38 



THE ANIMAL ASA MACHINE. 



14. The Animal as a Prime Motor.* — Hirn was 

 probably the first and the greatest of those who have 

 sought to measure up the energies of Hving creatures, 

 and to follow the transformations which occur in the 

 processes of vital organization and animal exertion. f 



The origin of heat in the bodies of hving animals has 

 been a matter awakening the greatest interest and 

 curiosity from the earliest times. The ancients thought 

 heat and light a part of the vital power, due to the 

 creative act, and without immediate source in the 

 processes of vital existence. They thought the 

 act of breathing a necessary process of cooling and 

 removal of excess of this spontaneously generated 

 heat, due to the fact of life simply. Since the estab- 

 lishment of the principles of energy in modern times, 

 however, the philosopher has only concerned himself 

 as to the method of production of this heat, recogniz- 

 ing the fact that it must have its origin, as must all the 

 exhibitions and expenditures of energy that accompany 

 it in the living being, from the potential and latent 

 energies of combustible substances subjected to the 

 processes of digestion and assimilation in the body. 

 The scientific man of later times sees in the vital pro- 

 cesses a transformation of energies originating in a 

 slow combustion at low temperature, with changes of 

 form of the resulting energies which, though none the 

 less certainly phases of the chain of vital phenomena 

 which he studies, are not all fully understood, or as 

 yet all detected and rendered evident by research. 

 The chemical compositions of these combustibles are 



* From Cassier's Magazine, Feb., 1892; by R. H. Thurston, 

 f La Thermodynamique et I'Etude du Travail chez les Etres vivants. 

 G. A. Hirn, Paris. Bureaux des Revues, 1887. 



