292 
PROFESSOR MATTEUCCl’S ELECTRO-PHYSIOLOGICAL RESEARCHES. 
I took the frogs as they came to hand, from among a considerable number, and 
divided the spinal marrow at about the middle. Twelve hours after this operation 1 
began an experiment, preparing at the same time the frogs whose spinal marrow had 
been divided, and others which were intact. 
In order that the comparison should be as perfect as possible, I employed succes- 
sively in Breguet’s apparatus for measuring contractions, two frogs, one of which 
had the spine divided, the other entire. In each experiment I operated on four frogs 
in the former, and four in the latter state. I made my experiments with a direct 
current, keeping the circuit closed as short a time as possible, and marking the va- 
riations of the needle of the dynamometer after ten or twelve passages of the current, 
because it is then only that the variations become constant ; if the passage of the 
current in the same frog is prolonged, the variations gradually diminish ; operating 
with a certain degree of dexterity, experiments on eight frogs may be completed in 
less than a quarter of an hour. 
The following are the results of two experiments : — 
Exp. 1. 
Contraction of a frog the spinal marrow of which Contraction of a frog with the spinal marrow 
had been divided 12 hours. entire. 
o o o 
16 to 14 
14 
18 20 
18 
18 16 
12 
20 
12 
20 
12 
After 18 hours. 
O O 
Exp. 2. 
o 
24 to 22 
8 
22 24 
10 
22 16 
12 
17 16 
12 
According to these results, and others of the same kind, which it is unnecessary to 
give here, it is clearly proved by experiment that the contraction excited in the muscles 
of a frog, of which the spinal marrow has been divided from twelve to eighteen hours, 
is stronger than that which is obtained under the same circumstances from the mus- 
cle of a frog immediately after it is killed, without having been previously subjected 
to any alteration in its nervous system. 
An observation which I had occasion to make in all my experiments, gave me 
some insight into the cause of this singular phenomenon. If a vigorous frog is 
rapidly prepared and subjected to experiment in the dynamometer, the first con- 
