1G8 CRYPTOGAMOUS OR FLOWERLESS PLAxNTS. [SECTION 17. 



shaped pieces, with au iulerual stalk, and bearing long aud ribbuu-shaped 

 fdameiits, which cunsist of a row of delicate cells, each of vvhicli dis- 

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

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

 threads reaches aud fertilizes a cell at the apex of the nucleus or sohd 

 body of the sporocarj). This subsequently germinates aud 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 Algae of North 

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

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

 But tliey are of almost endless diversity. 



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

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

 (Agarum Turneri, Fig. 5b'-\), and Laminaria, of which the larger forms 

 are called Devil's Aprons, are good rejn-esentatives 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 lioUow and inflated places in the Fucus vesiculosus or Rock- 

 weed (Fig. 551) are air-bladders for buoyancy. The fructification forms 

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

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

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

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



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

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

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

 England." 



