ALGAE. — RHODOPH YCEAE. 



79 



segmented filaments and produce a closed envelope, which opens after a time at the 

 apex, the trichogyne and trichophore being still to be seen outside it (Fig. 51, tg).~\n 

 the RhodoMELEAE the envelope of the fructification appears in its rudimentary form 

 as a circular wall. We noticed a similar investment of the sexually generated 

 spores in Coleochaefe, a genus of the Chlorophyceae, while the oosphere of Chara has a 

 similar covering before fertilisation ; but we shall lay no great stress on this difference, 

 if we take into consideration analogous cases in other plants. For instance, the arche- 

 gonia oi Marchantia have an outer covering, which exists in a rudimentary form before 

 fertilisation, but developes only after fertilisation, while the archegonia oi Junger- 

 manni'a, another of the Hepaticae, are invested before fertilisation and quite in- 



FlG. 51. Lyolisia ni€diteyra}iea, A small piece of a creeping filament with a rhizoid and an erect branch, the 

 ower cell of which bears a branch with tetragonidia tt. 5 a sexual (monoecious) plant ; iu rhizoids of the creeping stem, 

 the apical cell of which is at s and its erect branches bear the se.xual organs ; a a antheridia, in which the axile cell-row 

 is unfortunately not shown ; tg trichogyne beside the apex t of the fertile branch ; k the envelope of the sporocarp ; at 

 sp a spore which has escaped from the sporocarp. C an empty sporocarp, the outer covering of which is formed of 

 cell-rows. After Bornet, Ann.d. sc.-nat. 1859, magn. about 150 times. 



dependently of it ; but in this case the outer covering encloses a whole group of 

 archegonia ; similar cases might be adduced from the Phanerogams. 



There are other Florideae in which the organs of fertilisation are of a more complex 

 character. This is the case with the Corallineae'. In this group, which includes 

 the Melobesieae mentioned above, the walls of the vegetative cells are thickly incrusted 

 with calcium carbonate. The thallus of the Melobesieae takes the form of creeping 



' Solms-Laubach, Corallina (Aus Fauna u. Flora des Golfes von Neapel u. d. angrenzendeii 

 Meeiesabschnitte, herausgeg. von d. Zool. Station in Neapel, IV. Monographie, Leipzig, 1881). 



