XIV. ALG^. 



971 



Fucus vesiculosus. 



Tubercle cut transversely. 



c, conceptacle ; T^ cellylar thickness 



o£ thd tubercle (mag.) , 



Fucus vesiculosus. Fertilization. 



Ay spore approaclied by antherozolds ; 



Bf spore on wbicli the antherozoids have 



fixed themselves (mag.). (Thuret.) 



Fucus vesiculosus. 



Fertilized spore, larger, surrounded by a 



mucilaginous membrane, and in which , 



appear the first indications of division 



(mag.). (Thuret.) 



Fucus vesiculosus. 

 Section of a J conceptacle lined with branched hairs bearing the antherldia. 



Fucus vesiculosus. Section of a Q conceptacle. 

 0, osteole by which the spores escape. (Thuret.) 



Marine Algoe^ brown or olive, mucilaginous, very various in form : stemless or 

 caulescent, rounded or elongated, formed into a cup (Himanthalia), or cord (Chorda), 

 or plate {Laminaria), or fan {Padina) ; frond with or without nerves, entire or vari- 

 ously, cut, sometimes pierced vyith holes (Aga/rum), or twisted into a spiral {Thalas- 

 siophyllum), or furnished with floating bladders {Sa/rgassum, Macrocystis, &c.), or with 

 a fistular stem {EcMonia huccinalis, Nereocystis, &c.). Ebpbodttctivb or(JANs, 

 superficial sporangia under the form of sori ; spores, sometimes proceeding from the 

 condensation of the colouring matter of the fronds (trichosporangia), very small, 

 furnished with vibrating hairs and endowed with the power of motion, sometimes 

 resulting from a true bisexual fertilization, and then monoecious or dioecious ; the $ 

 (oosporangia) either external or conceptacular, containing 1, 2, 4, 8 large ovoid or 

 globose motionless spores j antheridia sessile or in branches, oblong or linear; 



