36 THE XATUKAL HISTORY OF THE COMMON CRAYFISH. 



that the carapace is raised, nothing stops the crayfish 

 from continuing its struggles. If taken out of the water 

 in this condition, tliey go on moulting in the hand, and 

 even pressure on their bodies will not arrest their efforts. 



The length of time occupied from the first giving way 

 of the integuments to the final emergence of the animal, 

 varies with its vigour, and the conditions under which it 

 is placed, from ten minutes to several hours. The 

 chitinous lining of the stomach, with its teeth, and the 

 " crabs'-eyes," are shed along with the rest of the cuti- 

 cular exoskeleton ; but they are broken up and dissolved 

 in the stomach. 



The new integuments of tlie crayfish remain soft for 

 a period which varies from one to three days ; and it is 

 a curious fact, that the animal appears to be quite aware 

 of its helplessness, and governs itself accordingly. 



An observant naturalist says : " I once had a do- 

 mesticated crayfish {Astacus fluviatilis), which I kept in 

 a glass pan, in water, not more than an inch and a half 

 deep, previous experiment having shown that in deeper 

 water, probably from want of sufficient aeration, this 

 animal would not live long. By degrees my prisoner 

 became very bold, and when I held my fingers at the 

 edge of the vessel, he assailed them with promptness and 

 energy. About a year after I had him, I perceived, as I 

 thought, a second crayfish with him. On examination, 

 I found it to be his old coat, which he had left in a most 

 perfect state. My friend had now lost his heroism, and 



