]38 ON ANIMAL SECRETIONS. 



abounds with immediately applicable to the present inquiry, yet it fur- 

 niflhes two important facts, one, that a Voltaic battery can 

 be formed in a living animal, the other, that nerves are es- 

 sentially necessary for its management; for in these fish the 

 nerves connected with the electrical organs exceed those 

 that go to all other parts of the fish, in the proportion of 

 twenty to one. The nerves are made up of an infinite 

 number of small fibres, a structure so different from that 

 of the electric organ, that they are evidently not fitted to 

 form a Voltaic battery of high power; but their structure 

 appears to Mr. Davy, to adapt them to receive and preserve 

 a small electrical power. 

 Nerves and That the nerves arranged with muscles, so as to form a 



muscles form Voltaic battery, have a power of accumulating and cornmu- 

 «uc a atter). u j catm g electricity, is proved by the well known experiment 

 of taking the two hind legs ef a vivacious frog, immedi- 

 ately after they are cut off; laying bare the crural nerves; 

 applying one of these to the exposed muscles of the other 

 limb; and then, when the circle is completed by raising the 

 other crural nerve with a glass rod, and touching the mus- 

 cle of the limb to which it does not belong, the muscles of 

 both are excited to contractions. 

 Circumstances There are several circumstances in the structure of the 

 in the structure nerves, and their arrangements in animal bodies, which do 

 not applicable not a PP tar at a " applicable to the purposes of common sen r 

 *o sensation, sation, and the uses of which have not even been devised. 

 Among these are the plexuses in the branches of the par 

 vagum wind) go to the lungs, and in the nerves which go 

 to the limbs; the ganglions, which connect the nerves be- 

 longing to the viscera with those that supply the voluntary 

 muscles; and the course of the nerves of the viscera, which 

 keep up a connexion among themselves in so many dif- 

 ferent ways. 

 Bloodvessels The organs of secretion are principally made up of 

 ofthe secretory arteries and veins; but there is nothing in the different 



organs do not i • , • •> i •«. ' i • 



account for modes in winch tnese vessels ramify, that can in any way 



ti.cir actions, account for the changes in the blood, out of which the 



* secretions arise. These organs are also abundantly supplied 



with nerves. 



Experiment* With a view to determine how far any changes could be 



produce4 



