87 



the rocks. This opinion of their possessing a degree of animal lite 

 was also entertained in the time of Pliny. Count Marsilli* confirmed 

 this opinion by observing, on their being taken out of the sea, a sys- 

 tolic and diastolic motion, in certain little round holes, which lasted 

 until the water they had contained was quite dissipated. Mons. 

 Peysonell supposed sponges to have been formed by certain worms, 

 which inhabited the labyrinthean windings of the sponge ; and be- 

 lieved, that whatever life was found in these substances, existed in 

 these worms, and not in the substance of the sponge, which he was 

 convinced, was an inanimate body. This point was, however, deter*- 

 mined by Mr. Ellis, who, in a letter to Dr. Solander f> relates the 

 observations which he had made ; by which he ascertained, that these 

 worms, which he found in the sponge in great numbers, were a very 

 small kind of nereis, or sea scolopendra; and that they were not the 

 fabricators of the sponge, but had pierced their way into its soft sub- 

 stance, and made it only their place of retreat and security. Upon 

 examining, in sea water, a variety of the crumb of bread sponge, 

 the tops of which were full of tubular cavities or papillae, he could 

 plainly observe these little tubes to receive and pass the water to 

 and fro ; so that he inferred, that the sponge is an animal mi generis, 

 whose mouths are so many holes or ends of branched tubes, opening 

 on its surface ; with these, he supposes, it receives its nourishment, and 

 discharges, like the polypes, its excrements. 



Mr. Ellis also discovered, that the texture is very different in diffe- 

 rent species of sponge : some being composed wholly of interwoven 

 reticulated fibres, whilst others are composed of little masses of straight 

 fibres of different sizes, from the most minute spiculae to strong elas- 

 tic shining spines, like small needles of one-third of an inch long; 

 besides these, he observes, there is an intermediate sort, between ths 



* Histoire Physique de la Mer, p. 53. 

 t Phi], Trans. Vol. LV. p. 2SO. 



