730 
N. R. MACAULAY. 
that we have the second stage, appearing about the second or 
third day. When this stage occurs, percussion and ausculta¬ 
tion give definite results, and we are able to say how much of 
the lung is affected. In this stage the temperature generally 
ranges from 103° to 106°, and remains about the same until 
from the seventh to tenth day when, if the animal is to recover 
it gradually falls, the appetite improves and congested condi- 
tionof lung gradually disappears. If the case is to terminate 
seriously we find no diminution of temperature and an in¬ 
crease in size of part over the lung where there is no res¬ 
onance or percussion, and this is shortly followed by death. 
Remembering the conditions of the lung in pneumonia, 
with all the incidental changes accompanying the inflamma¬ 
tion, let us look upon the action of a smart counter-irritant, 
say a mustard blister, as that is perhaps most frequently ap¬ 
plied, and see in what way it will help toward recovery. 
When first a blister is applied to the skin there is a pleas¬ 
urable sensation of warmth, which is quickly followed by a 
tingling, burning and then intense pain. We can some of us 
speak very feelingly on this point, knowing from personal ex¬ 
perience how a blister acts.. 
When a blister is applied to the skin its first action on the 
nerves causes a momentary constriction of the blood vessels, 
followed quickly, however, by an enlargement of the vessels 
by distention of their caliber and a consequent congestion 
with blood. 
Up to this point, in comparing the actions of the blister 
and the cold on the system, are they not almost identical ? 
The main difference in the results appears to be that one — 
the cold—has been more general and the other merely local 
in its effects. The stimulus to the nerves has been as differ¬ 
ent almost, as it is possible for them to be, but in each case 
their action on the nervous system must have been alike as 
far as the vaso-motor centre is concerned, because we find the 
same chain of phenomena following each of the irritants. 
Another point, however, in the action of the blister on the 
nervous system has yet to be considered, and that is the sen¬ 
sation of pain it causes. What effect has this on the internal 
