SPONGES. 



27 



with the crimson and green specimens. You have never 

 doubted that these are all sea-weeds, that is plants, alike. 

 And yet if you saw these growing on their native rocks, 

 plant-like as they are in form, you might discern, on careful 

 examination with a pocket lens, that from various points 

 of their surface tiny star-like circles of radiating points 

 were protruding, that possessed spontaneous motions, and 

 exhibited a shrinking sensitiveness to danger, and a power 

 of seizing and swallowing food ; and you would suspend, if 

 not alter, your judgment. 



If now, we ask, What is an animal 1 you will confess 

 that the answer is not so easy as it appeared at first ; still 

 there remain some characters common to all the beings 

 that we have glanced at, and these we may perhaps con- 

 clude to be inseparable from, and distinctive of, animal 

 existence. Of these characters, the most constant and the 

 best defined are the power of spontaneous motion, and the 

 possession of a stomach, or at least an enclosed cavity, in 

 which other substances are converted into nutriment. 



With regard to the former of these characters, what 

 shall we say to the Sensitive plants of the tropics, the 

 pinnate leaflets of which fold together, and the jointed 

 leaf-ribs fall, on the rude touch of a foreign body % What 

 to the plant called Venus' Fly-trap (Dioncea muscipula), 

 found in the marshes of North America, whose broad 

 two-lobed leaves, armed with strong teeth standing up 

 from the surface, ordinarily lie widely expanded; but 

 when an insect touches their hairy centres, instantly fly up 

 like a rat-gin, the teeth cross each other, and the offend- 

 ing fly is pierced, and held a prisoner until it dies ? What 

 to the Gorachand of Bengal (Hedysamm gyrans), whose 



