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<f The pigeon, likewise, which, from losing its brain, has 

 been deprived of its sensation and volition, still retains the 

 power of flying when thrown into the air. 



" Again, if we are to consider shrinking from an irritating 

 canse, and an attempt to withdraw from violence, a proof of 

 the existence of pain, in what way shall we convince ourselves 

 that the sensitive plant and other vegetables do not suffer ? 

 If we touch the leaves of the former they instantly withdraw 

 themselves, and the whole will droop as if they were dying from 

 the result of injury ; yet, who can imagine that any real sen- 

 sation is present ; i. e., that there are not only nerves capable of 

 receiving impressions, but also a nervous centre capable of 

 interpreting, as it were, the impressions transmitted to it. 



" Having thus demonstrated the fallaciousness of all our 

 means of judging of the existence of pain in others, let us 

 turn to the more special grounds we have for believing that 

 the lower animals cannot feel pain. 



" We have, in the first place, to remark that all sensation is 

 a mental act ; and that, without the concurrence of the mind, 

 no impression, whether calculated to produce pain or pleasure, 

 can be distinguished. Dr. Todd remarks upon this point, — 

 'a state of the sensitive organs, and a corresponding perception 

 by the mind, must concur to produce sensation, either condi- 

 tion may exist alone ; but then, the phenomenon is not a true 

 sensation, in the acceptation here given of the word. Thus, 

 light falling on the eye, in sleep, may excite the whole visual 

 sensitive apparatus, while the organ of perception is inactive. 

 On the other hand, in dreams, vivid pictures of objects float 

 before the mind, and are referred by it to the external organ 

 which may be all the time entirely quiescent/ 



"Grainger makes remarks to the same effect. Having 

 spoken of the confusion consequent on the attempt to establish 

 two kinds of sensibility, animal and organic, he says, — ' if we 

 free ourselves for an instant from all these confused notions, it 

 becomes evident that there is but one kind of sensibility ; for 



