that of the atmosphere, and they do not endure heat or cold, so well as 

 the more perfect animals. 



The lungs, as was before observed, consuming only a certain quantity 

 of air, there is no increase of temperature, however great the quantity 

 of oxygen contained in the atmosphere that is breathed 5 as a man who 

 should take a double quantity of aliment, could not receive more nourish- 

 ment, than if he contented himself with the quantity of food proportion- 

 ed to his wants ; for, as the digestive organs can extract only a certain 

 quantity of chyle, the quantity of recrementitious matter would only be 

 greater, if more than the due quantity of food were received into the 

 stomach. Hence the common saying, that nourishment comes from what 

 we digest, and not from what we eat. 



The pulmonary organ may, however act on the air, with different de- 

 grees of power, 'in robbing it of its oxygen: and when the body becomes 

 of an icy coldness, in certain nervous and convulsive affections, this cold 

 may depend as much on the atony of the lungs, and on the spasmodic 

 condition of the chest, which, dilating with difficulty, does not admit the 

 air readily, as on the spasm and general insensibility of the organs, which 

 allow the blood to pass without affecting its component parts. It would 

 be curious to ascertain, whether the air expired from the lungs of a cata- 

 leptic, contains more oxygen, is less impaired, and contains a smaller 

 quantity of carbonic acid than the breath of a sound active adult. Per- 

 haps it would be found, that in catalepsy and other similar affections, the 

 blood does not part with its hydrogen and carbon, that it retains its co- 

 louring principles, and the different materials of the urine, which is void- 

 ed in a colourless and limpid state, insipid and without smell, and in the 

 condition of a mere serosity. 



The temperature of the body is produced, not only by the pulmonary 

 and circulatory combinations ; it is besides developed in several organs, 

 in which fluid or gaseous substances become solid by parting with a por- 

 tion of their caloric. Thus digestion, particularly of certain kinds of 

 food, is an abundant source of caloric; the skin which is habitually in 

 contact with the atmosphere, decomposes it and deprives it of its caloric. 

 Lastly, caloric is produced and evolved in all parfs, whose molecules 

 affected by a double motion, in consequence of which they are incessantly 

 being formed and decomposed, by changing their condition and consist- 

 ence, absorb or disengage more or less caloric. The great activity of the 

 power of assimilation in children, is, no doubt, the cause of the habitually 

 high temperature, at that period of life. The temperature of the body 

 is not only one or two degrees higher at that period of life; but young 

 people, after death, preserve for a longer period the remains of vital 

 heat; or rather, as tonicity does not so soon forsake the capillary vessels, 

 life departing reluctantly, the combinations from which caloric is evolved, 

 continue some time, even after it is extinct. For the same reason, the 

 bodies of persons that have died suddenly, retain their warmth long, 

 while an icy coldness seizes the bodies of those who have died of linger- 

 ing disease, from the slow, gradual, and total abolition of the powers of 

 life. 



Calorification, or the disengagement of animal heat, like nutrition, takes 

 place at all times and may be considered as belonging to all organs. It 

 was of the utmost consequence, that the internal temperature of the 

 human body should be nearly the same at all times. For, let us, for one 

 moment, suppose that the temperature of the blood should rise to fifty 



