IX.] THE DYNAMICS OP LIFE. 101 



bution of heat in the body ; but we have evidence that the 

 temperature of the whole body may be lowered by injury to 

 the nervous system. It has been observed by Sir Benjamin 

 Brodie, and by others who have repeated his experiments, Effect of 

 that when the spinal cord of a rabbit or other animal is ^^g ^mal 

 divided in the neck, and the action of the lungs (which cord, 

 otherwise would cease in consequence of the paralysis of 

 the nerves that supply their muscles) continued artificially, 

 so as to produce the normal quantity of carbonic acid, the 

 temperature of the body falls. Now, we know that a 

 definite quantity of actual energy is due to the formation 

 of a definite quantity of carbonic acid by oxidation, 

 whether in the living organism or in a furnace : in the ex- 

 periment in question this energy does not appear as heat ; 

 what then becomes of it ? I believe it is transformed into 

 vital energy. I think the only possible interpretation of this 

 experiment is, that the energy which becomes actual in 

 the formation of carbonic acid by oxidation in the body, is 

 in part transformed, not at once into heat but into vital 

 energy, which the nervous system is capable of afterwards 

 transforming into heat. Consequently, when the nervous 

 system is in great part paralysed by cutting the spinal 

 cord, the production of vital energy, which is a function of 

 the whole organism, goes on as before ; but its transforma- 

 tion into heat, which is a function specially of the nervous 

 system, is hindered. 



I admit, however, that it is not generally a satisfactory 

 mode of reasoning, to say that a particvdar solution must 

 be true because it is the only possible one. We demand, 

 and reasonably demand, more direct proof. In this case 

 there is another experiment, which is the exact correlative 

 of Sir Benjamin Brodie's, and shows us what has become Experi- 

 of the energy in question. Brown- S^quard weighted the mental 

 hind legs of living frogs, and thus ascertained what weight that the 

 they were capable of raising when the muscles of the legs ^^^^ ®* 

 were excited to contract by pinching the toes : this weight energy, 

 was taken as the measure of the contractile force of the 

 muscles. He then divided the spinal cords of the frogs, 

 and found that twenty-four hours after the operation the 



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