SECT. I CRYPTOGAMS 377 



for independeut movement, they must be carried passively by the water to 

 the female organs, whicli are situated near the antheridia at the ends of 

 other branches. The female organ is called a caiipogoxium (Fig. 303, B), . 

 and consists of an elongated cell with a basal, Hask- shaped portion (c) pro- 

 longed into a filament, termed the tkichogyxe [t). Tlie basal portion contains 

 the nucleus of the egg and tlie chromatophores, while the trichogyne functions 

 as a receptive organ for the spermatia, one or two of which fuse with it, 

 and tlie contents, escaping through the sperraatium wall, pass into the carpo- 

 gonium. The sperm nucleus passes down the trichogyne and fuses with the 

 nucleus of the egg-cell. The fertilised egg, which becomes limited from the 

 trichogyne by a wall, does not become converted directly into an oospore, but, 

 as a result of fertilisation, numerous branching sporogenous filaments grow- 

 out from the sides of the ventral portion of the carpogonium. At the same 

 time, by the development of outgrowths from cells at the base of the carpo- 

 gonium an envelope is formed about the sporogenous filaments. The whole 

 product of fertilisation, including the surrounding envelope, constitutes the 

 fructification, and is termed a cystocarp. The profusely-branched sporogenous 

 filaments become swollen at the tips and give rise to spherical, uninucleate spores 

 known as caepospores, which are eventually set free from the envelope. In 

 the case of Batraehospermum the carpospores produce a filamentous protonema, 

 the terminal cells of which give rise to asexual unicellular spores. These spores 

 serve only for the multiplication of the protonema. Ultimately, however, one 

 of the lateral branches of the protonema develops into the sexually differentiated 

 filamentous thallus. The production of spores by the protonema is analogous to 

 the formation of tetraspores by other Florideae. 



The formation of the antheridia (■''^) as well as the frequently complicated 

 cystocarps and carpospores* exhibits various types in the Florideae, but in all 

 cases, according to Oltmanns, the carpospores are descended from the fertilised 

 egg-cell. There are thus two generations distinguishable in the life-history of 

 the Florideae, the sexual (gametophyte), which bears the egg -cells and the 

 spermatia, and the asexual generation (sporophyte), derived from the fertilised 

 egg- cell; the latter generation, which produces the carpospores, remains in 

 connection with the parent plant. This type of alternation of generations is 

 comparable with that found in Mosses and Ferns. The production of tetraspores 

 is an asexual mode of reproduction of the sexual generation and precedes the 

 formation of the sexual organs. 



Dudrcsnaya coccinca, which is found on the wanner coasts of Europe, has a 

 branched, cylindrical thallus and will serve as an example of the more complicated 

 mode of origin of the spore -bearing generation (Fig. 304). The carpogonial 

 branches consist of about seven cells, the terminal one bearing a very long 

 trichogyne. After fertilisation the carpogonial cell grows out into a filament, 

 which elongates and becomes branched. This filament fuses with a number of 

 special cells, characterised by their abundant contents, the auxiliary cells. The 

 first of these lie in the carpogonial branch itself, the others in adjoining lateral 

 branches. All the nuclei of the sporogenous filament are derived by division from 

 that of the fertilised egg-cell. The siiccessive fusions with auxiliary cells do not 

 involve nuclear fusions, but simply serve to nourish the sporogenous filament. A 

 second and third sporogenous filament may arise from the carpogonial cell. Two out- 

 growths now arise from each of the swollen cells of the sporogenous filament 

 which fused with auxiliary cells. By further division of these outgrowths the sjiherical 

 masses of carpospores, which subsequently become free, are derived (Fig. 304, E). 



