82 FLORIDEJE. 



cells. These are either dispersed in the interior of the thallus, 

 or are arranged together in pairs with the cell-filament which 

 bears the carpogonium, and are generally united with this to 

 form an independent multicellular procarpium. The spermatia 

 attach themselves firmly to the trichogyne and surround them- 

 selves with a cell- wall. The dividing wall at the point of contact 

 is perforated, and the nucleus of the spermatium probably travels 

 through the trichogyne to the swollen part of the procarpium 

 the carpogonium and fuses with its nucleus. After fertilisation 

 the trichogyne withers (Fig. 77 0), bat the lower portion of the 

 procarpium, constituting the fertilised oosphere, grows out and 

 forms in various ways, first a tuft of spore-forming filaments 

 known as gonimoUasts, and finally the carpospores. These latter 

 form a new asexual generation (compare the germination of th& 

 oospore of CEdogonium and Coleochcete}. 



The gonimoblasts may arise in three ways : 



1. In the Nemalionales, branched filaments grow out from the oosphere and 

 form an upright, compressed or expanded tuft of spore-forming filaments. 



2. In the Cryptonemiales, several branched or unbranched filaments (ooblas- 

 tema-filaments) grow out from the oosphere, and conjugate in various ways with 

 the auxiliary cells. The gonimoblasts are then formed from the single cells 

 produced by the conjugation. 



3. In the Gigartinaies and Rhodymeniales the oosphere conjugates with an 

 auxiliary cell by means of a short ooblastem a- filament, and from this auxiliary 

 cell a gonimoblast is produced. 



The motionless carpospores, which sometimes in the early stages are naked, 

 and afterwards invested with a cell-wall, are developed from the terminal cells 

 (and perhaps also from some of the other cells) of the branches of the gonimo- 

 blast. The gonimoblasts constitute sharply defined parts of the plant in which 

 the carpospores arise. These parts are called cystocarps and are either naked 

 (Fig. 77 -E), or surrounded by a covering (pericarp or involucre, Fig. 77 A^ 

 formed in different ways. On this account the Florideae were formerly divided 

 into GTYMNOSPORE^E (Batrachospcrmum, Nemalion, Ceramium, etc.) and ANGIO- 

 SPORE.E (Furcellaria, Lejolisia, Delesseria, Melobesia, etc.). 



The Floridea3 are divided into four sub-families : 



Sub-Family I. Nemalionales. The fertilised oosphere produces directly 

 the gonimoblast. 



Order 1. Lemaneaceae. Algse of brownish colour and living in fresh 

 water. They lack tetraspores, and the very sparingly branched fertile filaments, 

 composed of many rows of cells, grow out from a pro-embryo, which consists of 

 a single row of cells bearing branches. Lemanea fluviatilis, often found OB 

 rocks and stones in quickly flowing streams. 



