168 CRYPTOGAMOUS OR FLOWERLESS PLANTS. [SECTION 17, 



shaped pieces, with an internal stalk, and bearing long and ribbon-shaped 

 filaments, which consist of a row of delicate cells, each of which dis- 

 charges a free-moving microscopic thread (the analogue of the pollen or 

 pollen-tube), nearly in the manner of Ferns and Mosses. One of these 

 threads reaches and fertilizes a cell at the apex of the nucleus or solid 

 body of the sporocarp. This subsequently germinates and forms a new 

 individual. 



507. Algae or Seaweeds. The proper Seaweeds may be studied by 

 the aid of Professor Farlow's "Marine Algae of New England;" the 



fresh-water species, by Prof. H. C. Woods's "Fresh-water Algse of North 

 America," a larger and less accessible volume. A few common forms are 

 here very briefly mentioned and illustrated, to give an idea of the family. 

 But they are of almost endless diversity. 



508. The common Rockweed (Fucus vesiculosus, Fig. 554, abounding 

 between high and low water mark on the coast), the rarer Sea Colander 

 (Agarum Turneri, Fig. 553), and Laminaria, of which the larger forms 

 are called Devil's Aprons, are good representatives of the olive green or 

 brownish Seaweeds. They are attached either by a disk -like base or by 

 root-like holdfasts to the rocks or stones on which they grow. 



509. The hollow and inflated places in the Fucus vesiculosus or Rock- 

 weed (Fig. 55i) are air-bladders for buoyancy. The fructification forms 

 in the substance of the tips of the frond : the rough dots mark the places 

 where the conceptacles open. The spores and the fertilizing cells are in 

 different plants. Sections of the two kinds of conceptacles are given in Fig. 

 555 and 556. The contents of the conceptacles are discharged through 



Fig. 555. Magnified section through a fertile conceptacle of Rockweed, showing 

 the large spores in the midst of threads of cells. 556. Similar section of a sterile 

 conceptacle, containing slender antheridia. From Farlow's " Marine Alga; of New 

 England." 



