ON THE PHYSIOLOGY OF THE LUNGS AND AIR-TUBES. 415 
head and dividing the vessels of the neck. The bronchi were 
full of frothy mucus, and on touching any of them with the 
galvanic wires, this froth was exuded from them. Their mea- 
sured size also shrunk under the same influence. 
9. The same results were obtained with the lungs of a calf, 
half an hour after death (by bleeding and pithing). A small 
lobe of the lung when galvanised raised the dynameter three 
tenths. 
10. Two years ago I observed in the lungs of a horse just 
killed by knacking, that the divided ends of the bronchi slowly 
contracted on being irritated with a scalpel; but as no mea- 
surement was used, and as those which were not thus irritated 
also contracted, only more slowly, I did not then consider the 
result conclusive. It may, however, now be arranged among 
other facts of the same kind. 
11. In many instances which I need not now detail, I tried 
to excite the contraction of the air-tubes by chemical irritants, 
such as salt and diluted ammonia. I succeeded with the divided 
ends of the tubes ; but with the dynameter it was more difficult, 
from the difficulty of introducing the irritant without mechani- 
cally affecting the column, and also from the irritant causing 
the formation of mucous viscid froth, which obstructed the 
tubes. The following was the most successful of these at- 
tempts. 
12. A dog was pithed and the lungs exposed by breaking 
back the ribs. To the trachea was tied a tube with two 
branches furnished with stop-cocks. One branch communicated 
with the dynameter; through the other the lungs were to be in- 
flated to give the tubes their full diameter. The irritating fluid 
was poured into the tube of the dynameter in quantity sufficient 
that some might drop into. the trachea on blowing into the 
upper end of the tube. The lungs being moderately inflated, 
the stop-cock of the dynameter was turned, when the column 
rose three inches. The column was then depressed by blowing 
with the mouth till some dropped into the windpipe. On with- 
drawing the mouth the column was driven up three tenths above 
its former level, and slowly rose two tenths more. This rise 
could only be ascribed to the contraction of the tubes excited 
by the irritating liquid in them. By changing the position of 
the lung, several sudden starts of one or two tenths repeatedly 
occurred, probably caused by the irritating fluid coming in con- 
tact with more tubes. But all these movements were much im- 
peded by the viscid froth which collected in the bronchi. The 
lungs being suffered to collapse, the column sank to a level. 
After a while it sunk further two inches below the level; being 
