18 Mr. Carlisle's Lecture 
adapted to the last weak actions of life, and to its gradual 
recommencement. 
This diminished respiration is the first step into the state of 
torpidity ; a deep sleep accompanies it ; respiration then ceases 
altogether ; the animal temperature is totally destroyed, cold- 
ness and insensibility take place, and finally the heart concludes 
its motions, and the muscles cease to be irritable. It is worthy 
of remark that a confined air, and a confined respiration, ever 
precede these phenomena : the animal retires from the open 
atmosphere, his mouth and nostrils are brought into contact 
with his chest, and enveloped in fur ; the limbs become rigid, 
but the blood never coagulates during the dormant state. On 
being roused, the animal yawns, the respirations are fluttering, 
the heart acts slowly and irregularly, he begins to stretch out 
his limbs, and proceeds in quest of food. During this dor- 
mancy, the animal may be frozen, without the destruction of 
the muscular irritability, and this always happens to the garden 
snail,* and to the chrysalides of many insects during the winter 
of this climate. 
The loss of motion and sensation from the influence of low 
temperature,, accompany each other, and the capillaries of 
the vascular system appear to become contracted by the loss 
of animal heat, as in the examples of numbness from cold. 
Whether the cessation of muscular action be owing to the 
impeded influence of the nerves, or to the lowered temperature 
of the muscles themselves, is doubtful ; but the known in- 
fluence of cold upon the sensorial system, rather favours the 
supposition that a certain temperature is necessary for the 
transmission of nervous influence, as well as sensation. 
* Helix nemoralis . 
