88 
BRITISH ASSOCIATION.— 1835. 
viation from the natural state of the interior surfaces of the heart 
or arteries. 
The second part of the paper developed Dr. Corrigan’s views. 
His theory is, that the sound depends on the simultaneous presence 
of these two conditions, viz. 1st, a current-like motion of the blood 
(instead of its natural equable movement), tending to produce cor¬ 
responding vibrations on the sides of the cavities or arteries through 
which it is moving; and, 2ndly, a state of the arteries or cavities 
themselves by which, instead of being kept in a state of tense ap¬ 
proximation on their contained inelastic blood (which would neces¬ 
sarily prevent any vibration of their sides), they become free to vi¬ 
brate to the play of the currents within on their parietes; and by 
those vibrations cause, on the sense of touch, “ fremissement,” and 
on the sense of hearing, “ bruit de souffiet .” It was shown that these 
two conditions are present in the parietes of the ventricle, and the 
currents of blood striking against them in cases of narrowed auri- 
culo-ventricular openings; in the enlarged and tortuous arteries of 
the placental portion of the uterus permitted by their very free ana¬ 
stomosis with veins and sinuses, and other causes, to become par¬ 
tially flaccid in the intervals of the heart’s contractions, and the ir¬ 
regular currents necessarily assumed by the blood in rushing along 
these comparatively flaccid tubes at their next diastole; and that si¬ 
milar conditions exist in the analogous state of the vessels in aneu- 
rismal dilatations of tortuous arteries. The presence of the two 
conditions was also applied to explain the mechanism of the sound 
in permanent patency of the mouth of the aorta, in the large arteries 
of animals dying of haemorrhage, and in various other instances. In 
conclusion, two experiments were detailed, in which, in one instance, 
a small bladder, and in the other a portion of the gut of an animal, 
was interposed between two cocks, the upper or nearer being the 
cock of a water-cistern, and the lower or further constituting the 
discharging orifice of the bladder or gut, and water then allowed to 
flow through from the cistern. The sound “ bruit de souffiet ,” and 
the sensation “ fremissement,” were perceptible in the intervening 
bladder or gut, until (from the upper pipe pouring in fluid faster 
than the lower discharged it) the bladder or gut became tense, and 
then both sensations ceased, the passage of the fluid through, ne¬ 
vertheless, continuing all the time. The experiment with the blad¬ 
der was applied to explain the occasional presence and absence of 
“ bruit de souffiet ” in aneurisms, the sound being present in an aneu¬ 
rism when, from any circumstance connected with it, its parietes can 
become at all flaccid in the intervals of the heart’s contractions,—- 
not being heard if the parietes remain tensely applied to their con¬ 
tained fluid. 
Dr. Corrigan has in some experiments substituted a gum-elastic 
tube for the portion of gut. 
Dr. Alison read a notice of a few experiments and observations 
which he had made, with the assistance of different friends, on two 
