ON ZOOPHYTES AND JELLY-FISHES. 9 



show the ever ready resources of nature in restoring losses and 

 spreading useful forms on every suitable site. Though it were 

 possible in a given area to remove every vestige of such a form 

 from the sea-bottom, a single summer tide would carry a 

 sufficiency of little ripe jelly-fishes (Hydromedusce) to repeople 

 it. The countless swarms of these graceful and beautiful glassy 

 creatures, which stretch for miles round our shores and far 

 beyond into the open ocean, is one of the most striking features 

 in marine life. From the eggs of these swimming jelly-fishes 

 larvae arise which by-and-by settle on rocks, stones, salmon 

 stake-nets and other zoophytes, indeed, upon everything that 

 affords a suitable hold, and rapidly grow into the plant-like 

 original with which the cycle commenced. In their pelagic 

 condition they are for the most part unaffected by any mode of 

 fishing, though they are often beached in multitudes by the 

 tide. Nature herself in another instance ordains an annual 

 check to growth on the mussels of the Eden, for the dense and 

 graceful tufts — heavily laden with young mussels — are swept 

 off in October. But before this happens the spore-sacs of the 

 zoophyte (Gonothyrea) have given rise to multitudes of pelagic 

 young which ere long renew the feathery coating on the mussels. 

 Some of this group, again, such as Gorymorpha, live 

 immersed in sand, and are difficult to dislodge, even when 

 specially sought after by trawl, dredge or net. Thus a large 

 species obtained in considerable number? on the ground-rope 

 and trawl of the 'Medusa' in 1884 in St Andrews Bay has 

 never been procured since, notwithstanding various efforts. 

 Yet the free-swimming jelly-fishes it apparently throws off are 

 common at certain seasons, showing that the parent-stock still 

 remains. A rare plant (e.g. Asplenium septentrional e of 

 Stenton Crag) can readily be extirpated by the hand of man, 

 but it is otherwise with the denizens of the sea. It is not 

 easy, indeed, to check the growth of such marine animals, 

 amidst which other types lurk and feed, in turn to become 

 sustenance for the food-fishes, which occasionally, as in the 

 young cod, browse directly on certain zoophytes. Even the 

 gigantic whales engulph many of the little jelly-fishes mingled 

 with other forms on their feeding grounds in the Arctic Ocean. 



