404 SUMMARY OF CUKRENT RESEARCHES RELATING TO 



the fern does not occur in the Prussian territory on the Luxemburg 

 frontier, which is close to its habitats ; tlie artificial introduction of it 

 failed here. The plant has a rich spore production and flourishes only 

 on porous sandstone (not on the sandy debris from it). The patches 

 are orientated only between S.E. and S.W., most frequently S.E. A 

 diagram shows the frequency of the individuals. The dry N.E. and E. 

 wiuds are kept off the delicate plant by the walls of the " schliiff " : 

 where such a wind reaches it, the plant dries up. Presumably it spread 

 along the Atlantic coast to Luxemburg during the time when Great 

 Britain was connected with the Continent. E. S. G. 



Keys to the Ferns of Borneo. — Edwin Bingham Copeland 

 (Sarmvak Museum Journal, 1917, 2, 287-424). An enumeration of 

 the fern flora of Borneo, with the distribution of the species and some 

 critical remarks, and with ample keys for the determination of the 

 families, genera and species. Of the Malay Islands Borneo is the 

 richest in ferns, and yet very few localities in it have been properly 

 investigated. It is to stimulate further research that the author 

 compiled these helpful keys. The number of species already known is 

 about 700 : and it is hoped, from experience gained in the Philippine 

 Islands, that 40 p.c. more may be found. In the introduction the 

 question of a natural classification is discussed. A. G. 



Bryophyta. 



Dissymmetry of Structure of the Leaf of Mnium spinosum. — 

 J. PoTTiER {Berne : Buckler & Co., 1917, 16 pp. 8vo, 7 pis. ; see also 

 Bot. Centralbl., 1918, 138, 353). The material examined was collected 

 at Kandersteg in the Bernese Oberland. Two leaves of different size of 

 the male plant were studied in great detail, 340 transverse sections being 

 made of one leaf and 230 of the other. Every section was drawn, and 

 25 were figured. The asymmetry was observed to vary 3-4 times 

 from right to left, and vice versa, in the same leaf, the change being- 

 more marked towards the apex than in the lower portion of the leaf. 

 The asymmetry corresponds with the sinuations of the costa, so that a 

 curve of the costa to the left corresponds with a left-sided asymmetry. 

 The cause of the asymmetry of the midrib is to be sought in the 

 sinuous character of the costa, which is always more marked towards 

 the apex. The cause of the sinuosity of the costa is to be sought in 

 the growth of the two-sided apical cell of the leaf. The greater the 

 intercalary growth, the weaker is the undulation of the midrib, and the 

 less marked is the asymmetry of the costa. E. S. Gepp. 



Bryum veronense De Not. — C. Massalongo {Bull. Soc Bot. Itah, 

 1917, 33-36, figs.). A discussion of the specific rank of Bryum 

 veronense discovered by the river bank near Verona in 1834 by De 

 Rainer and described by De Notaris as a new species related to B. calo- 

 phyllum. It is a rare moss, known only in a vegetative state, and its 

 systematic position has been a puzzle to subsequent bryologists, as is 

 shown by the synonymy. It has been recorded also for Bavaria and 

 Styria ; and recently it was found again in its original locality. It is 



