OF THE NATURE OF SPONGES. G9 



green SpongTlla would hesitate to pronounce it a vegetable, 

 a conclusion which the exacter observation of the naturalist 

 seems to have proved to be correct; and when we pass on from 

 it to an examination of the calcareous and siliceous marine 

 genera, the impression is not so much weakened but that we 

 can still say, with Professor Owen, " that if a line could be 

 drawn between the animal and vegetable kingdoms, the 

 sponges should be placed upon the vegetable side of that 

 line."* We shall possibly, however, arrive at an opposite 

 conclusion if, proceeding in our enquiry, we follow the 

 siliceous species insensibly gliding, on the one hand, into the 

 fibro-corneous Sponge filled with its mucilaginous fishy 

 slime, and on the other into the fleshy Tethya in whose 

 oscula the first signs of an obscure irritability show them- 

 selves. Sponges therefore appear to be true zoophytes ; 

 and it imparts additional interest to their study to consider 

 them, as they probably are, the first matrix and cradle of 

 organic life, and exhibiting before us the lowest organiza- 

 tions compatible with its existence. 



- The Lancet, No 871, p. 22 j. 



