366 DR. SARAH М. BAKER AND MISS M. H. BOHLING ON 
of marsh Fucoids, being very general among attached plants, but there, from 
the very nature of their origin, the new shoots can only replace weatherworn 
parts of the thallus and never maintain a separate existence. The fact that 
Fra. 15.— Fucus vesiculosus megecad limicola ecad volubilis. 4 nat. size. 
Attenuated form produced by low salinity of sea-water. Northey Island, Essex. 
in attached plants vegetative shoots arise chiefly in the lower covered parts 
of the thallus and during the winter months, leads us to surmise that a low 
concentration of the cell-sap, or humidity during exposure, favours the 
production of such buds. 
