IWIBERNATION AND SLOUGHING, 65 
nating in aiass. The second incident mentioned by 
my correspondent does not refer to hibernation, but 
simply to the fact that adders do swarm together. 
The physiological condition of a snake when hiber- 
nating is very remarkable. Ltespiration is almost sus- 
pended, but the heart goes on beating feebly and 
irregularly. Digestion is totally stopped, and the 
temperature of the reptile sinks to that of its sur- 
roundings—that is, to the temperature of the protected 
crevice, hole, or heap of leaves, not the temperature of 
the atmosphere above. If at this stage the snake be 
disturbed and roused, death usually results. Extreme 
cold wakes them sometimes, and being unable to per- 
form their vital processes with sufficient activity at 
that temperature, they die. No doubt many of our 
reptiles perish every year from cold in the winter. 
It is a somewhat common belief, and one which 
is found in many books, that the bite of venomous 
serpents, if sustained when the reptile is roused during 
its period of hibernation, is comparatively harmless ; 
and conversely, that the hotter the season the more 
virulent is the poison, This point was made the sub- 
ject of observation by Dr Guyon, who comes to a 
somewhat different conclusion. As the result of his 
investigations, he is of opinion that the matter of 
scason or external temperature is not the most important 
factor in determiniug the degree of virulence of the 
poison. He finds that the most poisonous bite is that 
from a poison-gland which has been accumulating its 
i 
