148 SANGUIFICATION. L.ECT. VII. 



from these results we learn that a turtle-dove weighing 

 187 grammes, and respiring freely at the temperature of 

 + 8^ to 10 centig. [= 46-5 Fahr. to 50] can, by con- 

 suming in 24 hours 5*1 grammes of carbon, and 0*07 

 grammes of hydrogen, develop all the heat required to 

 maintain the body at the temperature of -f- 41 to 42 

 centig. [= 105-8 Fahr. to 107-6,] and at the same time 

 exhale about 3 grammes of aqueous vapour from the lungs 

 and skin. 



Animal Heat. It is,, then, indisputable that an animal 

 is an actual apparatus of combustion, in which carbon is 

 constantly burnt, and from which carbonic acid is always 

 escaping. Such a calorific apparatus has been so consti- 

 tuted as to have, in comparison with the temperature of the 

 surrounding air, a constant, or but a slightly variable, ex- 

 cess of caloric. This excess varies, according to the 

 rapidity of the combustion in this animal calorific appara- 

 tus, and according to the constant temperature of the sur- 

 rounding medium in which it lives. 1 gramme of iron, 

 which oxydizes in the air, and 1 gramme of iron, which 

 oxydizes in oxygen gas, develop each the same amount of 

 heat ; but the latter oxydizes in a second, perhaps, whilst 

 the other takes several hours to perform the same process. 

 Hence, the temperature possessed by the one is vastly greater 

 than that of the other. A mass of grape husks, laid in a 

 heap, undergoes fermentations and becomes very hot ; but 

 the same quantity, arranged in a thin layer, evolves an 

 equal amount of heat, but which is not perceptible, in con- 

 sequence of being too much dispersed. In this way, we 

 can understand the difference of temperature between warm 

 and cold-blooded animals. We cannot have any doubt as 

 to the source of animal heat. It is found in the chemical 

 re-actions of respiration effected in the capillaries, in the 



