ANIMAL KEAT. 243 



respiration artificially. The usual chemical changes of the blood 

 continued in the lungs ; yet the temperature of the animals 

 diminished, and even more rapidly than if the respiration had not 

 been continued, owing, it is said, to the succession of cool air 

 sent into the lungs. He therefore concludes that animal heat 

 depends much more upon the nervous energy than upon the 

 chemical changes of the blood. x But this experiment proves 

 nothing ; because Dr. Le Gallois asserts that, under artificial re- 

 spiration the temperature may fall, and the animal actually be 

 killed by cold, even though every part remain uninjured. y In 

 artificial respiration the air does not rush into the pulmonary 

 cells, because these are in a vacuum ; but is propelled into, and 

 forcibly, and therefore injuriously, dilates them : the consequence 

 is, the formation of a large quantity of frothy mucus. Whether 

 the fall of temperature be owing to the evaporation of this 

 copious secretion and its prevention of contact between the air 

 and air-cells, or to the injurious nature of artificial respiration, still 

 the fact ascertained by Le Gallois destroys the conclusion which 

 appeared deducible from Sir B. Brodie's experiment. Indeed, 

 Le Gallois found that less oxygen was consumed than in natural 

 breathing, and that the temperature fell exactly in proportion to 

 thesmallness of the quantity of oxygen consumed. Dr. Crawford 

 himself stated that the chemical process of respiration may, in 

 certain cases, be the means of cooling the body. If the pulmonary 

 exhalation, he said, is in very great abundance, it will carry off so 

 much of the heat, given out during the change of the oxygen into 

 carbonic acid, that there may not be sufficient to saturate the 

 increased capacity of the arterial blood: this, therefore, will ab- 

 sorb caloric from the system, as it passes along, till its tem- 

 perature equals that of all parts. 2 I may here remark, that the 



x Phil. Trans. 1812. y Experiences sur le Principe de la Vie. 



z On Animal Heat, p. 388. Instances are recorded by Morgagni (iv. xlix. 26.), 

 and De Haen (Ratio Medendi, vol. iii. p. 36.), in the German Ephemerides 

 (Dec. ii. Ann. iv.), and by Mr. Thackrah, of the blood which streamed down the 

 extremity in venesection feeling cold to the patient and the practitioner. One 

 woman compared it to ice ; and the sensation given to Mr. Thackrah was the 

 same as that of water at 68. (Thackrah, On the Blood, p. 87.) In the Ephe- 

 merides the same is recorded of blood from the nose. The stomach of a cod was 

 found by Dr. Mosely to be not only colder than the water from which it was 

 taken, and the rest of the fish, but painfully to benumb the hand. (Diseases of 

 Tropical Climates.) Similar observations were made at Newfoundland, and are 

 quoted by Professor Rudolphi. ( Grundriss der Physiologic, 182.) 



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