and Functions of' the Sponge. 123 



SpongillafnaUlis (Fig. 1.), but larger. In general, however, 

 the only difference observed among the silicious spicula of the 

 same individual is a great variety in their size. Donati not only 

 observed that the hard spicula of the Tethya sphoerica differed 

 remarkably in size, but likewise, that they were bound together 

 by a peculiar fleshy or tendinous matter, (Mar. Adr., p. 62). 

 In the S. coalita, besides the slender curved fusiform spiculum 

 (Fig. 2.), we observe a long thick spiculum of the same form, 

 which extends along the sides of two or three successive pores, 

 and contributes much to their strength in a species peculiarly 

 liable to have the diameter of these passages disturbed from the 

 flexibility of its branches, and their erect position at the bottom 

 of the sea. 



At the approach of death, and during putrefaction, the soft 

 gelatinous or cellular matter of the S. panicea escapes plentifully 

 from every opening of the body, and drops down like the ropy 

 transparent colourless matter of an egg, without loosening, in the 

 slightest degree, the connecting matter of the spicula, or alter- 

 ing perceptibly the form of the skeleton. When we extract, by 

 strong pressure, the cellular matter from the S. coalita, S. to- 

 mentosa, &c. we obtain a very tough leathery substance, com- 

 posed of spicula firmly bound together by the cartilaginous mat- 

 ter, and retaining the original colour and form of the sponge. 

 By repeatedly and strongly agitating a thin portion of the recent 

 S. papillaris in fresh water, and then examining it under a pow- 

 erful microscope, we find that the cellular matter has been en- 

 tirely washed away, and the spicula are left imbedded in a trans- 

 parent homogeneous tough matter, which retains its original co- 

 lour and form unaltered. This connecting matter tears like a 

 piece of cartilage, emits a fishy odour when burnt, dissolves with- 

 out effervescence in nitric acid, contracts much, and acquires 

 an amber colour by drying, and becomes very brittle in the 

 dried state, probably alone from the earthy spicula it contains. 

 There seems, therefore, to be a distinct matter in the earthy 

 sponges for connecting, and probably secreting, the spicula of 

 their skeleton. The dried preparations of this animal, preserved 

 in museums, owe their form and stability to this tendinous con- 

 necting substance, and, from its close resemblance in the dried 

 state to the amber coloured filaments of horny species, it is pro- 



