Note 2742 — BOOK IX. THE NATURAL HISTORY OF FISHES. (continued 2)

“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 imperceptible, 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 gemmæ, 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 spiculæ 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.