878 THE INHABITANTS OF THE SEA. 



CHAP. XVIII. 



PHOTOZOA. 



The Foraminifera. — The Amoebae — Their "Wonderful Simplicity of Structure. — The 



Polycystina. — Marine Infusoria. — Sponges — Their Pores — Fibres and Spiculse 



The Common Sponge of Commerce. 



Think not, reader, that the life of the ocean ends with the 

 innumerable hosts of fishes, molluscs, Crustacea, medusae, and 

 polyps we have reviewed, and that the waters of the sea or the 

 sands of the shore have now no further marvels for us to ad- 

 mire. The naked eye indeed may have attained the limits of 

 life, but the microscope will soon reveal a new and wonderful 

 world of animated beings. 



Take only, for instance, while wandering on the beach, a 

 handful of drift-sand, and examine it through a magnifying 

 glass. You will then not seldom find, 

 among the coarser grains of inorganic 

 silica, a number of the most elegant 

 shells ; some formed like ancient am- 

 phorae, others wound like the nautilus, 

 s^ta. aiscoidaiJ but a11 shaped in their minuteness with 



a. Natural size. a perfection which no human artist 



b. c. The Bame, highly magnided. , - . -i • , i 1 , 



could hope to equal in the largest size. 



The knowledge of these charming little marine productions is 

 of modern date, for they were first observed in the sand of the 

 Adriatic by Beccaria in 1731, and for some time believed to 

 belong exclusively to that gulf. At a later period some species 

 were discovered here and there in England and France, but 

 their universality and importance in the economy of the ocean 

 were first pointed out in 1825, by the distinguished French 

 naturalist Alcide d'Orbigny. 



The sand of many sea-coasts is so mixed with Foraminifera, as 

 they have been called from the openings with which their shells 

 are pierced, that they often form no less than half its bulk. 



