Volume 1

The works of John Hunter / edited by James F. Palmer.

Date:
1835-37
Catalogue details

Licence: Public Domain Mark

Credit: The works of John Hunter / edited by James F. Palmer. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    therefore a further provision of Nature for enabling animals to support great heat. In order to keep up a just balance of temperature, it is pro- bable that the living powers exert greater effort as evaporation is defi- cient, and less effort as evaporation increases. In emergencies, evapo- ration is not sufficient: when a greater power of producing cold than ordinary is required, the powers of the animal are called forth. As animals can only destroy a certain quantity of heat in a given time, so the time they can continue the full exertion of this destroying power seems also limited. It is probable that both the power of destroying heat, and the time in which that power can be exerted, may be increased by frequent exercise. When Dr. Fordyce was in the heated room, his hand became so hot as to make his body feel cool to it*. It is probable that that part, from its habit of changing its degree of heat, is more ready to take on differ- ent degrees of heat applied. It is found from experiment, in the appli- cation of cold, that all the extremities are more subject to the laws of inanimate matter than the body; and the nearer the source of circula- tion, the greater the deviation is from these laws. Possibly the same may be observed with regard to heat. In animals which have a standard heat it would appear to be more natural to form than to destroy heat, (although the power of destroying it appears to be much greater than that of producing it,) for we may observe that they live with much more ease to themselves when in an atmosphere considerably lower than their standard, in which they must constantly be generating heat, than in an atmosphere even of their own temperature, in which it cannot be necessary for them to form heat; so that either this action simply of generating heat, or being in such a degree of cold as makes this action necessary, proves salutary to the constitution f. Perhaps the medium between their extreme heat, which is 98°, and the lowest degree they can come to, is the proper and most wholesome temperature of the atmosphere, and this is about 63°. Some of these animals which are endowed with this property of a standard heat have this power of generating heat much stronger than others, and are always best in those situations where this power can be exercised : we should naturally suppose that this power always requires a necessity for that exertion equal to its power, so that the power and the necessity should always be proportioned. This cannot he the case * [This effect probably arose from the superior denseness of the cuticular covering of the hand preventing perspiration.] f [It is certainly a remarkable proof of Hunter’s penetrating sagacity that he should have been able to arrive at so general a truth without being acquainted with the true cause of animal heat, or the intimate connexion which subsists between this function and that of respiration. (Sec Treatise on Inflammation, loc. cit.)]