248 
PROFESSOR MATTE UCCl’S ELECTRO-PHYSIOLOGICAL RESEARCHES. 
Postscript. 
Received May 20th, 1847. 
Extract from a Letter from Professor Matteucci to Mr. Bowman , dated Pisa. 
( Translation .) 
“ As I do not propose to resume my electro-physiological researches, at least for 
some time to come, I should feel obliged by your adding the following fact, which is 
a very striking one, to the memoirs just presented to the Royal Society. 
“You know the law of the electro-physiological action of the current on mixed 
nerves : you know that this law is very different in the case of the simple nerves of 
the anterior roots, as I found in conjunction with Longet. 
“Now, if you render a rabbit or a dog insensible by the inspiration of sulphuric 
ether, and, while in that state, pass the direct current along one sciatic nerve, and 
the inverse along the other, you will have the following phenomena: — 
“ 1st. If the animal is not totally insensible, some cries of pain at the commence- 
ment of the direct current, which continue more or less while it is passing, but no 
contraction : the contraction with this current only appears on interrupting the cur- 
rent. 
“ 2nd. With the inverse current, no cry or sign of pain on completing the circuit, 
if the animal is thoroughly etherized, and slight cries if not quite etherized : con- 
traction of the muscles in closing, none on opening the circuit. 
“ These are the phenomena of the anterior roots. 
“3rd. Now cut the nerves at their insertion into the spinal marrow: instantly the 
phenomena are reversed, and we have the ordinary play of the mixed nerves ; that is 
to say, the contraction with the direct current takes place on closing, and that with 
the inverse current on opening the circuit. 
“ In the mixed nerves, therefore, the phenomena are complicated by the presence 
of the sensitive fibres. 
“This conclusion appears to me very important, and I much regret that I am un- 
able to tell you that the same things occur with the frog. Etherized frogs give the 
ordinary phenomena of mixed nerves, as heretofore. 
“ But who knows how the two kinds of fibres mingle in the nerves of different 
animals? Who is so ignorant as to believe that, in such matters, he can know all, 
and all at once ?” 
