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these plants, it will be useful to give rather a detailed account of their 

 stmcture, in which 1 avail myself chiefly of Ad. Brongniart's remarks in the 

 place above referred to, and of Agardh's observations in the Jinn, des Sciences, 

 4. 61. I have not seen Professor Nees v. Esenbeck's monograph of Characeee 

 in the Transactions of the Ralisbon Society, quoted by the latter author. 



Characeee are aquatic plants, found in stagnant fresh or salt water ; always 

 submersed, giving out a fetid odour, and having a dull greenish color. Their 

 sterns are regularly branched, brittle, and surrounded here and there by whorls 

 of smaller branches. In Nitella the stem consists of a single transparent tube 

 with transverse partitions, and, as Agardh remarks, so like the tubes of some 

 Algae, as to offer a strong proof of the affinity of the orders. In Chara, proper- 

 ly so called, there are, in addition to this tube, many other external ones, much 

 smaller, which only cease to cover the central tube towards the extremities. In 

 the axillae of the uppermost whorls of these branchlets the organs of repro- 

 duction take their origin ; they are of two kinds, one called the nucule, the 

 other the globule ; the former has been supposed to be the pistillum, the latter 

 the anther. 



The nucule is described by Dr. Greville as being " sessile, oval, solitary, 

 spirally striated, having a membranous covering, and the summit indistinctly 

 cleft into 5 segments ; the interior is filled with with minute sporules." Fl. 

 Edin. xvii. This is the general opinion entertained of its structure. But Ad. 

 Brongniart describes it thus . — " Capsule unilocular, monospermous ; pericarp 

 composed of two envelopes ; the outer membranous, transparent, very thin, 

 terminated at the upper end by 5 spreading teeth ; the inner hard, dry, opaque, 

 formed of 5 narrow valves, twisted spirally ." Diet. Class. 1. c, He founds 

 his opinion of the nucule containing but one germinating body upon the experi- 

 ments of M. Vaucher, of GJeneva, who ascertained that if ripe nucules of Chara, 

 which have fallen naturally in the autumn, are kept through the winter in 

 water, they will germinate about the end of April; at that time a little body 

 protrudes from the upper end between the £ valves, and gradually gives birth 

 to one whorl of branches, which produce a second. Below these whorls the 

 stem swells, and little tufts of roots are emitted. The nucule adheres for a 

 long time to the base of the stem, even when the fatter has itself begun to 

 fructify. Hence it is reasonable to conclude that the nucule is really mono- 

 spermous. M. Brongniart remarks, that it is true, when a fresh nucule of 

 Chara is cut across, an infinite number of little white grains are squeezed out ; 

 but if these were really all reproductive particles, how would they ever find 

 their way out of the nucule, which is indehiscent? He considers them rather of 

 the nature of albumen ; and he is the more confirmed in his opinion, because 

 in Pilularia, the thecae of which also contain many similar grains, but one plant 

 is produced by each theca. Finally, Amici has described (Ann. des Sc. 2.) 

 the "nucule in another way. He admits it to be monospermous, but he considers 

 the points of the 5 valves to be stigmata, and the valves themselves to be at 

 once pericarp and style. It is not worth entering into any discussion upon the 

 reasonableness of such a supposition, as it is not likely to find any advocates 

 among botanists ; but I may observe, that Arnici's observations seem to show 

 that the 5 valves of the nucule, as they are called, are a verticillus of leaves, 

 straight at first, and twisted afterwards ; and that the nucule itself is, therefore, 

 analogous to the bud of flowering plants. 



The globule is described by Dr. Greville as " a minute round body, of a reddish 

 colour, composed externally of a number of triangular (always?) scales, which 

 separate and produce its dehiscence. The interior is filled with a mass of elas- 

 tic transversely undulate filaments. The scales are composed of radiating hol- 

 low tubes, partly filled with minute coloured spherical granules, which freely 

 escape from the tubes when injured," Vaucher describes them as " tubercles 



