584 Sir E. Home on the influence of the Nerves 
great violence ; this circumstance induced me to feel the pulse 
at the wrist, and to keep my finger upon it during the time this 
effect upon the pus continued, which was several minutes, cor- 
responding with the pulse at the wrist, which, however, had 
been in no degree disturbed. 
The increased action of the arteries, rendered evident by the 
effect upon the pus, following so closely upon an irritation on 
the neighbouring nerves, made it clear that it arose from that 
cause, and brought to my recollection an instance, in which 
the aorta had been seen pulsating with great violence, in 
consequence of an irritation upon the nerves of the urinary 
bladder. 
To ascertain whether such a connection between the actions 
of nerves and arteries could be demonstrated in a state of 
health, as well as disease,! instituted the following experiments, 
which were made in the presence of Mr. Brodie and other 
gentlemen competent to form a judgment respecting them. 
The carotid artery of a dog was laid bare, the intercostal 
nerve and par vagum, which form one bundle, were separated 
from it by a flattened probe for one-tenth of an inch in length, 
the head and neck were then placed in an easy position, and 
the pulsations attended to by all present, for two minutes, that 
the eye might be accustomed to them in their natural state : 
the nerve passing over the probe was then slightly touched 
with the kali purum. In a minute and a half the pulsations of the 
exposed artery became more distinct; in two minutes the beats 
were stronger, and in three more violent; in four minutes the 
violence was lessened, and in five minutes the action was re- 
stored to its natural state. 
This experiment w'as repeated with the same results upon 
