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XXVII. Report made to the Academy of Sciences on a Paper 

 of M. Flourens, entitled ^^Determination of the Properties 

 of the Nervous System, or Physical Researches concerning 

 Irritability and Sensibility." By M. G. Cuvier. 



'X'HE Academy has directed MM. Portal, BerthoUet, Pinel, 

 -■- Dumeril, and myself, to give an account of a paper of 

 M. Flourens, entitled " Detei'mination of the Properties of 

 the Nervous System, or Physical Researches concerning Irri- 

 tability and Sensibility." 



This paper may be considered under three aspects; the ex- 

 periments made by the author, the consequences he derives 

 from those experiments, and the language in which he ex- 

 presses them. He has repeated before us his principal ex- 

 periments, and they appeared to us exact. We have followed 

 his arguments with attention, and the greater number of them 

 seem to us just; but the language he has employed differs in 

 some important points from that generally received, and may 

 give occasion to objections and to misunderstandings, if we do 

 not endeavour at once to rectify it. It is indeed from a desire 

 to be useful to the author, by giving the results of his experi- 

 ments with more cleai'ness, that we shall begin this Report 

 with some criticisms of his nomenclature. 



When a nerve is pinched or pierced, the muscles to which 

 it is distributed contract with more or less force, and at the 

 same time the animal feels pain more or less intense. When 

 a nerve is separated from the rest of the nervous system by a 

 ligature or by section, and it is pinched or pierced in the same 

 manner above the ligature or section, contractions in (he muscle 

 are again produced ; but the animal no longer feels pain ; it 

 loses at the same time the power of commanding those con- 

 tractions of the muscle which that nerve animates. These 

 facts have been known ever since attention has been given to 

 physiological experiments. Herophilus and Erasistratus de- 

 monstrated them ; Galen left them in writing, and it is upon 

 them that this fundamental proposition rests, that the nerves 

 are organs by -which the animal receives sensations and exercises: 

 voluntary motions. 



A more minute attention to the movements which take place 

 in the animal body, has also discovered that it is not by me- 

 chanical contractility that the nerve causes the muscles to con- 

 tracts On the contrary, the nerve, during this action, re- 

 mains perfecdy motionless ; it is not even necessary to employ 

 its intervention. A prick, an immediate irritation upon the 

 muscle, causes it to contract; this effect is visible for some time 

 even upon a muscle of which the nerve has been divided ; — 

 even upon a nmscle detached from the bodv. 



This 



