ON THE NERVES IN GENERAL. 



extreme tenuity conceals them from the eye: what may in- 

 duce us to admit this, is the sensibility which these tissues 

 present in diseases. It is true that the hypothesis according 

 to which the nerves act by means of an imponderable fluid, 

 susceptible of extending its influence beyond their apparent 

 termination, may explain, to a certain point, this phenome- 

 non. According to this hypothesis, nervous action Is trans- 

 mitted beyond the nerves, and across the organic substance, 

 as nutrition takes place beyond the termination of the arteries, 

 by a sort of imbibition. 



It is worthy of remark, that in some circumstances where 

 there exist paralysis of sensation, and not of motion, the in- 

 flammations which develope themselves are not accompanied 

 with pain 5 which would lead to the opinion that these same 

 cords are the seat of general sensation and of painful sensa- 

 tion, peculiar to inflammation, and that it is not solely the 

 nerves of the blood vessels which cause this last to be expe- 

 rienced. 



778. The parts in which the peripheric extremities of the 

 nerves terminate in the most evident manner, are then the 

 tegumentary membranes and the senses which form a part of 

 them, the muscles and the arteries. 



The senses* are organs more or less complicated, by means 

 of which external bodies are perceived; they have a structure 

 calculated to receive an impression; they are connected with 

 the nervous centre by nerves very much developed: these 

 organs are those of tact or touch, of taste, of smelling, of hear- 

 ing and of seeing. 



The muscles are connected with the nervous centre by nu- 

 merous and greatly ramified nerves (662). The arteries re- 

 ceive a great number of nerves; but they are not all distributed 

 in the same manner: 1st, some only accompany them and sur- 

 round them as the ivy surrounds trees, without penetrating 

 into their tissue, unless perhaps after having accompanied 

 them for a greater or less distance: such are those which ac- 

 company the vertebral arteries, the internal carotids and the 



* See Blainville, JPrincipes d'Jlnal. comparer, t. i. Paris, 1822. 



