FLORIDE.& 



209 



(Hypngea, Lmx.), GELIDIACE^E (Gelidium, Lmx., &c.), SPONGIOCARPE^E 

 (Polyides, Ag.), LOMENTARIACE^: (Lomentaria, Gaill.), RHODOMELACE^E 

 (Laurencia, Lmx., Chondria, Ag., Rhodomela, Ag., Polysiphonia, Ag., 

 Rytiphlaea, Ag., Amansia, Lmx., Vidalia, Ag., Dasya, Ag., Pollexfenia, 

 Harv., &c.), SPYRIDIACE^: (Spyridia, Harv.), and WRANGELIACE^E (Sper- 

 mothamnion, Aresch., Bornetia, Thur., Lejolisia, Born., Wrangelia, Ag., 

 &c.). A peculiar mode of fertilisation is described in the case of 

 Gracilaria confervoides (Grev.). The procarp is composed of six or seven 

 cells, and its position is indicated by an external swelling on the 

 * frond ; ' the pericarp is 

 formed before fertilisation. 

 The cells both of the pro- 

 earn and of the placenta 

 fuse together by the dis- 

 appearance of their cell- 

 walls ; and the fused cells 

 of the procarp and of the 

 placenta are placed in 

 communication with one 

 another by protoplasmic 

 protrusions or diverticula, 

 proceeding from the fused 

 cells of the procarp and 

 passing through their 

 swollen walls. The cells 

 which form the free sur- 

 face of the placenta now 

 produce radiating rows of 

 spores formed basipetally, 

 while from the fused pro- 

 carpial cells other diverti- FIG 

 cula arise which also form 

 spores at their free ends 



independently of the placental cells. It would appear as if by this 

 means a portion of the protoplasm of the pollinoid were conveyed 

 through the trichogyne and the procarpial cells, which play the part of 

 the auxiliary cells of Dudresnaya, to the placental cells. In Polyides 

 the cystocarps are congregated in external amorphous wart-like ex- 

 crescences formed of vertical confervoid filaments, of which the carti- 

 laginous ' frond ' is almost entirely composed, set in firm jelly. 



Plocamium coccineum (Huds.) is one of the most abundant of our 

 red seaweeds. Rhodymenia palmata (Grev.), a very common red seaweed, 



86. Rhodymenia Palmetto. Grev. a, with tetraspo- 

 ranges (natural size) ; ft, section through apex of frond with 

 tetrasporanges ( x 100). (After Ktitzing.) 



