LIFE HISTORY OF THE BLUE CRAB. 413 



plete. The crab i.s now known as a "soft-shell," and from the eesthetic 

 standpoint is at the height of its glory, for all the brilliant coloration 

 of the various parts is undinimed by an}^ of the shell deposits, the soft 

 integnment seeming- to bear the bright pigments at the very surface. 

 Under natural conditions the crab usually selects some place of con- 

 cealment in which to pass the period of shedding and probably does 

 not leave it until the hew shell has hardened, but it is by no means 

 helpless, even immediately after ecd3'sis has occurred. On the tips of 

 legs which seem too soft to support any weight whatever it can walk 

 awa}^, or, if forced to make the effort, can swim. The new shell 

 hardens quickly. Within twelve hours it becomes parchment-like and 

 the crab is called a "buckler," "buckram," or a "bucklum;" in two 

 or three days it is as hard as ever and once more starts out in search 

 of food." 



AUTOTOMY. 



Autotomy, or the automatic throwing off of the appendages, is very 

 characteristically shown in the blue crab and is of frequent occurrence. 

 Very often if a large individual, in the hard-shelled condition, is cap- 

 tured and held by one leg it will snap the limb off and make its escape. 

 Likewise, if one of the legs is injured toward the tip the entire mem- 

 ber will be dropped off. The breakage always occurs at the same 

 point — across one of the segments near the base of the leg — and is a 

 provision of nature to prevent the animal from bleeding to death. It 

 is practiced ordinarily only by the hard-shelled crabs; an injury to a 

 soft-shelled individual usually causes death. Under other conditions, 

 however — notabl}^, a sudden lowering of temperature — the act has been 

 observed, and in one of the early attempts to procure soft crabs for 

 market, b}^ confining the hard crabs in an inclosure until they had shed 

 their shells, severe cold weather reduced the entire catch to a lot of 

 legless bodies ("buffaloes," they are called by the fishermen). 



Autotomy seems to be limited to the legs, for, so far as I have been 

 able to determine, none of the other appendages are ever thrown off, 

 although if they are forcibly removed they will be regenerated. 



Regeneration of the parts cast off' usually follows autotomy, but, 

 according to the researches of several biologists, will not take place 

 indefinitel}". Three or four times seems to be the limit. The process 

 of regeneration is quite rapid. At the first molt after a limb has been 

 cast off, provided that the injury does not occur inmiediatelj' before a 

 molt, the new limb appears as a small bud in which all the missing 

 segments mav be found, coiled in an elongate spiral. At the next 

 molt the segments straighten out and the new limb, except for its 

 smaller size, looks like the one which was cast off. Another molt, 

 possibly two, will be sufiicient to restore the limb to its full size. 



« It is believed by the fishermen that the molting of the crabs is influenced largely 

 by the moon and the tides, but the evidence to support this theory is very contra- 

 dictory. 



