Itoyal Socic/y. 531 ■ 



these parts being, in man, almost wholly confined to the brain ; while 

 in some animals they extend also to a considerable portion of the 

 spinal cord. The functions of the sensorial powers are those strictly 

 termed mental, of which sensation and volition are the simplest, and 

 the onlv powers of this class which are concerned in the maintenance 

 of life. ' 



The functions of the living blood are evidently those of supplying 

 the proper materials, in their requisite condition, (to the preservation 

 of which the vital powers are essentialj) for the action of the nervous 

 power, properly so called, in the processes of secretion and assimila- 

 tion. The seat of the powers of the blood is in itself; as ai)pears 

 from its retaining them for a short time after it is separated from the 

 body. 



These four vital powers, viz. the muscular, the nervous, the sen- 

 sorial, and that of living blood, have no direct dependence on one 

 another ; for each can, for however short a time, exist independently 

 of the others : but each has an indirect dependence, more or less re- 

 mote, on all the other three for the maintenance of their organs. 



The author then proceeds to inquire into the nature of these se- 

 veral powers. The sensorial and muscular powers, and the powers of 

 the living blood, are manifestly peculiar to the living animal, no ana- 

 ogous powers being perceptible in inanimate nature. But this ex- 

 clusiveness does not belong to the nervous power, for experiment shows 

 us that when the oxygen and carbon of the blood are combined by its 

 influence, a substance results which is identical with that produced in 

 the laboratory of the chemist. An analogy, too strong to be wholly 

 disregarded, exists therefore between its effects and those of the powers 

 which operate in inorganic nature. This consideration, as well as 

 others stated by the author, induced him to make many experiments 

 to determine how far the other functions of the nervous influence bear 

 a similar analogy to the operations of inanimate nature; and, in par- 

 ticular, to inquire whether voltaic electricity, applied under the same 

 circumstances as those under which the nervous influence operates, 

 and applied after the removal of that influence, and ihe consequent 

 cessation of its functions, would produce the same effects. His en- 

 deavours were crowned with complete success ,• all the functions of 

 the nervous power being capable, as far as he and others could judge, 

 of being perfectly performed by voltaic electricity. He states that the 

 results of his experiments on this subject were confirmed by a public 

 repetition of them both in London and in Paris ; as were likewise 

 those of another set of experiments suggested by the following rea- 

 soning. If the nervous influence could be made to pass through any 

 other conductor than the nervous textures to which it belongs in the 

 living animal, we should have a i)roof, independent of all other evi- 

 dence, that this influence is not a vital power, properly so called j 

 because it must be universally admitted that such a jjowcr can exist 

 only in the texture to which it belongs. In this attempt he was for 

 some time baffled ; but at length, overcoming the obstacles which had 

 impeded his eftorts, he succeeded: and, having undergone the same 

 i)ublic ordeal as the former, the results are no longer questioned. 



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