ON THE PHYSIOLOGY OF THE LUNGS AND AIR-TUBES. 419 
to prevent the blood from coagulating. The aorta was then gal- 
vanised, and the column immediately rose gradually two inches. 
On removing the wires, it still rose a few seconds, and then sunk 
progressively, After it had sunk two inches, the galvanism again 
raised it two tenths, but no more. This was about twenty-five 
minutes after death. The auricles continued to be excitable by 
galvanism more than half an hour after death, the contraction of 
one auricle being followed by that of the other. In this and 
another donkey, I had proved that the arteries contracted during 
life on the application of the galvanic, as well as of ¢hemical and 
mechanical stimuli. 
24. Some tincture of Lobelia eflata, much concentrated by 
evaporation, was injected into the jugular vein of a dog. There 
were symptoms of uneasiness for a few minutes, but no further 
effect. A fluid extract obtained by evaporating Ziss. solution 
of bimeconate of morphia (Squire) was then injected. In twelve 
seconds, peculiar convulsive starts and some general tremor, 
with laborious breathing, followed by death in about a minute and. 
ahalf. Heart was beating when the chest wasopened. Single 
lobes of the lungs being galvanised raised the dynameter co- 
lumn slightly, not more than a tenth. On cutting the lung, the 
sections contracted more distinctly, but much less so than in 
other cases. Trachea expanded. 
25. About half a drachm of extract of conium mixed with 
water was injected into the external jugular vein of a dog. In 
twelve seconds the breathing became very quick and laborious, 
and in a minute the animal was dead. Bronchi not contractile as 
tested by the dynameter, and less than usual on galvanising cut 
portions. The trachea was already contracted so much that 
the ends of the cartilaginous rings were in contact. The heart 
was still irritable. 
I trust that many of the results of the preceding experiments 
are sufficiently evident without further comment. 
Almost all of them prove that the air-tubes are endowed with 
irritable contractility, excitable by electric, chemical, and me-: 
2 aa stimuli, and they possess also tonic contractility (10, 
25). 
The contractility is manifest in all portions of the air-tubes 
(3, 6, 7, 12, &c.). In the trachea and larger bronchi it is anta- 
gonised by the elasticity of the cartilaginous rings (12, 14). 
It does not appear to exist in the vesicular terminations of the 
air-tubes (3). 
This contractility resembles that of the intestines or arteries 
more than that of voluntary muscles, the oesophagus, or heart, 
the contractions and relaxations being more gradual than those 
2E2 
