HALF AN HOUR WITH SEAWEEDS. 39 



Fig. 8, a). The former are usually regarded as the 

 male, and the latter as the female organs. In every 

 case, both are produced on separate plants. The 

 antheridia are little bags containing small bodies 

 called zoospores (6). These no sooner escape in the 

 way mentioned, than they move about in the water 

 as if they were little animals, and not plants at all. 

 The spores are little grains of an oblong shape, which 

 ultimately separate into a certain number of parts (c). 

 These perform the functions of seeds, which are 

 fertilised by the zoospores, just as the ovules are by 

 the pollen of flowering plants. The serrated wrack 

 (Fucus serratus) resembles the vesiculosus in its 

 general form, but it may at once be distinguished 

 by its having no air-bladders, and by the edges of 

 the fronds being serrated. Like the former, its fruit 

 is borne at the tips of the fronds. Indeed, this 

 species is usually recommended as the best for 

 microscopical examination of the phenomena we have 

 been describing. Professor Harvey advises that fresh 

 specimens should be collected in winter or early 

 spring, and, being removed from the water, that 

 they should be left till they were partially dry. As 

 the surface dries there will exude from the pores of 

 the receptacle drops of a thick orange-coloured fluid, 

 which, on being placed under a microscope and 

 moistened with salt water, will be seen to be composed 

 of innumerable cellules, from which will issue troops 

 of these atoms. No sooner are they liberated, than 

 they commence those singular zoosporic motions 



