280 FTJCUS. 



rim by a round hole, through which protrude hairs which spring 

 from the tissue lining the cavity, the latter also containing muci- 

 lage ; the young conceptacle is closed, and the hairs are seen to arise 

 from single cells of the lining tissue ; in successively older regions 

 of the thallus the conceptacles become closed again, the projecting 

 portions of the long hairs dying off, while the opening of the cavity 

 is obliterated by bundles of shorter unicellular hairs which grow 

 from the lining tissue, as well as by the bases of the long hairs and 

 by brown mucilage. 



406. Sexual Organs and Cells (Figs. 59, 60). Before 

 making sections of the conceptacles, study the free sexual 

 organs (autheridia and oogonia) and sexual cells (an- 

 therozoids and oospheres). 



Fig. 59. Fucus. Four Antheridia, borne on one of the branched hairs 

 in a Male Conceptacle. 



Place fresh fertile plants in a large vessel of sea -water 

 or sea-salt solution, and after about six hours hang up the 

 plants or lay them in a dry place for about six hours ; note 

 that drops of mucilage ooze from the fertile branch tips 

 orange coloured in the male plant, green in the female 

 plant, 



