36 OPINIONS AND DISCOVERIES 



all animal matter, has been proved by chemical decompo- 

 sition to exist in sponges.* Motion, as already observed, 

 is not essential to animality ; and in their inertion, zoo- 

 phytes, especially sponges, approximate so nearly to vege- 

 tables, that it is only the peculiarity of their constituent 

 parts (which we are enabled to discover by the aid of che- 

 mical science) that separates them. It is not essential to 

 the formation and growth of animal substance, that a heart, 

 brains, or even intestines, or any viscera, should exist, no 

 more than it is, that all vegetables should possess roots." 



" Wliether motion has ever been discovered or not in 

 any species of sponge, is not, I conceive, of so much im- 

 portance as some naturalists would appear to consider. 

 Those who are solicitous in their inquiries after the animals 

 which they have supposed to construct the vesicular fabric 

 of sponges, and have expressed their surprise, that, in this 

 age of cultivated science, no one should yet have discover- 

 ed, — must have taken a very limited view of matter posses- 

 sing vitality, and have grounded their hypothesis only up- 

 on supposed analogy. Why should it be concluded that 

 sponges are only the nidi of insects or vermes; or why 

 should not organic matter possessing vitality without action, 

 exist ? If these philosophers expect to find polypes, or ver- 

 mes of any kind, to be the inhabitants of sponges, they will 

 be deceived. The true character of Spongia is that of a 

 living, inactive gelatinous flesh, supported by innumerable 

 cartilaginous or corneovis fibres or spicula, most commonly 



• " The odour produced in the combustion of sponges, and other zoo- 

 phytes, is similar to that of other animal substances, mixed with a pecu- 

 liar marine odour, well exemplified by oysters roasted in their shells ; 

 and which is very different from the effluvia of burning vegetable matter." 



