190 REPORT—1840. 
undulation downwards during auricular systole evinced by a 
diastole followed by a systole, both very slight, nothing decided 
was observed. As in all former observations the ventricles 
and auricles respectively acted together. 
OBSERVATION XII. 
The second and older animal was prepared by injection of 
woorara, and, after establishment of artificial breathing, the 
left ribs were cut quite close to the mesial plane, so as to 
expose fully the apex in every motion. 
(Note.—The former was opened in the same way and with 
the same effect.) The pericardium was then opened, and the 
following results were obtained. 
S. 1. The hard substance (sole leather) weighted with lead, 
was applied to the heart, and the same result as in the former 
experiment obtained, viz., a sudden abrupt elevation or jerk 
upwards of the lead was obtained, and a stroke against the 
stethoscope heard distinctly at several yards, and the range of 
oscillation or motion of the lead was about half an inch. 
S. 2. On opening the pericardium the auricles and ven- 
tricles were acting as in the former observation, viz., the 
auricles first after the rest or pause, and the ventricles imme- 
diately after the auricles. No auricular sound was detectible ; 
no distinct second sound heard. Heart acting hurriedly and 
with varying quickness, but always above the healthy standard. 
S. 3. The motions of the ventricle very conspicuous, and as 
in last observation, viz., striking diminution of horizontal 
transverse and of longitudinal diameters, and increase of trans- 
verse vertical diameter in systole, and in diastole increase of 
the two former diameters, and decrease of the last. And in sy- 
stole the apex was raised, as was the whole body of heart, by 
an elevation of the central longitudinal axis, which was effected 
partly by the assumption of a globular form in the previously 
compressed central inferior surface, and partly by the visible 
protrusion of the previously depressed central superior surface 
of the ventricles. 
So long as this observation lasted both auricles seemed to 
act with equal pertinacity ; the right auricle being however 
snipped, and long after the ventricles had ceased, the blood 
gushed out of the right auricle only when the auricle con- 
tracted, and the hemorrhage ceased nearly during the diastole 
of the auricles. 
S. 5. No other appearances observed in the veins than in 
the former experiment, viz., a slight diastole with the auricu- 
lar systole followed by a systole with auricular diastole. 
