ARTIFICIAL LOWERING OF THE TEMPERATURE. 455 



ears, nose, toes, and fingers. The sensory nerves are paralysed, so that there is 

 numbness and loss of sensibility, and the parts may even be frozen through and 

 through. As the slowing of the circulation in the superficial vessels gradually 

 affects other areas of the circulation, the pulmonary circulation is enfeebled, and 

 diminished oxidation of the blood occurs, notwithstanding the greater amount of 

 O in the cold air, so that the nerve centres are affected. Hence, arise great dislike 

 to making movements or any muscular effort, a painful sensation of fatigue, a 

 peculiar and almost irresistible desire to sleep, cerebral inactivity, blunting of 

 the sense-organs, and lastly, coma. The blood freezes at 3'9C., while the juices 

 of the superficial parts freeze sooner. Too rapid movements of the frost-bitten 

 parts ought to be avoided. Rubbing with snow, and the very gradual application 

 of heat, produce the best results. Partial death of a part is not un frequently 

 produced by the prolonged action of cold. 



225. Artificial Lowering of the Temperature 



in Animals, 



Phenomena. The artificial cooling of warm-blooded animals, by 

 placing them in cold air or in a freezing mixture gives rise to a series 

 of characteristic phenomena (A. Walther). If the animals (rabbits) 

 are cooled so that the temperature (rectum) falls to 18, they suffer 

 great depression without, however, the voluntary or reflex movements 

 being abolished. The pulse falls from 100 or 150 to 20 beats per 

 minute, and the blood-pressure falls to several millimetres of Hg. The 

 respirations are few and shallow. Suffocation does not cause spasms 

 (Howarth), the secretion of urine stops, and the liver is congested. 

 The animal may remain for 12 hours in this condition, and when the 

 muscles and nerves show signs of paralysis, coagulation of the blood 

 occurs after numerous blood-corpuscles have been destroyed. The 

 retina becomes pale, and death occurs with spasms and the signs of 

 asphyxia. 



If the bodily temperature be reduced to 17 and under, the 

 voluntary movements cease before the reflex acts (Kichet and 

 Rondeau). 



An animal cooled to 18C., and left to itself, at the same temperature 

 of the surroundings, does not recover of itself, but if artificial respira- 

 tion be employed, the temperature rises 10C. If this be combined 

 with the application of external warmth, the animals may recover com- 

 pletely, even when they have been apparently dead for forty minutes. 

 Walther cooled adult animals to 9C., and recovered them by artificial 

 respiration and external warmth; while Howarth cooled young 

 animals to 5C. Mammals, which are born blind, and birds, which 

 come out of the egg devoid of feathers, cool more rapidly than others. 

 Morphia, and more so, alcohol, accelerate the cooling of mammals; hence, 

 drunk men are more liable to die when exposed to cold. 



