340 DEVELOPMENT AND REPRODUCTION OF CHARACECE. 



to be formed by the aggregation of the smaller particles.* The 

 production of new Cells for the extension of the stem or branches, 

 or for the origination of new whorls, is not here accomplished by 

 the subdivision of the parent-cell, but takes place by the method 

 of out-growth (Fig. 158, b, e, f, g, h), which, as already shown 

 (§ 249), is nothing but a modification of the usual process of cell- 

 multiplication ; in this manner, the extension of the individual 

 plant is effected with considerable rapidity. "When these plants are 

 well supplied with nutriment, and are actively vegetating under 

 the influence of light, warmth, &c. , they not unf requently develope 

 'bulbels,' or Gonidia of a peculiar hind, which serve the same 

 purpose in multiplying the individual, as is answered by the Zoo- 

 spores of the simpler Protophytes : these are little clusters of cells, 

 filled with starch, which sprout from the sides of the central axis, 

 and then, falling off, evolve the long tubiform cells characteristic 

 of the plant from which they were produced, t The Characece may 

 also be multiplied by artificial subdivision; the separated parts 

 continuing to grow under favourable circumstances, and develop- 

 ing themselves into the typical form. 



255. The Generative apparatus of Characece consists of two 

 sets of bodies, both of which grow at the bases of the branches 

 {Fig. 159, A, b); one set is known by the designation of ' Globules,' 

 the other byfthat of ' Nucules.' The former are really Antheridia, 

 whilst the latter contain the Germ-cells. The 'Globules,' which 

 are nearly spherical, have an envelope made up of eight triangular 

 valves (b, c), often curiously marked, which encloses a nucleus of 

 a light reddish colour : this nucleus is principally composed of a 

 mass of filaments rolled up compactly together ; and each of these 

 filaments (c) consists, like a Conferva, of a linear succession of 

 cells. In every one of these cells there is formed, by a gradual 

 change in its contents (the successive stages of which are seen at 

 D, e, f), a spiral thread of two or three coils, which, at first motion- 

 less, after a time begins to move and revolve within the cell ; and 

 at last the cell-wall gives way, and the spiral thread makes its 

 way out (g), partially straightens itself, and moves actively through 

 the water for some time (h) in a tolerably determinate direction, 

 by the lashing action of two long and very delicate filaments with 

 which they are furnished. The exterior of the ' Nucule ' (a, b) is 

 formed by five spirally-twisted tubes, that give it a very peculiar 



* This interesting phenomenon may he readily observed, by taking a 

 small portion of the Plant out of the water in which it is growing, and 

 either placing it in a large Aquatic Box (§ 97) or in tbe Zoophyte-Trough 

 (§ 98), or laying it on the glass Stage-plate (§ 96) and covering it with 

 thin glass. The modification of the stage-plate termed the ' Growing 

 Slide ' (§ 96) will enable the Microscopist to keep a portion of Chara under 

 observation for many days together. 



t This multiplication by bulbels was described by Amici in 1827 ; but 

 his observations seem to have been forgotten by Botanists, until the re- 

 discovery of the fact by M. Montagne. 



