426 INTRODUCTION TO CETPTOGAMIC BOTANY. 



from the centre of each of which a centripetal column springs 

 perpendicularly, bearing towards the apex articulated threads, 

 the articulations of which produce a spiral spermatozoid. 



ChaeacEjE, Rich., Brongn. Chares, Kiltz. 



469. This is a small order consisting of but three genera. 

 All the species are aquatic, and imable to endure much expo- 

 sure to the atmosphere. They are more or less diffused over 

 the whole world, being as abundant in some parts of the 

 southern hemisphere as in the northern.* The nucules of 

 Characew occur in the lower fresh-water formation, and in 

 succeeding strata, and are known under the name of Gyrogo- 

 nites. They have attracted more attention than such obscure 

 plants might otherwise have done, from the curious structure 

 of their antheridia, and the clearness with which the cir- 

 culation is seen, in one at least of the genera, under the 

 microscope. 



470. Nitella differs from Chara, in having very nearly the 

 structure of a Cladophora, consisting, that is, of threads formed 

 of joints, placed end to end, and more or less branched. These 

 distiactions are not, however, absolute. Charopsis, Ruprecht, 

 contains those uncoated monoecious species in which the an- 

 theridium takes the place of one of the bractes, and the nucule 

 is seated directly above it ; in other words, the nucule is 

 axillary. In Lychnothamnus, Ruprecht, the species are also 

 moncecious, and the antheridium is placed by the side of the 

 nucule. Charopsis, Kiitz., includes both genera. In Cha- 

 racecB, however, all the divisions are more or less perfectly 

 disposed in whorls. There is a creeping root which some- 

 times produces nodular reproductive bodies, rich in starch 

 grains'; and besides these amorphous masses, stellate bodies 

 occur in. Chara steUigera,^ which arise from a modifi- 

 cation of the nodes, composed of cells filled with starch grains. 



* See Braun in Hook. Journ. 1849, p. 193. One species only is 

 noticed in the Flora of New Zealand, but several others occurred, which 

 could not be described in consequence of defective materials. The 

 Australian species are mostly Nitdla. 



t Montague, Ann. d. Sc. Nat., ser. 3, vol. xviii., p. 65. 



