244 



PHARMACEUTICAL BOTANY 



undergoes a resting stage and upon the advent of favorable condi- 

 tions develops into a new Ectocarpus filament. 



Fucus Vesiculosus (The Bladder Wrack). This form, a brown 

 alga, occurs as a flat thallus, which forks repeatedly, a type of 



T 



FIG. 119. Fucus vesiculosus. Receptacle cut transversely, c, conceptacle, 

 T, cellular thickness. (Magnified.) 



branching called dichotomous. It grows near the surface of sea 

 water, attached to rocks or to mussels along banks by means of a 

 basal disc-shaped holdfast. In the upper branches of the thallus are 



FIG. 120. Fucus vesiculosus. Section of a male conceptacle lined with branched 

 paraphyses which bear the antheridia (highly magnified). 



to be found air bladders which are more or less spherical and usually 

 in pairs. The tips of old branches become swollen and are termed 

 receptacles. They are dotted over with minute cavities called con- 



