456 IIYBERNATION AND USE OF COLD. 



Artificial Cold-Blooded Condition. Cl. Bernard made the important 

 observation, that the muscles of animals that had been cooled remained 

 irritable for a long time, both to direct stimuli as well as to stimuli 

 applied to their nerves ; and the same is the case when the animals are 

 asphyxiated for want of 0. An " artificial cold-blooded condition" i.e., a 

 condition in which warm-blooded animals have a lower temperature, 

 and retain muscular and nervous excitability (Cl. Bernard), may also 

 be caused in warm-blooded animals, by dividing the cervical spinal- 

 cord and keeping up artificial respiration ; further, by moistening the 

 peritoneum with a cool solution of common salt (Wegner). 



Hybernation presents a series of similar phenomena. Valentin found that 

 hybernating animals become half-awake when their bodily temperature is 28C. ; 

 at 18C. they are in a somnolent condition, at 6 they are in a gentle sleep, and 

 at 1 '6C. in a deep sleep. The heart-beats and the blood-pressure fall, the former 

 to 8-10 per minute. The respiratory, urinary, and intestinal movements cease 

 completely, and the cardio -pneumatic movement alone (p. 110) sustains the slight 

 exchange of gases in the lungs. They cannot endure cooling to 0C. ; they awake 

 before the temperature falls so low. Hybernating animals may be cooled to a 

 greater degree than other mammals; they give off heat rapidly, and they become 

 warm again rapidly, and even spontaneously. New-born mammals resemble 

 hybernating animals more closely in this respect than do adults. 



Cold-blooded Animals may be cooled to 0. Even when the blood has been 

 frozen and ice formed in the lymph of the peritoneal cavity, frogs may recover. 

 In this condition they appear to be dead, but when placed in a warm medium 

 they soon recover. A frog's muscle so cooled will contract again (Kiihne). The 

 germs and ova of lower animals, e.g., insects' eggs, survive continued frost; and 

 if the cold be moderate, it merely retards development. Bacteria survive a 

 temperature of 87C.; yeast, even 100 C. (Frisch). 



Varnishing the Skin causes a series of similar phenomena. The varnished 

 skin gives off a large amount of heat by radiation (Krieger), and sometimes the 

 cutaneous vessels are greatly dilated (Laschkewitsch). Hence the animals cool 

 rapidly and die, although the consumption of is not diminished. If cooling be 

 prevented (Valentin, Schiff, Brunton) by warming them and keeping them in 

 warm wool, the animals live for a longer time. The blood post mortem does not 

 contain any poisonous substances, nor even are any materials retained in the blood 

 which can cause death, for if the blood be injected into other animals, these 

 remain healthy. Varnishing the human skin does not seem to be dangerous^ 

 (Senator). 



226. Employment of Cold. 



Cold may be applied to the whole or part of the surface of the body in the 

 following conditions : 



(a) By placing the body for a time in a cold bath to abstract as much heat as 

 possible, when the bodily temperature in fever rises so high as to be dangerous 

 to life. This result is best accomplished and lasts longest when the bath is 

 gradually cooled from a moderate temperature. If the body be placed at once in 

 cold water, the cutaneous vessels contract, the skin becomes bloodless, and thus 

 obstacles are placed in the way of the excretion of heat. A bath gradually cooled 

 in this way is borne longer (v. Ziemssen), The addition of stimulating substances, 



