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in the pith the analogue of the nervous system of animals ; 

 but nothing can be more improbable ; and many perfect 

 plants contain no pith. But, then, there are likewise many 

 animals, e.g.^ various species of polyps, in which no nervous 

 system has, as yet, been discovered. 



6. With respect to the functions, that of sensation, in 

 whatever organized being it can be proved to exist, may be 

 regarded as a sufficient proof of its animal nature ; but the 

 difficulty lies in the proof. In invertebrated animals, we 

 have no proof of their possessing sensation, except their 

 movements or sounds, when painful impressions are made 

 on their bodies. But are these any better proof of sensation 

 on their part, than are the curious motions of the sensitive 

 plant, and several other evidently vegetable beings, when 

 struck or irritated ? Besides, the class of movements to 

 which physiologists give the name of reflex, and which 

 cannot be distinguished from those which are voluntary and 

 accompanied with sensation, may take place in the paralysed 

 limb of a human being deprived of all sensation, or in the 

 body of an animal from which the brain has been removed ; 

 even in the tail of a lizard separated from the body. As 

 we cannot prove the existence of sensation in all animals, 

 nor even, very satisfactorily, its absence from all vegetables, 

 this will not serve as a distinctive character. 



7. Still less will the power of effecting automatic move- 

 ments serve our purpose ; for we see this existing in many 

 plants, as the Dionoea muscipula, the Mimosa sensativa, the 

 stamens of the common barberry, the stigma of various 

 species of Mimulus, &c. Nor yet is locomotion an animal 

 characteristic exclusively, nor invariably ; zoophytes are 

 rooted like plants to submarine rocks, and oysters are 

 chained for life to the banks on which they grow ; oppositely, 

 some of the lowest vegetable forms present strange loco- 

 motive movements during certain periods of their existence ; 



