342 CRUSTACEA. 



brain, and the sole correspondents with the instruments of the 

 higher senses, are alone capable of appreciating sensations of a 

 painful character. Thus, then, we arrive at a very important con- 

 clusion, namely, that the perception of pain depends upon the 

 developement of the encephalic masses ; and consequently, that, as 

 this part of the nervous system becomes more perfect, the power 

 of feeling painful impressions increases in the same ratio : or, 

 in other words, that, inasmuch as the strength, activity, and intel- 

 ligence of an animal, by which it can escape from pain, depends 

 upon the perfection of the brain, so does the perception of torture 

 depend upon the condition of the same organ. How far the feel- 

 ing of pain is acutely developed in the animals we are now consi- 

 dering is deducible from every-day observation. The fly seized 

 by the leg will leave its limb behind, and alight with apparent 

 unconcern to regale upon the nearest sweets within^ its reach : 

 the caterpillar enjoys, to all appearance, a tranquil existence 

 while the larvae of the Ichneumon, hatched in its body, devour its 

 very viscera : and in the Crustacea before us, of so little import- 

 ance is the loss of a leg, that the lobster will throw off its claws 

 if alarmed by the report of a cannon. 



(377.) The singular power of breaking off their own limbs, 

 alluded to in the last paragraph, is possessed by many Crustacea, 

 and is a very indispensable provision in their economy. We have 

 already found the blood-vessels of these animals to be of a delicate 

 structure ; and, the veins being wide sinuses whose walls possess 

 little contractility, the fracture of a limb would inevitably produce 

 an abundant and speedily fatal haemorrhage was there not some con- 

 trivance to remedy the otherwise unavoidable results of such a catas- 

 trophe. Should the claw of a lobster, for example, be accidentally 

 damaged by accidents to which creatures encased in such brittle 

 armour must be perpetually exposed, the animal at once breaks 

 off the injured member at a particular part, namely, at a point 

 in the second piece from the body ; and by this operation, which 

 seems to produce no pain, the bleeding is effectually staunched. 



But the most remarkable part of the phenomenon remains to be 

 noticed : after this extraordinary amputation has been effected, 

 another leg begins to sprout from the stump, which soon grows to 

 be an efficient substitute for the lost extremity, and gradually, 

 though slowly, acquires the pristine form and dimensions of its pre- 

 decessor. A beautiful example of this curious mode of reprodu- 

 cing a lost organ is preserved in the Museum of Comparative Ana- 



