Insects. 4581 



as the " perception of the organs of sense," which are so constituted 

 as to inform their possessor of the contact or proximity of external 

 objects, and the perceptions so excited may be either pleasurable or 

 the contrary — i.e. may produce either pleasure or pain. 



As to the degree in which these sensations are felt by animals 

 other than man we can have no direct evidence, and can therefore 

 only reason on thern by analogy : thus, we find that certain inflictions 

 produce certain effects on man; the like inflictions produce pretty 

 similar results on all animals possessing a warm-blooded nervous 

 organization similar to man, and as we are assured by man that such 

 inflictions on him are accompanied by certain peculiar unpleasant 

 sensations, i. e. by pain, I think we may not unreasonably conclude 

 that such sensations, differently modified in some cases by other 

 principles intervening, are also the results of the like inflictions 

 on those similarly constituted animals. I am aware that this is but a 

 presumption in favour of all warm-blooded animals possessing the 

 same corporeal feelings; but it is still a fair presumption, although 

 we know that many similar injuries do occasionally produce very 

 different degrees of pain, even on different individuals of our own 

 species, and, therefore, as we cannot infallibly deduce any particular 

 amount of pain from any particular injury on one species of a large 

 class, still less can we do so in reference to all the species of that 

 class : however, the general truth of the proposition will, I think, be 

 granted. 



Passing on, then, to animals of a very different organization, still 

 nervous but with a circulation of cold fluids, such as reptiles and 

 fishes, we find that similar inflictions produce on them by no means 

 the same results as on warm-blooded animals : a tortoise has been 

 known to live four months after deprived of its brain, and without 

 showing any symptom of suffering (see Dalzell's Introduction to 

 translation of Spallanzemi, p. 45). " Neither are insects or worms, 

 likewise of a cold circulation, affected by injuries in anything like 

 the degree that warm-blooded animals are : thus, once when out 

 walking I had captured one of the largest species of dragon-fly, and 

 after nipping the thorax pretty sharply, and apparently killing it, I 

 pinned it to my walking-stick with a pin, the size of which, compared 

 with the present entomological pins, was quite a lark-spit; however, 

 after carrying it in this way for about half an hour, it began to flutter 

 as violently as if totally uninjured, and disengaging itself from the 

 stick, flew straight away, pin and all, at a considerable height in the 

 air, until I lost sight of it in the distance. More recently I had taken 

 XIII. H 



