Chap. 69.] SPONGES. 455 



j thick, very hard, and rough, and are called ''tragi:'"" the 

 second, are thick, and much softer, and are called " mani i'"** 

 of the third, being fine and of a closer texture, tents for sores 

 are made ; this last is known as " Achillium."*^ All of these 

 sponges grow on rocks, and feed upon^ shell- and other 

 fish, and slime. It would appear that these creatures, too, have 

 some intelligence ; for as soon as ever they feeP'^ the hand 

 about to tear them off", they contract themselves, and are sepa- 

 rated with much greater difficulty : they do the same also 

 when the waves buff'et them to and fro. The small shells that 

 are found in them, cleaiiy show that they live upon food : 

 about Torone^® it is even said that they will survive after they 

 have been detached, and that they grow again from the roots 



of sponges, but that Pliny here is only enumerating those which were em- 

 ployed for domestic use. 



43 In the singular, '' tragus," from the Greek rpaybg, a goat, on account 

 of their strong smell, which they contract from the mud and slime in which 

 they are found. 



4* Probably from the Greek ^a'vog, "rare," "in small quantities;" in 

 allusion to the comparative rarity of this kind of sponge. 



*5 A term merely used, as Caelius Rhodiginus says, to denote the strength 

 of its texture. 



*s Cuvier says, that though sometimes shells and small animals are found 

 lodged in the sponge, they do not afford it any nourishment. Having no 

 mouth, it can only live and increase by the inhalation of substances dis- 

 solved in the water of the sea. 



*^ " Sensere." Cuvier says, that many observers have stated that this is 

 the only sign of animal life that the sponge affords ; but that Grant assures 

 us that "it does not even afford that. The fact is, however, that " the sponge 

 itself is a cellular, fibrous tissue, produced by small animals, almost imper- 

 ceptible, called polypi, and living in the sea. This tissue is said to be 

 covered in its native state with a sort of semifluid thin coat of animal jelly, 

 susceptible of a slight contraction or trembling on being touched ; which, in 

 fact, is the only symptom of vitality displayed by the sponge. After death, 

 this gelatinous substance disappears, and leaves only the skeleton or sponge, 

 formed by the combination of a multitude of small capillary tubes, capable 

 of receiving water in the interior, and of becoming thereby distended. 

 Though different in their nature, sponges are analogous in their formation 

 to coral. On being examined with a power of about 500 linear, the fleshy 

 matter of the living sponge is to be distinctly observed, having in its interior 

 gemmae, which are considered to be the young. These are occasionally 

 given off from the mass of living matter. The greater portion of the mass 

 of sponge consists of small cylindrical threads or fibres, varying in size. 

 The spiculae are not found within these, but in the large and flattened 

 fibres, and varying in number from one to three or more, imbedded in their 

 substance." From Brande's Dictionary. 



48 See B. iv. c. 17. 



