194 Pteridophyten. 



sporangium was prevented by excessive dampness. Thougli darkness 

 retards and eventually arrests growth, and though prothalli grown 

 in the dark often have abortive antheridia, the latter may develop 

 in the absence of light. The reason suggested for the precocious 

 development of antheridia by prothalli enclosed in the sporangia is 

 that the mechanical hinderances to the growth of prothalli caused by 

 the sporangial wall results in concentration of certain organic food 

 substances leading to special nutrition of the protoplasm. The anthe- 

 ridia are usually absent from the first formed prothalli, perhaps 

 because this pressure is still insufficient. Severe scarcity of water 

 might have the same result, hindering growth without checking the 

 accumilation of certain food-substances. Isabel Browne (London). 



BoAver, F. O., Note on Ophioglossum simplex, Ridley. (Ann. 

 Bot. p. 327—328. 1908.) 



This species, when described by the author in V'ol. XVIII. of 

 the Annais of Botany, appeared to differ frum other Ophiogiossaceae 

 in the absence of a sterile lamina. It was placed by him in the 

 § Ophioderma and was regarded as the extreme term of a reduction 

 series — a view opposed by Campbell who regarded it as the 

 most primitive known species of the genus. Tn certain new speci- 

 mens of 0. simplex from a dense forest in Sumatra a very small 

 sterile lamina is present below the fertile region. These fresh facts 

 are held to support the author's theory that 0. simplex is reduced 

 and not primitive. Isabel Browne (London). 



Gwynne-Vaughan, D. T., On the Real Nature of the 

 Tracheae in Ferns. (Ann. Bot. p. 517—523, with 1 plate. 1908.) 



The Osmundaceae frequently possess two or more series of pits 

 on the walls of their woody elements. In both recent and fossil 

 forms the elements hitherto described as tracheides are in reality 

 tracheae, for not only are the pits on their walls devoid of a closing 

 membrane, thus forming perforations leading from one trachea to 

 another, but eventually the whole of the primary wall is reabsorbed 

 (except at the angle of the vessel) so that at maturity there is an 

 empty space between the two opposite bars of thickening of adja- 

 cent tracheae. When the wall bears more than one row of pits the 

 portions of the primary wall separating the series vertically persist. 

 The primary wall is also completely reabsorbed in the typically 

 scalariform vessels of Nephrodium Filix-Mas. In the Polypodiaceae , 

 Hymenophyllaceae, Gleicheniaceae , Schisaeaceae , Marattiaceae, Ophio- 

 giossaceae, Lycopodiaceae and in the fossils Psaronius, Botvyoptevis 

 and Zygopteris the pits of the wood}»^ elements proved to be true 

 perforations, so thät these also are tracheae, though in them the 

 primary wall is not reabsorbed True (indisputably imperforate) tra- 

 cheides were not met with among the Pteridophyta examined, but 

 these were too few to generalize from. True tracheides probably 

 occur in the Calamariae. Isabel Browns (London). 



Hicken, C. M., Heiechos nuevos para la Argentina. (Apun- 

 tes de Historia Natural. I. p. 37. Buenos Aires. 1909.) 



Especes non signalees pour l'Argentine, trouvees aux envi- 

 rons du lac Nalmel-Huapi: Nephrodium subincisum (Willd.) 



