37 BOTANY i'\KT 11 



consists of a single thin-walled cell, in which tin- whole of the protoplasm. ,i> is 

 tin- rule in all Khodophyceae, is consumed in the formation of <m<- uninuclear 

 si'KK.M.viiJ. M : iii-cordiii^ to sonic authors the nucleus of the spcrmatium divides 

 iuto two. Tin- s|ierniatia an- nearly spherical, and are invested with a thin 

 outer inenihi-iinc or cell wall. They are non-motile, unlike the ciliated sp< T- 

 niatozoids of the other Algne. anil have therefore received a distinctive name. In 

 consequence of their incapacity for independent movement, they must lie carried 

 passively by tlie water to the female organs, which arc situated near the 

 autheridia ;it the ends of other branches. The female organ is called a < AK- 

 POGONIUM (Fig. 313 .#), and consists of an elongated cell with a liasal, llask- 

 sha|ied portion (c) prolonged into a filament, termed the TI:H-HII;YXK (/). Tin- 

 basal portion contains the nucleus of the egg and the chromatophorcs. while tin- 

 trichogyne functions as a receptive organ for the spermatia, one or two of which 

 fuse with it. and the contents, escaping through the .spermathun wall, pass into 

 the nrpogonium. The sjK-rm nucleus juisses 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 tin- carpo- 

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

 product of fertilisation, including the surrounding envelope, constitutes the 

 fructification, and is termed a i YSTIM'AKP. The profusely-branched sporogcnous 

 filaments become swollen at the tips and give rise to spherical, uninuclear s|Mire> 

 known as CAUPOSPOKES, which are eventually set free from the envelop.. In 

 the rase of Batrachospermum the carpos pores 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 tetraspon-s by other Florideae. 



The formation of the cystocarps and carpospmvs j s much more complicated 

 in the case of other genera, but in all eases, according to OI.TMAXXS, the carpooporea 

 are descended from the fertilised egg-cell. There are thus two generations dis- 

 tinguishable in the life-history of the Florideae, the sexual (gametophyte), which 

 bears the egg-cells and the spermatia. and the asexual generation i sporophvte . 

 derived from the fertilised egg-cell ; the latter generation, which produces tin- 

 carposj>ores, remains in connection with the parent plant. This type of alter- 

 nation of generations is comparable with that found in Mosses and Ferns. The 

 production of tetraspores is an asexual mode of reproduction of the sexual genera- 

 tion and precedes the formation of the sexual organs. 



Diulresnaya coccinen, which is found on the warmer 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. 314). 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 u XII.IAKY CKI.I.S. Tin- 

 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 successive fusions with auxiliary cells do not 



