FUCUS VESICULOSUS. 



75 



frond or leaf is flat ; the branches, irrespective of lateral displace- 

 ments, all lie on one plane though often twisted spirally are 

 thick, linear, and entire at the margin, branches by twos, is fur- 

 nished with quite a prominent mid-rib. The air vessels, or blad- 



Fig. i. Fucus Vesiculosiis. Natural Size. a. Air Bladder, b. Fer- 

 tile end of the Frond. 



ders, are globose or elliptical, formed by inflation of the substance 

 of the stem or branch ; are mostly found in pairs, though some- 

 times absent. The substance is coarse and thick. The ends of 



Fig. 2. Cross Section of one of the tips of Fucus rcsiiii/osits. (x 



diameters?} 



the branches are enlarged, forming bladder-like receptacles, having 

 their surface covered with protuberances, ellipsoid, oval or spindle- 



