Crustacea. 



6625 



muscular contraction at the joint second from the body of the animal; 

 it is then struck against some foreign substance, and belongs no more 

 to the creature. Simultaneous with this operation, a thin membrane 

 of chitine is generated upon the surface, and it is not impossible that 

 this may be the amputating means. The entire act is one of a few 

 seconds only, except when they have but recentty cast the old shell ; 

 while the new one is soft and yielding it will remain attached some- 

 times for half an hour, but this attachment I presume to be merely me- 

 chanical, the organic union having been, internally, previously severed. 



In carrying out these experiments I once cut the claw of a crab so 

 as to remove only part of the thumb and finger. The limb was not 

 rejected, and when the shell was cast the hand continued maimed, 

 and never was reproduced. I well remember that immediately after 

 the injury the poor thing raised up its wounded arm and fled from 

 the scene of danger; and when it had gone as far as the prison would 

 permit, it with the other hand cautiously felt the wound ; and then 

 repeatedly, for some time, gently stroked the arm between the fingers 

 of the claw, and, as much as it was possible to express pain, showed 

 that it was suffering. It is easy to say, and perhaps demonstrable 

 theoretically, that the nerves which give an expression of agony are 

 not those which convey the sensation of pain ; but a reflex action 

 seldom occurs in ourselves without a previous sensation of pain. 



Philosophy teaches us that pain is no evil, — that it is sent as 

 a monitor to instruct us as to the health or disease of any part of the 

 body. But surely it would be unphilosophical to teach that the same 

 law holds not its place in relation to the lower forms of animal life, 

 because they are less dependent upon external curative treatment ; 

 and certainly the fact of the self-amputation of a limb, because it is 

 wounded, is evidence of the value of pain, since it is an operation 

 that we could never suppose any animal to perform unless it instinc- 

 tively felt that it would remove a greater evil, just as is the case in 

 man when he extracts a tooth to relieve himself of a severer pain. 



As before remarked, the arguments which are made use of to prove 

 the animal cannot suffer pain must also have force in relation to the 

 senses. Pain is no independent sense : it is only a modification of 

 touch, in the same way as acute hearing amounts to suffering; and 

 no one doubts that these animals can see, hear and smell, and that 

 they have especial organs for the purpose. 



The sense of sight may not be as definite in the Articulata as it is 

 in man, but there is every external evidence to demonstrate that the 

 organ of vision is perfect in its adaptation, and as perfect in its 

 xvil. 2 s 



