434 FRAGMENTS OF SCIENCE. 



work of reduction, or generate chemical tensions, it 

 is, he contends, incredible that these tensions should 

 be caused by the mystic play of the vital force. Such 

 an hypothesis would cut off all investigation; it would 

 land us in a chaos of unbridled phantasy. ( I count/ 

 he says, ' therefore, upon your agreement with me 

 when I state, as an axiomatic truth, that during vital 

 processes the conversion only, and never the creation 

 of matter or force occurs/ 



Having cleared his way through the vegetable 

 world, as he had previously done through inorganic 

 nature, Mayer passes on to the other organic kingdom. 

 The physical forces collected by plants become the 

 property of animals. Animals consume vegetables, and 

 cause them to reunite with the atmospheric oxygen. 

 Animal heat is thus produced; and not only animal 

 heat, but animal motion. There is no indistinctness 

 about Mayer here; he grasps his subject in all its de- 

 tails, and reduces to figures the concomitants of mus- 

 cular action. A bowler who imparts to an 8-lb. ball a 

 velocity of 30 feet, consumes in the act ^ of a grain 

 of carbon. A man weighing 150 Ibs., who lifts his 

 own body to a height of 8 feet, consumes in the act 1 

 grain of carbon. In climbing a mountain 10,000 feet 

 high, the consumption of the same man would be 2 oz. 

 4 drs. 50 grs. of carbon. Boussingault had determined 

 experimentally the addition to be made to the food of 

 horses when actively working, and Liebig had deter- 

 mined the addition to be made to the food of men. 

 Employing the mechanical equivalent of heat, which 

 he had previously calculated, Mayer proves the addi- 

 tional food to be amply sufficient to cover the increased 

 oxidation. 



But he does not content himself with showing, in a 

 general way, that the human body burns according to 



