EFFECTS OF EXTREME COLD. 877 



ably true of Man, a greater range of temperature, in disease, having 

 been observed previous to death, in the descending than in the ascend- 

 ing scale of warmth. The relative degrees of external heat and cold, 

 which are endurable by Man, with proper precautions, in the different 

 climates of the world, also prove that he can sustain, without injury, 

 a greater diminution than an elevation of the external temperature. 

 In the Arctic regions the thermometer has been recorded at tempera- 

 tures as low as from 55 to 70, the latter temperature being no 

 less than 170 below the normal temperature of the blood ; whilst, in 

 the other direction, the highest temperature registered in the tropics 

 is about 130 in the shade, viz., about 30 above the blood heat. Man 

 is much more readily inured to cold than to heat; and the inhabitants 

 of temperate regions, when they remove to the tropics, require to be 

 more specially acclimatized, and can scarcely avoid becoming ill ; 

 whilst, in removing to colder latitudes, with due precautions, health 

 may be more easily preserved. Nevertheless, cold, to the feeble and 

 aged, is the great enemy of animal life, and the chief remote cause of 

 human mortality. 



When the living human body is exposed to the prolonged action of 

 extreme cold, without protection, a gradual benumbing of the sensi- 

 bility, a lowering of the circulation and respiration, and a general tor- 

 pidity of the system, are produced. These effects occur more readily 

 in children, and in infirm, ill-fed, or starved persons, and also in aged 

 persons ; and lastly, in those who are previously overcome by fatigue, 

 or by the narcotic effects of alcohol. The nervous system is specially 

 subjected to the influence of cold; the senses frequently act irregularly, 

 giving rise to noises in the ears, and spectral visions; delirium often 

 supervenes, and, finally, an irresistible tendency to, and desire for 

 sleep, takes complete possession of the frame. Further exposure to 

 cold, then produces a fatal coma. Isolated examples of death from 

 this cause happen in the experience of civilized life; but large num- 

 bers of troops, and even entire armies, especially when ill-fed, clad, 

 and protected, have been lost from the injurious effects of extreme 

 cold. The effect of cold is most marked when the body itself is 

 motionless. Its evil or fatal effects occur more rapidly, however, 

 when the atmosphere itself is in motion ; because, then, fresh quanti- 

 ties of cold air are brought continually in contact with the body, and 

 so conduct away its heat more rapidly. A moist atmosphere is also 

 detrimental, on account of its being a better conductor than dry air. 



The local effects of extreme cold are usually manifested, first upon 

 parts unprotected by covering, or most distant from the centre of the 

 body, such as the feet, hands, face, or ears, and especially the nose. 

 In such case the skin first becomes red from congestion of the dilated 

 small arteries and capillaries, next it becomes blue from arrest of the 

 circulation, and afterwards of a tallowy white, from the extreme con- 

 striction of the arteries supplying the part, so that the circulation is 

 first retarded and then entirely arrested. In perfect congelation 

 minute particles of ice actually form in the tissues. The congealed 

 tissues may sometimes be restored to their normal state, provided that 

 the return to a higher temperature be gradual, as is often and best ac- 



