HIBERNATION AND SLOUGHINCx. 73 



on what the reptile happens to rub itself against in its 

 effort to rid itself of what has become an incubus. 

 Should the adder happen to find itself evenly wedged 

 in between two stones, or to have equable pressure 

 exerted upon its sides in crawling through a thick 

 bush, then the slough will peel off entire. But the 

 slough is a most fragile and delicate substance, ex- 

 tremely easily torn, and it must very frequently 

 happen that at one stage or other of the shedding 

 a portion will be ruptured by catching against some 

 contiguous thorn or stone or bramble. When this 

 takes place the resulting slough will not be in one 

 piece but in sections. I have captured a large number 

 of adders while they were sloughing, and in nine out 

 of ten cases the slough was torn partially off before 

 the process was completed. I think this a very usual 

 occurrence, quite apart from the healthy condition or 

 otherwise of the adder. Adders cast their sloughs, 

 as a rule, at least three times every summer, and 1 

 have observed that the female is very often under- 

 going the change of cuticle just before the birth of 

 .her young. The tail slough comes off very easily, and 

 is not turned inside out, as a rule, though it frequently 

 is in males. I have on several occasions, after taking 

 an adder that was sloughing, tried to complete the 

 process as one would skin an eel, and on each occasion 

 part of the slough came off in my hand, proving how 

 slight a force is sufticient to tear it in pieces. More- 

 over, though I have frequently found pieces of adder 



