ZOOLOaY AND BOTANY, MICROSCOPY, ETC. 277 



2, Bidentata ; 3, Inasquilatera ; 4, Connata ; 5, Vittata ; 6, Parvistipula ; 

 7, Serrulata ; 8, Appendiculata ; 9, Fissistipula ; 10, Cordistipula ; and 

 11, Grandistipula. 



Rabenhorst's ' Cryptogamic Flora of Germany ' (Musci). — In parts 4-6 

 of this work Herr K. G. Limpricht completes the Cleistocarpae, a new genus 

 Aschisma being founded on Phascum carniolicum. The second division of 

 the Bryineae, viz. the Stegocarpse, is then commenced, the first section of it 

 only, the Acrocarpse, being at present reached. This section he divides 

 into thirty-eight families, an analytical key of which is given. In the 

 family Weissiacese, a new genus Molendoa is also formed out of Anoectangium 

 Hornschuchianum and Sendtneriamim, a new species M. tenuinervis being 

 also described. The illustrations are numerous and excellent. 



CharaceaB. 



Rotation in Nitella.* — Mr. W. Whiteleggge describes a species of 

 Nitella found in the Paramatta Eiver, Australia, in which some of the inter- 

 nodal cells measured from 7 to 8^^ in. in length, probably larger than those 

 of any hitherto recorded. The rotation exhibited in the inner nodal cells 

 differs from that of the stems and leaves, inasmuch as the chlorophyll- 

 granules take part in the general rotation. The protoplasm in the young 

 leaves, when viewed under the Microscope with the edge of the cell in 

 focus, appears as a series of elevations and depressions ; and with the higher 

 part of the cell in focus these elevations appear as clear spaces surrounded 

 by small granules. Within the layer of protoplasm there exist large 

 numbers of spherical clusters of needle-like crystals, which circulate along 

 the line of demarcation between the cell-sap and the protoplasm. 



Algae. 



Formation of Cysts in the Chlorosporese.f — M. F. Gay proposes the 

 general term cyst for all cells of non-sexual origin in the green algm which 

 reproduce the plant by remaining dormant for a period and then germi- 

 nating (Dauersporen, Euhesporen, spores durables, spores dormantes, rest- 

 ing-spores, hypnospores, chronospores, aplanospores, akinetes, of various 

 authors). They may be formed in two ways, exogenously by the thickening 

 of the cell-wall and gelification of its outer layers, or endogenously by the 

 contraction of the protoplasmic contents, which then surrounds itself with 

 a new membrane of its own. 



In the Conjugatse the formation of fcysts has been observed, especially 

 in species of Zygnema growing in dry situations ; the filaments break up 

 into fragments and become inclosed in a mucilaginous sheath produced by 

 the gelifying of the outer layers of the cell-wall. Cysts formed under these 

 conditions may preserve their vitality for months. When moisture again 

 penetrates the sheath the dormant cells divide by septa and develope into 

 new filaments. 



In the ProtococcoidesB M. Gay has observed the formation of exogenous 

 cysts in a species of Tetraspora and in one of Chlamydomonas. In T. gela- 

 tinosa they result from the encysting of zoospores. A similar process takes 

 place in tjlothrix tenerrima and in Microspora tenerrima, with the exception 

 that, in the latter case, no gelification was observed of the outer layers of 

 the cell-wall. 



In Stigeoclonium the cysts are formed by the contraction of the contents 

 of the mother-cell, which then divide into two or four spores, or, in the 



* Proc. Linn. Soc. N. S. Wales, i. (1886) p. 476. 



t Bull. Soc. Bot. France, viii. (1886) Sess. Estraord., pp. li.-lx. 



