192 SUMMAKY OF CUKRENT RESEARCHES RELATING TO 



Hypnacege were forthcoming. This station is now nearly destroyed by 

 building, etfc. After a close study of Drepanodadus, the author finds 

 himself in sympathy with Renauld as to the main treatment of the group. 

 He gives details as to the grouping of the forms, though the number of 

 intermediates is so vast that they tend to link all the forms into one big 

 species. In concluding his paper, the author adds a list of 38 species of 

 historic interest, first recorded from Saxony by Schreber or Hedwig ; 

 20 of these were collected close to Leipzig. 



Monograph of Lophocolea.* — F. Stephani gives descriptions of 27 

 species of Lophocolea, eight of which are new to science. All the species 

 described were collected in Central or South America. 



Nematode Galls on Liverworts.t — C. Warnstorf records the first 

 occurrence of Nematode galls observed by him on an hepatic. They 

 formed dark-green spherical heads on the apex of stems of Cephalozia 

 connivens f . Inxa. They are composed of densely-crowded, superposed, 

 lobed, ciliated, degenerate leaves, and contained one or two Anguillula- 

 worms. Whether they are the same as those occurring in moss-galls is 

 at present unknown. 



Contractile Tissues of Mosses.J^W. Lorch has investigated the 

 movements and shrivelling of the stems and leaves of several mosses 

 caused by a loss of water. These phenomena occur in a marked degree 

 in Leptodon, a genus of Xeckeracea3. The author has specially studied 

 these movements in L. SmithU, and found in the creeping primary stem 

 and in its ascending branches a band of thick-walled cells on the dorsal 

 side which contract when dried and produce the movements and coiling. 

 In the leaves of Gatharima Haitsknechtiihe found that the cells on each 

 side of the costa exert a contractile force and render the lamina 

 undulate. It is presumably the cell-walls and not the cell-contents that 

 effect the contraction. He examined Dawsonia superha and other 

 Polytrichefe of the type of Polytric}i um piliferum, and found in all those 

 which possess a distinct leaf-sheath a well-marked contractile tissue which 

 probably belongs rather to the lamina than to the sheath. 



Stem Leaves of Sphagnum.§ — W. Lorch discusses the mechanical 

 system of the stem-leaves of Sphagnum, which he holds to be as highly 

 developed as the branch-leaves, despite the opinion of Russow. He 

 considers the development of the strengthening ribs and the pores of 

 the hyaline cells of the leaf and their relation to one another. The 

 membranes of the chlorophyll-cells serve to stiffen the leaf. The stiffen- 

 ing apparatus is more highly developed in the upper than in the basal 

 hyaline cells of the leaf. The difference in shape of the upper hyahne 

 cells as compared with the lower is explained on biological grounds. It 

 is of great importance that the terminal bud should be protected from 

 drying up ; and it is closely covered with imbricating stem-leaves, the 

 upper outer sides of which are exposed to incident water, for the 

 capillary absorption of which, by means of minute pores, the upper 



* Bull. Herb. Boissier, vii. (1907) pp. 59-72. 



t Allg. Bot. Zeitschr., xii. (1906) p. 194 (figs.). 



t llora, xcvii. (1907) pp. 76-95 (figs.). § Tom. cit., pp. 96-106 (figs.). 



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