OF THE NATURE OF SPONGES. 37 



ramified or reticulated, and furnished more or less with ex- 

 ternal pores or small mouths, which absorb the water, and 

 which is conveyed by an infinity of minute channels or ca- 

 pillary tubes throughout every part of the body, and is 

 there decomposed, and the oxygen absorbed as its princi- 

 pal nourishment, similar to the decomposition of air in the 

 pulmonary organs of what are called perfect animals. 



" The food of sponges," Montagu continues, " must be 

 similar to that of plants ; for a sponge has no more power 

 to digest gross bodies than a Fucus or a Conferva ; and 

 nothing can be more admirably adapted to a gaseous ali- 

 ment than the consti-uction of a sponge. The conformation 

 of a sponge better entitles it to the appellation of sea-lungs 

 than any other marine production, since the water absorbed 

 by its capillary tubes becomes as greatly divided, as air re- 

 spired by pulmonary organs ; and thus, by such an exten- 

 sive surface ojffered to the water, decomposition may be 

 effected in the same way as air is decomposed in the lungs 

 of terrestrial animals."* 



The observations of Bosc on the species of this family 

 are of little value. He thinks their appearance, consisting 

 as they do, of a tissue of fine fibres interlaced in every di- 

 rection, such as we see exhibited in the structure of some 

 aquatic confervge, renders the error of those natm-alists who 

 have taken the sponges to be plants very excusable ; but 

 the fact which proves their animality is the odoiu* they ex- 

 hale in burning, although it had been attempted to inva- 

 lidate this conclusion by saying that the smell might ra- 



* An Kssay on Sponges, with Descriptions of all the Species that have 

 been discovered on the coast of Great Britain, by George Montagu, &c. 

 in the Wernerian Memoirs, ii. p. 71-75. Kdin. 1818. The paper was 

 read to the Society on 9th March 1812. 



