35 



organs are long, slender, articulated, unbranched, 

 and project in F. platy carpus out of tlie mouth of the 

 conceptacle in the form of tufts — these help in the 

 absorption of nutrient materials. Sterile conceptacles 

 are often found — no doubt being produced to further 

 aid in the absorption of nutrient matter from the 

 sea water. 



The Antheridia are produced as lateral ramifica- 

 tions of branched hairs. Each antheridium consists 

 of a thin-walled oval cell, the contents of which go 

 to form numerous small antherozoids ; these are 

 pointed at one end, and each is furnished with two 

 unequal motile cilia ; the short one is attached to the 

 pointed or anterior end, and directed forwards ; the 

 longer one is attached laterally and directed back- 

 wards. The antherozoid consists of nuclear sub- 

 stance, and always shows one reddish-brown spot — 

 due to the presence of one and very occasionally two 

 colour bodies. It is at this spot that the lateral 

 cilium is attached. The nuclear substance is sur- 

 rounded by a thin layer of protoplasm — Kinuplasm. 

 The whole of the contents of the antheridium is not 

 used up, a little protoplasm is left. 



The Oo^onia. The formation of an oogonium 

 begins with a papillose swelling of a parietal cell of 

 the conceptacle ; the papilla is separated o:ff by a 

 septum, and divides as it grows in length into two 

 cells, a lower, the pedicel cell, and an upper, which 

 forms the oogonium. This swells up into a spherical 



