338 . ARTIFICIAL LOWERING OF THE TEMPERATURE. 



causing reflexly a more rapid molecular transformation, and therefore a greater 

 production of heat, while the amount of heat given off is diminished owing to con- 

 traction of the small cutaneous vessels and the skin itself (Liebermeister). The 

 continuous and Intense application of cold causes a decrease of the temperature, 

 chiefly by conduction, notwithstanding that at the same time there is a greater 

 production of heat. After a cold bath the temperature may be 34, 32, and even 

 30 C. 



As an after-effect of the great abstraction of heat, the temperature of the body 

 after a time remains lower than it was before ("primary after-effect" Lieber- 

 meister)-, thus after an hour it was 0*22 C. in the rectum. There is a "secondary 

 after-effect " which occurs after the first after-effect is over, when the temperature 

 rises (Jiirgensen). This effect begins five to eight hours after a cold bath, and is 

 equal to +0*2 C. in the rectum. Hoppe-Seyler found that some time after the 

 application of heat there was a corresponding lowering of the temperature. 



Taking Cold. If a rabbit be taken from a surrounding temperature of 35 C, and suddenly 

 cooled, it shivers, and there may be diarrhoea. After two days the temperature rises 1*5 C, 

 and albuminuria occurs. There are microscopic traces of interstitial inflammation in the 

 kidneys, liver, lungs, heart, and nerve-sheaths, the dilated arteries of the liver and lung con- 

 tain thrombi, and in the neighbourhood of the veins are accumulations of leucocytes. In preg- 

 nant animals the fcetus shows the same conditions. Perhaps the greatly cooled blood acts as an 

 irritant causing inflammation. 



Action of Frost. The continued application of a high degree of cold causes at first contrac- 

 tion of the blood-vessels of the skin and its muscles, so that it becomes pale. If continued 

 paralysis of the cutaneous vessels occurs, the skin becomes red owing to congestion of its 

 vessels. As the passage of fluids through the capillaries is rendered more difficult by the cold, 

 the blood stagnates, and the skin assumes a livid appearance, as the is almost completely 

 used up. Thus the peripheral circulation is slowed. If the action of the cold be still more 

 intense, the peripheral circulation stops completely, especially in the thinnest and most exposed 

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

 ness with 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 circu- 

 lation, the pulmonary circulation is enfeebled, and diminished oxidation of the blood occurs, 

 notwithstanding the greater amount of 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 '9 C. , while the juices of the superficial 



Earts freeze sooner. Too rapid movements of the frost-bitten parts ought to be avoided. Rub- 

 ing with snow, and the very gradual application of heat, produce the best results. Partial 

 death of a part is not unfrequently produced by the prolonged action of cold. 



225. ARTIFICIAL LOWERING OF THE TEMPERATURE. 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. 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, the secretion of urine stops, and the liver is 

 congested. The animal may remain for twelve 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. 

 An animal cooled to 18 C, and left to itself, at the same temperature as the sur- 

 roundings, does not recover of itself, but if artificial respiration be employed, the 

 temperature rises 10 C. If this be combined with the application of external 

 warmth, fine animals may recover completely, even when they have been apparently 

 dead for forty minutes. Walther cooled adult animals to 9 C, and recovered them 

 by artificial respiration and external warmth ; while Horvath cooled young animals 



