One of the most interesting phases of the life history of any animal is its life in the winter when conditions of temperature and food supply are generally very adverse. The fact that some animals have the ability to meet these conditions by hibernating gives them a particular interest to not only the naturalist, but the physiologist and anatomist as well. In recent years a great deal of interest has been given to this field in respect to its surgical application, especially in the field of cardiovascular and cerebral surgery.