[4] 74 ALG.ffi 



Bladder-wrack (Fucus) continued. 



C. Examine a longitudinal section of the stalk of the thallus. Draw (a) the surface layer of square or oblong 

 cells with brown phaeoplasts, (b) the longitudinally running conducting cells with abundant contents and perforated 

 cross walls, and (c) the longitudinally running thick-walled fibres. 



D. Examine a transverse section through the reproductive part of the thallus. Note the assimilating cells 

 on the surface and the loose tangle of conducting cells in the centre. Draw a conceptacle containing (a) oogonia, 

 with eight egg-cells when ripe, (b) the antheridial branches, bearing the long oval antheridia with dense contents, 

 (c) the sterile hairs. 



E. In fresh material notice the antherozoids (sperms) and egg-cells (ova) extruded from the mouth of the 

 conceptacle. Mount some of these in sea-water and observe the movements of the sperms. 



