THE MARINE BOTANIST. 189 



Fructification: 1. Conceptacles {favellidia) glo- 

 bose masses of spores immersed in the frond, or in 

 swellings of the branches. 2. Tetraspores variously 

 dispersed. 



This, the largest tribe of the red series, includes 

 twenty- one British genera. In outward appearance 

 and habit the species differ greatly from one another ; 

 but the structure in all is similar, consisting of arti- 

 culated threads more or less firmly combined toge- 

 ther. In Dudresnaia, when viewed through the 

 microscope, the frond will be seen to consist of Httle 

 bundles of filaments radiating from the centre ^ but 

 in the plants of denser substance this structure can- 

 not be seen, unless a portion of the frond be soaked 

 for some time in fresh, or plunged for an instant 

 into boiling water. Dr. Harvey says : '' A pieco 

 of Gigartina acicularis thus treated will be changed 

 into a body having the appearance, under the micro- 

 scope, of a Dudresnaia or Nemaleon." Wart-like 

 prominences, called NematJieciay are common to 

 many of the genera : these are described as consist- 

 ing at first wholly of vertical filaments ] but, after 



