of animal Secretions. 387 
nicating electricity, is proved by the well known experiment 
of taking the two hind legs of a vivaceous frog, immediately 
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 muscle of the limb to 
which it does not belong, the muscles of both are excited to 
contractions. 
There are several circumstances in the structure of the 
nerves, and their arrangements in animal bodies, which do 
not appear at all applicable to the purposes of common sen- 
sation, and whose uses have not even been devised. Among 
these are the plexuses in the branches of the par vagum which 
go to the lungs, and in the nerves which go to the limbs. The 
ganglions, which connect the nerves belonging 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 different ways. 
The organs of secretion are principally made up of arteries 
and veins ; but there is nothing in the different modes in which 
these vessels ramify, that can in any way account for the 
changes in the blood, out of which the secretions arise. These 
organs are also abundantly supplied with nerves. 
With a view to determine how far any changes could be 
produced in the blood by electricity, at all similar to secretion, 
Mr.W. Brande, who has begun his career in animal chemistry 
with so much success, made the following experiments, in the 
suggestion of which Mr. Davy afforded him every assist- 
ance. 
