ARTIFICIAL REDUCTION OF BODILY TEMPERATURE IN ANIMALS. 409 



vessels in consequence of the slowness of the current. Thus the circulation at 

 the periphery is slowed. If the intense effect of the freezing be continued the 

 movement of blood at the periphery ceases entirely and principally in the thinnest 

 parts, namely the ears, the nose, the toes and the fingers. The functions of the 

 sensory nerves become impaired, and numbness and anesthesia develop. Later 

 there may be even complete freezing throughout. If the peripheral parts become 

 anemic, the internal organs naturally become hyperemic and the heart is distended 

 with blood. 



As the retardation of the circulation must naturally be transmitted from the 

 surface of the body to the other circulatory areas, increased venosity of the blood 

 develops in consequence of diminished circulation through the lungs, notwith- 

 standing the larger amount of oxygen in the cold, dense air, and as a result the 

 activity of the nerve-centers is affected. Great disinclination to movement, a 

 distressing feeling of fatigue, a peculiar irresistible tendency to sleep, an inability 

 to think logically, uncertainty in sensorial activity, and finally complete loss of 

 consciousness are the symptoms of this condition. At a temperature of 0.56 C. 

 the blood freezes, while the fluids of the superficial portions of the body become 

 rigid somewhat earlier. The protoplasm, as, for instance, of the muscles, may 

 be cooled on careful^ experimentation down to a temperature of 18 C. without 

 becoming solid. In making attempts at resuscitation or at thawing, all bending 

 or breaking movements of the rigid parts is to be avoided, in order that the crystals 

 of ice do not perforate the tissues. Further, too rapid heating is to be avoided, 

 as hereby sudden expansion of the tissues might be brought about, and give rise 

 to their molecular destruction. Simple rubbing with snow in order if possible 

 to set the blood gradually in motion from the parts that are not frozen toward 

 those that are rigid, with gradual warming, will yield the best results. Often 

 complete freezing is followed by partial death of the affected part. 



ARTIFICIAL REDUCTION OF THE BODILY TEMPERATURE IN 



ANIMALS. 



In consequence of reduction of the temperature of the body the 

 activity of the most highly developed nerve-centers (cerebrum) is 

 diminished first and only later that of the medulla oblongata. If "the 

 functions of the latter are beyond restoration death must result. 



Artificial reduction of the temperature in warm-blooded animals by 

 exposure to a cold atmosphere, or to cold-mixtures, is followed by a 

 series of characteristic phenomena. If the temperature of the animals 

 rabbits is lowered to 18 C. rectal temperature they are overcome by 

 great prostration, without abolition, however, of voluntary and reflex 

 movements, although these are lost at a temperature of 17 C. The 

 pulse is reduced in frequency from 100 or 150 to 20 beats in a minute, 

 and at the same time the blood-pressure falls to a few millimeters of 

 mercury. Respirations are infrequent and superficial, and breathing, 

 therefore, becomes inadequate (at 25 C., in rabbits). Asphyxia is no 

 longer capable of exciting convulsions ; the secretion of urine ceases ; and 

 the liver exhibits excessive hyperemia. In this condition the animal 

 may remain for twelve hours; then, after the muscles and the nerves 

 exhibit signs of paralysis, coagulation of the blood has taken place fol- 

 lowing the destruction of large numbers of blood-corpuscles, and the 

 eye-ground has become pale, death takes place amid symptoms of 

 paralysis of the heart, convulsions and asphyxia. 



If left to itself, an animal whose temperature has been reduced to 

 1 8 C. is incapable of recovery when the surrounding temperature is the 

 same. If, however, artificial respiration is practised the bodily tem- 

 perature rises 10. If in conjunction with the latter, heat is in addition 

 supplied from without, the animals recover completely, even when 

 they have been apparently dead for about forty minutes. Walther was 



