302 THE ZOOLOGIST. 



The first is an active ^physiological 'process on the part of the 

 serpent, as the result of which the external covering is separated 

 from the true skin. Prof. Packard describes this separation as 

 being due to the growth of fine temporary cuticular hairs. Thus 

 loosened, the slough rapidly becomes dry, and is ready to be cast 

 off. The second stage, or the casting off, is a mechanical procesSi 

 by which the serpent endeavours to rid itself of what is now no 

 longer a part of its anatomy. This is effected by continuous rub- 

 bing against any convenient surface, the side of the cage in the 

 case of captive snakes. The result of this rubbing, as far as the 

 slough is concerned, depends, in my opinion, on the simple 

 factor of whether the serpent is in a position to rub off both 

 sides of the slough evenly — that is to say, if the reptile can get 

 pressure evenly exerted on both sides of the body — by creeping 

 through grass, or in some other way — the slough will peel off 

 whole, being turned inside out in the process ; but if, on the 

 other hand, any projecting point should come in contact with 

 one side of the slough, the latter, being very delicate, will be 

 torn, and the slough cast in pieces. In very young, and there- 

 fore small snakes, the slough comes off very readily, and gener- 

 ally entire ; but in older and larger specimens I have found it 

 the exception rather than the rule for this to occur, and the 

 slough is usually in pieces. This is quite independent of the 

 state of health of the snake, a matter which is, moreover, some- 

 what difficult of diagnosis, unless the reptile is suffering from 

 canker. I have made a point of observing this sloughing in 

 reptiles in various zoological collections, and invariably have 

 seen the sloughs of the larger serpents in pieces in the cages. 

 Anyone can observe it at the Zoo. It is particularly noticeable 

 in the Pythons ; and I now append a series of notes made by 

 Mr. W. J. Clarke, of Scarborough, on the frequency and 

 character of the sloughings of one of his Pythons : — 



Python moliirus. — Sloughing in confinement (W. J. Clarke, 

 Scarborough). 



" I received the Python on Sept. 7th, 1897. Three weeks 

 later I found one morning that it had shed its slough, but, not 

 expecting this, made no notes. Python now measured Gg- ft. 



" 1. On Nov. 20th, 1897, at 7 p.m.. Python entered the water 

 in its zinc bath. Remained there continuously till 11 p.m. on 



