EMBETOGENT IN ALG^E. 273 



and xcx.g'jrog, fruit), which is sometimes supported on a cellular body- 

 called trichophore {6§i^, t-j'%05, hair, 

 pojEw, I bear). In some cases, as in 

 Nemalion, the fertilisation is direct, 

 the influence of the antheridian cor- 

 puscle being at once conveyed by 

 the trichogynium to the rudiment- 

 ary cell of the cystocarp. In other 

 cases, as in Dudresnaya, the action 

 is less direct — the influence of the 

 antheridian corpuscles being con- 

 veyed by connecting tubes which 

 pass laterally from the base of the 

 trichogynium to numerous fructi- 

 ferous filaments, on which the 

 cystocarps are iinally developed. 



In Floridese there are also bodies 

 called tetraspores (^rer^dg, four), on 

 account of their being divided into 

 four spore-like organs. These are contained in a distinct sac (fig. 

 482). They are probably concerned in vegetative and not in sexual 

 reproduction. In the brown seaweeds (Fucacese) there are concep- 



6 

 Fig. 481. 





Fig. 482. 



Pig. 483. 



Fig. 484 a. Fig. 484 6. Fig. 485. 



tacles (fig. 483) containing antheridia (%. 484, a and 6) and archegonia 

 (^g. 485), either separate or combined, the plants thus \}emg monoecious 

 or dioecious. 



Fig. 481. Saprolegnia sliowing organs of reproduction, act, Filaments containing aaeXual 

 zoospores, some of which are being emitted from the end of the cell. 1), Stalked sporangium 

 (oosporangium) ending in a rounded cell c, containing in its interior cells called oogones 

 ready to be fertilised, d, Antheridium coming into contact with the female cell, and sending 

 tubes to the oogonia so as to fecundate them. Fig. 4S2. Tetraspore, i, of one of the rose- 

 coloured Seaweeds (Callithamnion cruciatim). It is a sac formed by the metamorphosis of 

 the lowermost pinnule of the frond, and contains four germinating spores. Fig. 483. Cell 

 of a conceptacle of Fucus containing spores and abortive filamenfe. Tlie spores Escape at 

 the opening, o; other conceptacles contain antheridia. Fig, 484. Antheridia of a Sea- 

 weed (Fucms serratits), a, Antheridium, containing sperm atozoids, 6, Antheridium with two 

 spermatozoids havtag vibratile cilia attached. Fig. 485. Archegonium (sporangium) of a 

 seaweed containiag pear-shaped spores which germinate. 



T 



