52 P^rt second. 



The sponge of commerce {Euspongia, fig. 117) is of the form 

 we know in its domestic relations, but in life shows on its surface 

 the largest only of its numerous holes; over all the rest the dark, 

 slate-coloured flesh forms a continuous film. It is obtained by 

 diving, dredging, or harpooning with a long trident; the principal 

 marktes are at Trieste and Paris. Of the different kinds the finest 

 and most costly is the Levantine sponge {Euspongia officinalis) 

 which, in its varieties, extends on all the eastern Adriatic and 

 Mediterranean shores. It is not found west of Naples and on the 

 Italian coast no sponges occur in remunerative quantity, though 

 quite recently some beds have been discovered near Sicily. The 

 harder Zimocca sponge {Euspongia zimocca) from Asia Minor 

 and Egypt fetches about one tenth of the price, as does the large 

 coarse horse sponge {Hippospongia equina), found in all the Levant 

 and extending along Africa to the Straits of Gibraltar ; it is honey- 

 combed with wide holes. Of the last genus {Hippospongia) are 

 the American "glove sponge" and "sheeps-woll sponge"; their 

 "hard-head" is related to the European Zimocca, while their 

 "velvet sponge" and "grass sponge" are independent species. The 

 Bahamas and Caribbean Sea form the American sponge-field. — 

 After the removal of the soft parts of the sponge the fishermen 

 usually fill the skeleton with sand, so as to increase its weight 

 and thus to obtain a higher price for their goods. For this reason 

 it is necessary to rinse newly bought sponges repeatedly so as 

 to remove all foreign matter and it is well at first to add a little 

 hydrochloric acid to the water. — The sponge of commerce is 

 found rarely in the Bay of Naples. It chiefly frequents rocky 

 coasts and coral reefs; it does not live in very deep waters. 



Sponges have a great capacity for regeneration, which is in 

 general more highly developed in lower than in higher animals. 

 If a sponge be cut up in many pieces, each, under favourable 

 circumstances, continues to live and after some time attains the 

 full size again. It has been attempted to make use of this property 

 for the commercial cultivation of sponges, but it did not prove 

 remunerative and was given up. 



Besides the Bath-sponge the Aquarium contains various flinty 

 sponges conspicuous by shape or colour, as, for instance, the 

 beautiful orange-red bushes of Axinella (fig. 119) looking like 

 corals, the yellow balls of Tethya (fig. 118) and the dirty white 

 lumps of Geodia. On the minute flint anchors which are scattered 

 over the surface of the last mentioned form many animals and 

 even fishes become attached. Thus caught they die and their 

 decomposing bodies serve as food for the sponge. Other flinty 

 sponges grow in the form of incrustations over stones and plants, 

 and there are forms which settle on other animals and even serve 

 them as houses. (Suberites, see p. 83.) The chalky sponges 

 {Calcarea) are mostly small, and either grey or white. A fair 



