380 



BOTANY. 



The steins are developed from a triangular apical cell, while the 

 roots, like those of Marattiacece, possess no apical cell,' but a group 

 of cells instead. The fibro-vascular bundles are arranged in a cylinder 

 {a circle in cross-section), and they form a network by their anastomos- 

 ing with each other. According to De Bary, they belong to the "col- 

 lateral " series. 



These plants are usually of small size, rarely exceeding 30 centime- 



Fig. 271. — A, vertical section of an archegoninm and the rudimentary prothallium 

 of Pilvlnria globulifera { w, w, part of the ruptured wall of the macrospore ; p, p, 

 the rudimentary prothallium, merging above into the archegoninm ; g, the germ-cell 

 ready for fertilization ; ac, the cavity of the macrospore. X 500. 5, a microspore 

 of the same burst open and allowing the escape of sperm-cells, s, from which sper- 

 matozoids arc escaping, x 600. C, longitudinal section of a macrospore of ScUvinia 

 natans at the commencement of germination ; p, the young pi-othallium. x 30. i>, 

 a very young prothallium of the same, detached, with a fragment of the inner spore- 

 membrane (m) adhering to it— top view, x 200. B, a vertical longitudinal section of 

 D. X 200. P a similar section of a more advanced prothallium of the same ; g. the 

 young germ-cell, x 200. (?, vertical section of an unfertilized archegoninm of the 

 same, surrounded by cells of the prothallium ; gr, germ-cell ; ar, canal of the arche- 

 gonium. x 300.— After Hofmeister. 



tres (1 foot) in height ; in one Ceylonese species {OpMoglossum pendu- 

 I'lm) the slender pendent leaves are sometimes, according to Hooker, 

 nearly three metres long (15 feet). 



There are three genera, viz., OpMoglossum, Botrychium, and Helmin- 

 tlbostaehys ; the latter is confined to the southern hemisphere, the others 



G. E. Davenport's paper. Vernation in Botrychia, in the Bulletin of 

 the Torrey Botanical Club, 1878 ; it is illustrated by figures. 



