MICROSCOPICAL STUDIES IN MARINE ZOOLOGY. 



BY JAMES HORN ELL. 



Study IV. Sponges ; an Introductory Sketch. 



THE Jersey shore between tide-marks is veritable " Spongeland." 

 Scarlet, brick-red, orange, yellowish green, yellow, white, grey, 

 and black patches clothe the rocks in chequered mantle, and with the 

 vieing colonies of gaudy-colored compound asciclians, relieve in a 

 pleasant manner the sombre brown of the fucus-covered rocks. Yet 

 common though sponges are, they remained until comparatively 

 recent years a puzzle group to naturalists. Grant is generally 

 credited with having, in 1825, given the first great impetus in the 

 right direction, by his observations on the passage of minute water 

 currents into the sponge by numerous small pores and their emergence 

 by a few large openings. The following extract from the third 

 edition of the Encyclopaedia Britannica, 1797, will, however, prove 

 that our fine old pioneer naturalist, London merchant Ellis, should 

 rather have the credit: — "Mr. Ellis, in the year 1762, was at great 

 pains to discover these animals. For this purpose he dissected the 

 spongia urens, and was surprised to find a great number of small 

 worms of the genus of nereis or sea-scolopendra, which had pierced 

 their way through the soft substance of the sponge in quest of a safe 

 retreat. That this was really the case he was assured of, by inspect- 

 ing a number of specimens of the same sort of sponge, just fresh from 

 the sea. He put them into a glass filled with sea water, and then 

 instead of seeing any of the little animals which Dr. Peysonell 

 described, he observed the papillae or small holes with which the 

 papillae are surrounded, contract and dilate themselves. He examined 

 another variety of the same species of sponge and plainly perceived 

 the small tubes inspire and expire the water. He therefore concluded 

 that the sponge is an animal, and that the ends or openings of the 

 branched tubes are the mouths by which it receives its nourishment, 

 and discharges its excrements." 



The same work describes " Spongia," as " a genus of animals 

 belonging to the class of vermes, and order of zoophytes. It is fixed, 

 flexible, and very torpid, growing in a variety of forms, composed 

 either of reticulated fibres, or masses of small spines interwoven 

 together, and clothed with a living gelatinous flesh, full of small 



