8 



as in the modern. In the warmer areas, again, the water 

 teems with the minute phosphorescent Noctiluca. 



The Cilioflagellates, such as Peridinium and Ceratium, 

 occur in great abundance throughout the year. In the warmer 

 months these and the pelagic Infusoria (e.g. Tintinnus) are 

 especially conspicuous at the surface. Their multiplication 

 and that of other free and parasitic Infusorians — upon which 

 many simple forms and even fishes feed — is beyond the sphere 

 of human influence. 



Amongst the lower invertebrates we meet with a group 

 which in itself has been the source of a special fishery, viz. the 

 sponges. From time immemorial the Levant and for a less 

 period the Bahamas and Florida have furnished large supplies. 

 Moreover, comparatively little care has been taken to propagate 

 them by artificial means, and yet so nicely do all the surround- 

 ings fit them to continue the race that, after all these years, no 

 sign of extinction is apparent. The fragments left on the 

 rocks or stones as well as the pelagic larvae which represent 

 them in the water around have sufficed to fill up the gaps 

 caused by the sponge-fishermen. 



The non-commercial kinds of sponge, on the other hand, 

 are free from special pursuit, being only captured by trawls 

 and hooks to be again returned to the sea. The lacerated 

 fragments or their contained eggs and larvse enable each species 

 to keep up its numbers in all our seas. Storms, moreover, 

 toss many on the beach, but neither the one loss nor the other 

 affects their abundance. Nature persistently carries out her 

 measures of economy from age to age, and no more conspicuous 

 example of this exists than the wide-spread disintegration of 

 limestone rocks and the densest shells by the ceaseless borings 

 of a sponge (Cliona). 



In no group are the resources of the sea in regard to re- 

 cuperation more prominently exhibited than in the hydroid 

 zoophytes, jelly-fishes, anemones and corals. The hardihood of 

 the common freshwater Hydra, so graphically told by Abraham 

 Trembley, the old naturalist of Geneva, is characteristic of the 

 majority of the race. The immense profusion of such zoophytes 

 as Obelia in inshore waters and the rapidity of their growth 



