622 SUMMARY OF CUERENT RESEARCHES RELATING TO 



cotyledon, and is distinguislied from all other vascular cryptogams by the 

 absence of a root, its place being supplied by a tuberous swelling, from 

 which proceed a number of root-hairs ; the cotyledon not unfrequently 

 contains no vascular bundle. The stem-bud lies laterally beneath the 

 cotyledon. A non-sexual mode of propagation was observed in the forma- 

 tion of adventitious shoots on leaves when detached from the young plant. 



Anatomy of the Sporangia of Ferns.* — Continuing his previous re- 

 searches on this subject, t Herr J. Schrodt contests the statement of Prantl J 

 that no air penetrates from the outside into the interior of the sporange, 

 so as to cause its rupture. He states that the cells of the annulus of the 

 ripe sporange contain water which evaporates through the thin membrane 

 into the air. In this way the ends of the supports approach, the annulus is 

 stretched, and the sporange ruptured at its thinnest spot. At the moment 

 when the membrane which has become drawn into each cell of the annulus 

 reaches its lowest point, and the surface of the inclosed water cannot sink 

 any lower, a vacuum results, into which air is forced from without ; and 

 since this takes place at the same time in all the cells, the springing apart 

 of the supports to which the spores are attached causes the latter to be 

 violently thrown out. 



Formation of Crystals in the Marattiace8e.§ — According to Herr N. A. 

 Monteverde, the tabular crystals found in the parenchymatous cells of the 

 Marattiacese do not consist, as previously supposed, of calcium and mag- 

 nesium sulphate, but of calcium oxalate. Calcium sulphate does, how- 

 ever, occur dissolved in the cell-sap, and becomes separated in the form of 

 spheerocrystals if the leaves of Angiopteris longifolia or Marattia cicutaefolia 

 are laid for months in alcohol. 



Apogamy in Ferns. |1 — Herr F. F. Stange describes the development 

 of the apogamous prothallium in Todea rivularis, T. pellucida, and Dodea 

 caudata, directly into the young plant. The anterior portion of the pro- 

 thallium thickens into a solid mass of tissue, from the lobes of which the 

 fronds are developed. He also describes the propagation of Mohria thuri- 

 fraga by hibernating prothallia produced directly from tubercles somewhat 

 resembling those of Gymnogramme. 



Apospory in Polystichum angulare var. pulcherrimum "Wills.^ — 

 Mr. C. T. Druery has obtained specimens of Polystichum angulare var. 

 pulcherrimum, in which, as soon as the fronds attained the length 

 of 6 in. or so, the tips of the pinnules began to run out and dilate 

 into prothalli, until the pinnae were absolutely fringed with them. So 

 far, the phenomena observed had been precisely similar to those noticed 

 in Padley's form ; but upon a closer examination, hydraeform bodies 

 attached to the upper surface of the pinnules, and within the margin, 

 were noticed. These were in every case produced at the ends of excurrent 

 veinlets protruding from the surface of the pinnules, and thickening at 

 the distance of about 1/20 in. into a pear-shaped body, from which 

 radiated in all directions numerous root-like hairs. Gradually this grew 

 into an undoubted prothallus, though much thicker in substance than those 

 produced by extension of the pinnule tips. From these observations it 



* Flora, Ixx. (1887) pp. 177-92, 202-8. 



t See this Journal, 1886, p. 828. J Ibid., 1886, p. 1020. 



§ Arbeit. St. Petersburg. Naturf. Gesell., xvii. (1886) pp. 33-4. See Bot. Centralbl., 

 xxix. (1887) p. 358. 



II SB. Gesell. Bot. Hamburg, March 25, 1886. See Bot. Centralbl., xxix. (1887) 

 p. 351. 



^ Journ. Linn. See. Lond., xxii. (1887) pp. 437-40 (3 fig^.). 



