174 ENGLISH BOTANY. 



coated with five cells coiled spirally round it, terminated by a coronula, 

 or crown, of 5 prominent cells in 1 row, or of 10 less prominent ones 

 in two superposed rows. The apical cell of the nucleus is fertilised 

 by the antherozoids ; ultimately the nucule falls and germinates, 

 [producing two shoots, one of which descends into the soil, produces 

 root-hairs, and remains colourless, constituting the primary rhizoid; 

 the other shoot ascends, and soon develops chlorophyll ; its longi- 

 tudinal growth is limited to a few cells, but at about its middle or 

 below, a bud is formed, from which the perfect plant is developed : 

 sometimes two or more rhizoids, and two chlorophyll-bearing shoots 

 are produced from the same nucule. See Plate 1905, and A. de Bary 

 in ' Botanische Zeitung,' 1875, p. 377, t. v. and vi.] * 



GENUS I.— N I T E L L A. Agardh. 



Internodes of the stem more or less pellucid, naked, without a 

 covering of parallel cortical cells, also without a whorl of stipule-cells 

 below the whorl of branchlets. Nucule with a crown of 10 small 

 erect cells in 2 superposed rows, the cells of the upper row much 

 smaller than those of the lower row, generally falling off before the 

 nucule is ripe. 



Section I.— EU-NITELLA. A. Braun. 



Globules in the forks of the branchlets, of which the terminal 

 rays are either 1-celled, or, if of more than 1 cell, having the apical 

 cell much smaller than that behind it. Nucules below the globules. 



SPECIES I.— N ITELLA FLEXILIS. Agardh. 



Plate 1899. 



Braun, Babenhorst, and Stizinger, Char. Europ. Exsicc. Nos. 22, 23, 24, 54, 55, 101. 



Nordstedt and Wahlstedt, Char. Scand. Exsicc. Nos. 8-14. 



NiteUa flexilis, Agardh, Syst. Alg. p. 124. Groves in Journ. Bot. 1880, p. 166, t. 210, 



* Owing to the indisposition of Mr. Boswell, the task of bringing the Ckaracese 

 down to date, and seeing this portion of English Botany through the press, has been 

 entrusted by the publishers to myself; and in order that it may be known what 

 portions I am responsible for, everything that I have added to Mr. Boswell's work is 

 included in square brackets thus [ ], with the exception of the bulk of the synonymy 

 for which I am chiefly responsible, some additional localities, and a few words it has 

 been necessary to add or alter here and there in order to make the context clearer ; 

 beyond this, the work stands just as Mr. Boswell left it. — N. E. Brown, Herbarium, 

 Kew, Surrey. 



