing up 

 is regarded as a true foliar gap; this type of delayed gap is found 

 in many though not in most cases in Osmunda and in Todea. 



It is held that the Osmundaceae were primitively phyllosiphonic 

 and that the fossil record is quite compatible with such a view, one 

 that is on the whole confirmed by a study of the ontogeny. It is 

 true that Seward and Ford's work on certain young recent Os- 

 mnndaceae and Kidston and Gwynne Vaughan's on Osmundites 

 Dwilopi is opposed to such a view, but it is suggested that in these 

 cases we may be dealing with delayed gaps such as those described 

 above. As regards the departure of the pinna trace from the leaf 

 bündle there is always a gap developed sooner or later though in 

 some cases it appears at certain levels to be absent. This is held 

 to confirm the view that the departing Osmundaceous trace originally 

 left a gap. Isabel Browne (London). 



Sinnott, E. W., The evolution of the Filicinean leaf- 

 trace. (Ann. Bot. p. 167—191. PI. 11. 11 Textfig. 1911.) 



It is believed that the bases of Fern leaf traces are primitively 

 of three main tvpes; the monarch , the diarch and the triarch. The 

 Fern trace woüld also seem to have been primitively concentric. 

 Centripetal xylem is found in a Fern petiole in Lygodiu m alone 

 among living forms — with the exception of a few Clements in the 



