MINUTE ORGANISMS TO INFLAMMATION 405 
This conclusion is confirmed by the fact that it is in harmony with and 
elucidates the mode of operation of the most frequent cause of inflammatory 
attacks—exposure to cold. How does a chill of the surface lead to an internal 
organ becoming inflamed ? Why should a draught of cold air upon the chest 
lead to an attack of inflammation of the lungs? First, it seems clear that in 
some way or other the effect is brought about through the nervous system ; for 
the integument only is chilled, and the deeply seated internal organ suffers, 
while the same law of sympathy or nervous connexion which we have seen in 
counter-irritation applies equally here; it is the cooling of the skin nearest 
the internal organ that is most likely to cause its inflammation. And further, 
the cold sometimes ‘strikes in’ with a suddenness that conveys the idea of 
a nervous shock, and seems to preclude the hypothesis of any other agency 
than that of the nervous system. Next we have to ask what immediate effect 
does cold produce upon the nerves of the surface on which it acts? One effect 
which cold certainly does produce is to lower the activity of the nerves on which 
it operates. In this respect it is the converse of heat. It therefore seems 
natural to suppose that cold acts in causing inflammation exactly on the con- 
verse principle that heat may act in curing it ; a diminution of the action of the 
nerves of a part of the surface leading to an increased action of the nerves of 
an internal organ in sympathy with that part. And this view of the matter is 
confirmed by familiar experience. Suppose a man is liable to inflammatory 
disorder of the bowels, what is the time when he must be most careful to keep 
his coat buttoned up when he walks out into the cold air? It is immediately 
after taking a hearty dinner ; it is just at the time when there is the greatest 
amount of physiological activity of the organs liable to inflammation. When 
the nerves of the internal organ are already doing their utmost consistently 
with health, then it is that it is most likely to suffer from additional nervous 
action thrown upon it in consequence of depression of nervous activity in the 
chilled integument with which it sympathizes—exactly the contrary effect, as 
it appears to me, to that of the actual cautery, the mustard poultice, or the 
hot fomentation. 
Let me now give a single example of the influence of the nervous system 
in producing or maintaining chronic inflammation. Suppose a patient comes 
to us with chronic inflammation of the synovial bursa situated over the patella 
and its ligament—chronic housemaid’s knee. This, as we all know, is a very 
obstinate complaint, and may have resisted perfect rest, blistering, and a variety 
of other treatment. If it has existed any length of time, we find that there is 
not only effusion of fluid into the synovial sac, but inflammatory thickening 
of the surrounding tissues. Now, I find that if we make a puncture in the sac 
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