on the Irritability of Nerves. 1 1 
Exper. 1 . The cutaneus interims nerve of the fore leg of a 
young rabbit was laid bare, where it passes down before the 
biceps flexor cubiti muscle : the nerve was disengaged from its 
lateral attachments ; and, while the limb was in a moderately 
extended state, a probe-pointed bistoury was passed behind it, by 
which means it was divided transversely. The two ends immedi- 
ately receded from each other : the upper portion appeared to 
retract more than the other, and the end lay close to the mus- 
cle, in a straight line, while the end of the lower portion was a 
little bent to one side. The space between them, when mea- 
sured by a pair of compasses, was found to be of an inch. 
The branch of the musculo-cutaneus nerve, which lies near 
to the cutaneus interims, was divided in the same manner ; and 
the retraction of the cut ends was found to have been to the 
same extent. 
In this experiment, the limb was extended, although by no 
means to its utmost limits ; it therefore became a question, whe- 
ther the same degree of retraction would take place in the bent 
state of the limb. 
To determine this point, the experiment was repeated, after 
an interval of four days, upon the other fore leg of the same 
rabbit, with the limb in the bent state : the retraction, how- 
ever, was found to have been exactly to the extent of of 
an inch. 
From this experiment, made under these different circum- 
stances, a retraction of the cut ends of a divided nerve was as- 
certained to take place, which led to the further prosecution of 
the inquiry. 
For this purpose, the phrenic nerve in the horse was selected, 
as being more favourable, in many respects, than most others 
C 2 
