534 SUMMARY OF CURRENT RESEARCHES RELATING TO 



itself, while the lower wall is a lamella of tissue springing from the 

 outer part of a vein. The sporangium springs, as in Anemia, from the 

 margin of the leaf, while behind the sporangium is formed an annular 

 wall, the indusium, which encloses the sporangium like a hood, the 

 sporangium becoming eventually placed, in the course of develop- 

 ment, on the under side of the leaf. Such a sporangium, covered by 

 an indusium, is termed by the author a " monangic " sorus. 



The apex of the young leaves is occupied by a wedge-shaped 

 apical cell. In the finer veins the structure of the vascular bundles 

 is collateral. No spiral vessels occur in the stem, and the sieve-tubes 

 are very small. The mesophyll does not possess any true palisade- 

 parenchyma, and is very nearly alike on the two sides of the leaf. The 

 epidermis is not sharply separated from the fundamental tissue. In 

 Anemia and Schizwa the cuticle is provided with siliceous warts. In 

 Anemia elegans the stomata occur only on the upper side of the leaf. 

 Those of Schizaia are arranged in two longitudinal rows on each side 

 of the veins. 



As regards classification, Prantl divides the Filices into three 

 primary groups, viz. (1) Hymenophyllacese, Polypodiaceae, and Cya- 

 theaceaa ; (2) Schizseacese, GleicheniaceEe, and Parkeriaceas ; and (3) 

 Osmundacese, Opkioglossacess, and Marattiaceae. Ceratopteris he 

 treats as belonging to the Schizaaaceae ; it has monangic sori, as also 

 has Botrycliium. The author regards the Schizseaceae as presenting 

 the closest affinity among ferns to flowering plants. He inclines to 

 the view that the nucellus of the ovule is homologous to the sporan- 

 gium, and the entire ovule to a monangic sorus with its indusium. 



Muscinese. 



Branched Sporogonium of a Moss.* — C. Fehlner describes an 

 instance of branched sporogonium in Meesea uliginosa. From a 

 common seta spring two sporangia, each with normal operculum and 

 peristome. The capsule of Meesea not being regular, but laterally 

 symmetrical owing to a curvature, the two sporangia are placed back 

 to back in the same plane of symmetry, and the mutual pressure 

 causes the surfaces which are in contact with one another to be some- 

 what flattened. 



Leitgeb regards this and similar recorded cases of branched sjjoro- 

 gonium as indicating reversion towards earlier forms of Archegoniataa 

 in which the sporogenous generation is normally branched. He states 

 that they do not result from the archegonium containing two oospheres, 

 or from coalescence of two embryos, but from vertical segmentation of 

 the apical cell of the embryo, which therefore branches when it has 

 attained a certain stage of development. 



Influence of Light on the Thallus of Marchantia.j — A. Zim- 

 mermann contests Pfeffer's statement that the development of root- 

 hairs from the gemmae of Marchantia is determined only by contact 

 with the surface of the soil ; he finds, on the contrary, that in addition 



* Oesterr. Bot. Zeitschr., xxxii. (1882) p. 185. 



t Arbeit. Bot. last. Wiirzburg, ii. (1882) pp. 665-9. 



