No. 8. 



Animal Heat. 



253 



Animal Heat. 



(Concluded from p. 2-28, last Number.) 



In cold and temperate climates, the air, 

 which incessantly strives to consume the 

 body, urges man to laborious efforts in order 

 to furnish the means of resistance to its ac- 

 tion, while, in hot climates, the necessity of 

 labour to provide food is far less urgent. 



Our clothing is merely an equivalent for 

 a certain amount of food. The more warmly 

 we are clothed, the less urgent becomes the 

 appetite for food, because the loss of heat 

 by cooling, and consequently the amount of 

 heat to be supplied by the food, is dimin- 

 ished. 



If we were to go naked, like certain sav- 

 age tribes, or if in hunting or fishing we 

 were exposed to the same degree of cold as 

 the Samoyedes, we should be able with ease 

 to consume ten pounds of flesh, and perhaps 

 a dozen of tallow candles into the bargain, 

 daily, as warmly clad travellers have re- 

 lated with astonishment of these people. 

 We should then also be able to take the 

 same quantity of brandy or train oil without 

 bad effects, because the carbon and hydro- 

 gen of these substances would only suffice 

 to keep up the equilibrium between tlie ex- 

 ternal temperature and that of our bodies. 



According to the preceding expositions, 

 the quantity of food is regulated by the 

 number of respirations, by the temperature 

 of the air, and by the amount of heat given 

 off to the surrounding medium. 



No isolated fact, apparently opposed to 

 this statement, can affect the truth of this 

 natural law. Without temporary or perma- 

 nent injury to health, the Neapolitan cannot 

 take more carbon and hydrogen in the shape 

 of food than he expires as carbonic acid and 

 water; and the Esquimaux cannot expire 

 more carbon and hydrogen than he takes 

 into the system as food, unless in a state of 

 disease or of starvation. Let us examine 

 these states a little more closely. 



The Englishman in Jamaica, perceives 

 with regret, the disappearance of his appe- 

 tite, previously a source of frequently recur- 

 ring enjoyment ; and he succeeds, by the 

 use of cayenne pepper and the most power 

 ful stimulants, in enabling himself to take 

 as much food as he was accustomed to eat 

 at home. But the whole of the carbon thus 

 introduced into the system is not consumed; 

 the temperature of the air is too high, and 

 the oppressive heat does not allow him to 

 increase the number of respirations by ac- 

 tive exercise, and thus to proportion the 

 waste to the amount of food taken ; disease 

 of some kind, therefore, ensues. 



On the other hand, England sends her 



sick to southern regions, where the amount 

 of the oxygen inspired is diminished in a 

 very large proportion. Those whose dis- 

 eased digestive organs have in a greater or 

 less degree lost the power of bringing the 

 food into the state best adapted for oxidation, 

 and therefore are less able to resist the oxid- 

 izing influence of the atmosphere of their 

 native climate, obtain a great improvement 

 in health. The diseased organs of digestion 

 have power to place the diminished amount 

 of food in equilibrium with tlie inspired oxy- 

 gen, in the mild climate; while in a colder 

 reo-ion the organs of respiration Ifiemselves 

 would have been consumed in furnishing the 

 necessary resistance to the action of the at- 

 mospheric oxygen. 



In our climate, hepatic diseases, 6x those 

 arising from excess of carbon, prevail in 

 summer; in winter, pulmonary diseases, or 

 those arising from excess of oxygen, are 

 more frequent. 



The cooling of the body, by whatever 

 cause it may be produced, increases the 

 amount of food necessary. The mere ex- 

 posure to the open air, in a carriage or on 

 the deck of a ship, by increasing radiation 

 and vaporization, increases the loss of heat, 

 and compels us to eat more than usual. 

 The same is true of those who are accus- 

 tomed to drink large quantities of cold wa- 

 ter, which is given off at the temperature 

 of the body, 98.5 degrees. It increases the 

 appetite, and persons of weak constitution 

 find it necessary, by continued exercise, to 

 supply to the system the oxygen required 

 to restore the heat abstracted by the cold 

 water. Loud and long continued speaking, 

 the crying of infants, moist air, all exert a 

 decided and appreciable influence on the 

 amount of food which is taken. 



We have assumed that it is especially 

 carbon and hydrogen which, by combining 

 with oxygen, serve to produce animal heat. 

 In fact, observation proves that the hydrogen 

 of the food plays a not less important part 

 than the carbon. 



The whole process of respiration appears 

 most clearly developed, when we consider 

 the state of a man, or other animal, totally 

 deprived of food. 



The first effect of starvation is the dis- 

 appearance of fat, and this fat cannot be 

 traced either in the urine or in the scanty 

 fffices. Its carbon and hydrogen have been 

 given off through the skin and lungs, in the 

 form of oxidized products; it is obvious that 

 they have served to support respiration. 



In the case of a starving man, 32^ ounces 

 of oxygen enter the system daily, and are 

 given out again in combination with a part 

 of his body. Currie mentions the case of 



