184 



lus which determines their action, carry on their functions imperfectly^ 

 and at last cease to act. The animal heat is likewise lowered a few de- 

 grees, ab was ascertained by the above mentioned physician, who thinks 

 he has established as a fact, that the ligature of the nerves of the lungs 

 does not destroy but weakens the Vital power, which enables them to take 

 up the oxygen, and to give out the carbonic acid. The brain, therefore, 

 possesses a double influence over the function of respiration; on the one 

 hand, it directs its mechanism, by means of the nerves which it sends to 

 the diaphragm, and to the intercostal muscles, and on the other hand, it 

 is through the nerves which arise from the brain, that the lungs have the 

 power of converting dark blood into arterial blood, which is the principal 

 phenomenon of respiration. 



Experiments performed on the same subject, by Dr. Le Gallois, subse- 

 quent to those I just related, tend to throw some degree of uncertainty 

 on their results. Dr. Le Gallois repeated these experiments publicly, in 

 my presence, and at the society of the Medical School of Paris. After 

 dividing the two nerves of the eighth pair, in a guinea-pig, and after hav- 

 ing, by that process, brought on a state of usphyxia, he restored life and 

 motion to the animal, by opening the trachea at its interior part. The 

 blood of the carotids, which from red had become dark the moment the 

 nerves were divided, respiration is restored, and the animal lives seve- 

 ral days after the experiment. Whence does this difference arise ? does 

 the division of the eigth pair bring on asphyxia, by occasioning a spas- 

 modic constriction of the glottis, and by impeding, or even completely 

 obstructing the admission of the atmospherical air*? 



LXXVIII. Of animal heat. The human body, which is habitually of 

 a temperature of between thirty-two and thirty-four degrees of Reau- 

 mur's thermometerf, preserves the same degree of warmth under the 

 frozen climate of the polar region, as well as under the burning atmos- 

 phere of the torrid zone, during the most severe winters and the hottest 

 summers. Nay, further, the experiments of Blagden and Fordyce in 

 England, and of Duhamel and Tillet in France, show, that the human 

 body is capable of enduring a degree of heat sufficient to bake animal sub- 

 stances. The fellows of the Academy of Sciences, saw two girls enter 

 into an oven, in which fruits and animal substances, were being baked ; 

 Reaumur's thermometer, which they took in with them, stood at 150 de- 

 grees; they remained several minutes in the oven, without suffering any 

 inconvenience. 



All living bodies have a temperature peculiar to themselves, and inde- 

 pendent of that of the atmosphere. The sap of plants does not freeze, 

 when the thermometer stands only at a few degrees above zero; on placing 

 the bulb of a thermometer in a hole in the trunk of a tree, during winter, 

 the fluid sensibly rises. Now, three circumstances remain to be inves- 

 tigated : in the first place, what produces in living bodies, this inherent 

 and independent temperature ? In the second place, how do these bodies 

 resist the admission of a greater degree of heat, than that which is natu- 

 ral to them ? What prevents caloric, which has a perpetual tendency to a 

 state of equilibrium, from passing into a body surrounded by a burning 

 atmosphere? Lastly, how does a body which resists the influence of heat, 



* See APPENDIX, Note W. 



f Between 96 and 98 of Fahrenheit. 



