The Algae 



461 



Fig. 281. Brown seaweeds, principally species of Fucus, Ascophyllum, and Laminaria, on 

 the coast of Nova Scotia at low tide. 



swollen ends of the branches. The reproductive organs, oogonia 

 and antheridia, are contained within hollow depressions (con- 

 ceptacles). The eight egg cells formed within each oogonium 

 are discharged into the sea and are there fertilized by the sperms 

 set free from the antheridia. The oospores germinate at once, 

 and from them the leathery plants develop. The rockweeds do 

 not produce swimming spores. 



In tropical waters species of Sargassum or gulf weed that are 

 related to Fucus are abundant. These forms are remarkable 

 for their resemblance to seed plants with leaves and berries. The 

 berry-like bodies are filled with air and aid in flotation. When 

 torn from their native rocks in the Caribbean, these alg£e drift 

 to all parts of the North Atlantic. 



The kelps. The third line of development is represented by 

 the kelps, which vary from forms a few feet in length {Laminaria), 

 with a root-like holdfast, a stalk,^ and a large, leaf-like blade, 

 to forms in which the stalk is terminated above by a float and 

 several branches each with one or more large blades. Here 

 belongs the Nereocystis of our own northwest coast, and the 



