244 ANIMAL HEAT. 



temperature is kept down in a heated atmosphere by the dimi- 

 nution of chemical changes in the lungs, and by free secretion 

 and evaporation from the bronchiae and skin. How much each 

 contributes is not ascertained ; but the importance of evaporation 

 was shown in some experiments of Dr. De la Roche, who raised 

 the temperature of animals considerably by placing them in a 

 heated atmosphere loaded with moisture; thus preventing evapor- 

 ation. In a cold atmosphere, the chemical changes in the lungs 

 are great, and the skin is dry : the aqueous matter which leaves 

 the body then, does so chiefly by the kidneys, in a fluid form ; and 

 its amount is much less ; because our thirst, and the amount of 

 our drink, are much less. 



Dr. Philip has made experiments equally conclusive with those 

 of Dr. Le Gallois against the inferences drawn by Sir B. Brodie. 

 As very little air is taken into the lungs in natural inspiration, 

 and a regard to the bulk and frequency of each inspiration not 

 always attended to in experiments, it is very probable that this 

 gentleman had thrown too much air into the lungs ; so that the 

 unnatural quantity of cold air, and the augmented secretion of 

 bronchial fluid, made the temperature fall. By impelling little, 

 and that not frequently, Dr. Philip found that artificial respir- 

 ation, after the destruction of the brain, actually retarded the 

 cooling of the animal, while stronger respiration did actually 

 cool the body. 



Of two rabbits killed in this way, their temperature being 104-, 

 one was subjected to 6 artificial inspirations, and the other to 

 from 26 to 30, in a minute ; the temperature of the former was 

 100 at the end of an hour, and the latter 98. Of two, with the 

 temperature of 102'5, one was undisturbed, and one subjected to 

 about 30 inspirations in a minute : the temperature of the former 

 at the end of half an hour was 98*75 ; of the latter, only 98'5. 

 But, the lungs of the latter being now inflated only about twelve 

 times in a minute, the temperature of the former at the end of 

 another half hour was 95-25, and of the latter, 96. In one expe- 

 riment in which the lungs were inflated but a few times in a 

 minute, the temperature actually rose nearly a degree by arti- 

 ficial respiration.* Dr. Hastings, at the same time, made similar 

 comparative experiments, and with similar results. In one, the 



a An Experimental Inquiry into the Laws of the Vital Functions, 3d edit, 

 p. 180. sqq. 



