THALLOPHYTA. 



FLOKIDE^. 

 POLYSIPHONIA PASTIGIATA, Grev. 



I. This seaweed is found on all our coasts, growing 

 in dense reddish-brown tufts, which are fixed firmly on 

 to the thallus of Ascophyllum (Ozotkallia) nodosum, 

 Le Jolis. It grows to a length of about two inches, and 

 the thin cylindrical thallus is frequently branched in an 

 apparently dichotomous manner : on some of the plants 

 taken in autumn there may be recognised with the 

 naked eye, or with a simple lens, roundish bodies borne 

 laterally (cystocarps) ; on others irregular yellowish 

 tassels at the ends of the branches, these are the 

 antheridia, and they are best seen on specimens taken 

 in early summer ; on others again dark irregularly dis- 

 posed swellings may be recognised in the substance of 

 the thallus, these are the organs of vegetative repro- 

 duction (tetraspores). 



II. The material to be used for microscopic investi- 

 gation should be either quite fresh, and be kept, and 

 mounted in salt water, or better in weak glycerine 



D 2 



